Next Article in Journal
A Novel SOH Estimation Method for Lithium-Ion Batteries Based on the PSO–GWO–LSSVM Prediction Model with Multi-Dimensional Health Features Extraction
Next Article in Special Issue
Effect of Cassava Flour and Ginger Powder Addition on Physicochemical and Antioxidant Properties of Bread
Previous Article in Journal
PerMSCA-YOLO: A Perceptual Multi-Scale Convolutional Attention Enhanced YOLOv8 Model for Rail Defect Detection
Previous Article in Special Issue
Evaluation of the Effect of the Technical Guidelines for Chilean Milk Dietary Service on the Microbiological and Nutritional Quality of a Powdered Infant Formula
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Applied Sciences
Volume 15
Issue 7
10.3390/app15073590
applsci-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Olfactory Capacity and Obesity: A Narrative Review of the Literature

by
Samuel Durán-Agüero
1 and
Ana María Obregón-Rivas
2,*
1
Escuela de Nutrición y Dietética, Facultad de Ciencias de la Rehabilitación y Calidad de Vida Universidad San Sebastián, Santiago 7510000, Chile
2
Escuela de Nutrición y Dietética, Facultad de Ciencias de la Rehabilitación y Calidad de Vida Universidad San Sebastián, Concepción 8030000, Chile
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(7), 3590; https://doi.org/10.3390/app15073590
Submission received: 27 January 2025 / Revised: 18 March 2025 / Accepted: 21 March 2025 / Published: 25 March 2025
(This article belongs to the Special Issue Food Security, Nutrition, and Public Health)
Browse Figures
Versions Notes

Abstract

:
The sense of smell plays a crucial role in food perception, influencing dietary choices and eating behavior. This narrative review explores the relationship between olfactory function and obesity, addressing the question: how does smell influence the perception, selection, and eating behavior of food? The review highlights that individuals with obesity may experience reduced olfactory sensitivity due to hormonal imbalances, such as elevated leptin and reduced ghrelin levels, which can alter odor perception and lead to unhealthy food preferences. Additionally, those with olfactory dysfunction may compensate by seeking saltier or sweeter foods, increasing the risk of obesity. The review also notes that olfactory responses vary across age groups, with some obese adolescents exhibiting greater olfactory sensitivity. The impact of the COVID-19 pandemic on olfactory function and eating habits is discussed, emphasizing the need for interventions that incorporate sensory aspects of eating to combat obesity. A comprehensive approach involving neuroscience, psychology, and public health is recommended to develop effective and personalized solutions for obesity prevention and treatment.

1. Introduction

Obesity, characterized by the excessive accumulation of body fat, is a multifaceted issue and a major public health concern worldwide [1,2]. It is also a significant risk factor for non-communicable chronic diseases, such as cardiovascular diseases, type 2 diabetes, fatty liver disease, and certain types of cancer [3]. According to the World Health Organization (WHO), in 2016, 1.9 billion adults were classified as overweight, of which 650 million were obese [4].
The causes of obesity are diverse. Key factors include not only insufficient daily physical activity but also the excessive consumption of low-cost, highly palatable, energy-dense, nutrient-poor foods and beverages with high sugar content. For instance, in 2018, the global consumption of sugary beverages was estimated to be 248 g per week [5]. Additionally, the overall quality of diets worldwide remains modest [6].

Smell and Diet

The etiology of obesity is multifactorial, involving both extrinsic and intrinsic factors. Among the extrinsic factors is the modern food environment, which promotes the excessive consumption of high-calorie foods, particularly ultra-processed products. These foods are rich in calories, sugar, saturated fats, trans fats, and sodium and are generally characterized by intense aromas [7]. Among the chemosensory organs, it has been demonstrated that the sense of taste plays a significant role in nutrient selection and dietary intake [8].
This dynamic balance between food consumption and energy expenditure requires a coordinated integration of inputs from the peripheral sensory system with internal response systems. In this context, the sensory system guides animals toward food, shapes food preferences, and contributes to the experience of satiety after consumption, thereby promoting dietary learning [9].
The sense of smell plays a key role in our ability to enjoy food, as olfactory signals and odor perception significantly contribute to the experience of flavor, food preference, acceptability, and intake. Additionally, food odors released in the oral cavity travel to the olfactory receptors located in the nose, significantly stimulating salivation, insulin release, and gastric acid secretion in the stomach [10]. Furthermore, food odors act as triggers for food consumption in animals [11].
Studies have shown that individuals with a reduced sense of smell are less attracted to new foods and derive less pleasure from eating [12]. Additionally, there is evidence of an association between poor diet quality and a lower variation in dietary habits among patients with olfactory dysfunction [13].
The sense of smell is a sensory system present in animals, including humans. Odorant receptors expressed in olfactory sensory neurons can detect and distinguish a wide variety of olfactory signals [14]. The sensitive and precise detection of food can guide animals toward a nutrient source, stimulating appetite responses. Additionally, chemosensory perception is a key determinant of food palatability and is believed to play a fundamental role in food choices and energy intake [15,16,17].
In this context, it has been observed that the smell of food can elicit either an attractive or aversive response mediated by odorant receptors [14].
The sense of smell goes beyond mere sensory perception and is closely linked to hypothalamic function. This connection is evident in findings that show olfactory acuity decreases in a state of satiety but increases in a state of hunger [18,19,20]. In other words, hunger enhances olfactory sensitivity, while satiety reduces it, indicating a reciprocal relationship between food intake and olfactory sensitivity. The purpose of this narrative review is to answer the following research question: how does smell influence the perception, selection, and eating behavior of food? An overview of the role of smell in food perception and selection as well as its influences on eating behavior and obesity is presented in this narrative review.

2. Materials and Methods

For this study, the PubMed, Scopus, Web of Science and SciELO databases were used. There were no time restrictions on the search, and the languages used were English and Spanish. The study included research conducted on both animal and human models. Articles that included cancer and neurodegenerative diseases were excluded. The following keywords were used to search the databases: olfactory function OR smell OR odor OR odour OR olfactory OR hyposmia AND obesity OR extra weight OR weight OR metabolic disease OR metabolic function OR nutritional status (smell OR odor OR odour OR olfactory OR hyposmia) AND (obesity OR “extra weight” OR weight OR “metabolic disease” OR “metabolic function” OR “nutritional status”). The process is summarized in Figure 1.

3. Results

3.1. Smell and Energy Regulation

The hypothalamus is a master regulator of whole-body energy homeostasis [21]. It can detect an individual’s nutritional state and integrate this information to regulate food intake, glucose levels, and energy balance [22]. In this context, food odors perceived by the olfactory system alter the activation state of hypothalamic AgRP and POMC neurons, thereby modulating appetite and satiety circuits [23,24].
Research shows a close relationship between the olfactory system and energy balance. Different odors are sensed by olfactory sensory neurons (OSNs) located within the olfactory epithelium (OE). Bidirectional connections have been observed between the olfactory circuit and hypothalamic nuclei, which maintain the body’s homeostasis. The hypothalamus is organized into anatomically defined neuronal groups, known as nuclei, which form interconnected neural circuits through axonal projections and regulate functions such as energy balance. Among these nuclei is the arcuate nucleus (ARC), which contains two main cell populations: those that express orexigenic neuropeptides, such as agouti-related peptide (AgRP) and neuropeptide Y (NPY), and those that express anorexigenic neuropeptide precursors, such as proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART). The sense of smell influences the metabolic state by participating in the cephalic phase of digestive physiology. Its function is also modulated by molecules related to food intake and by circulating levels of peptides that regulate energy metabolism. Specifically, orexigenic peptides like ghrelin enhance olfactory sensitivity, which is reduced by anorexigenic peptides such as leptin and insulin. In the case of individuals with obesity, peptides related to food intake would act as follows. Individuals with obesity are characterized by high circulating levels of leptin and insulin, which bind to their receptors, which are particularly abundant in olfactory structures. This exerts an inhibitory effect primarily on the mitral cells of the olfactory bulb, the first processing point of olfactory information. These cells play a key role in representing the identity and intensity of odors. In obesity, there is a reduction in circulating ghrelin levels, leading to a consequent decrease in olfactory function due to the diminished effect of this hormone. Previous studies have shown that olfactory dysfunction affects food intake, potentially leading individuals to adopt an unbalanced diet. These individuals report that food is less enjoyable and less flavorful. To compensate for the reduced gratification resulting from diminished olfactory stimulation, they tend to prefer more palatable foods, such as sweet and high-fat items, over fruits and vegetables, and they increase their use of condiments and spices (Figure 2).
A reduced sense of smell is referred to as “anosmia”, with a prevalence of 15%, while approximately 2% of individuals experience a total loss of smell, known as “hyposmia” [25]. It has been suggested that olfactory and gustatory perception can influence food choices and eating behavior, as changes in smell and taste at the individual level may play a crucial role in food preferences, selection, and consumption [26,27].

3.2. Studies on Animals and Insects

Animal studies have shown that olfactory behavior and sensitivity are more active during fasting compared to a state of satiety [28,29]. These changes are associated with an increase in orexigenic molecules (ghrelin, neuropeptide Y, and orexins) during fasting and, conversely, a decrease in anorexigenic molecules (insulin, cholecystokinin, and leptin) [17,30].
On the other hand, after food intake, olfactory sensitivity decreases, a process regulated by satiety signals [31]. Additionally, previous studies have demonstrated that impaired olfactory function correlates with overweight and obesity, suggesting that reduced olfactory function may delay satiety and lead to increased body weight [32]. Research suggests that the olfactory system is closely linked to neural systems that regulate food intake by detecting metabolic states [33]. Moreover, the olfactory bulb contains receptors for various hormones and neuromodulators involved in food intake regulation, including insulin, leptin, ghrelin, orexin, and endocannabinoids [33] (Figure 1). Thus, the sense of smell is potentially modulated in response to changing levels of molecules such as ghrelin, orexins, neuropeptide Y, insulin, leptin, and cholecystokinin [33]. While it is known that these peptides and their receptors modulate the olfactory system, how changes in adiposity influence olfactory function remains unclear.
Changes in taste perception have also been observed across different body mass index (BMI) levels [10,34]. However, it remains unclear how olfactory abilities are related to adiposity (or vice versa) by directly impacting eating behavior [35,36,37]. Currently, much of the knowledge about pro-olfactory neuroanatomical pathways comes from animal models. It is hypothesized that odor-evoked responses originate from first-order neurons in the nasal mucosa, which project to the olfactory bulb (OB). This olfactory information is then transmitted to the anterior olfactory nucleus, piriform cortex, and amygdala, which together are considered the primary olfactory cortex. This complex neural network plays a fundamental role in individual olfactory performance, odor-driven behaviors, and food consumption [17]. To some extent, this gap in knowledge reflects the relative complexity of the mammalian olfactory system [32,38,39].
An animal study showed that mice with conditional ablation of mature olfactory sensory neurons (OSNs) were more resistant to diet-induced obesity and showed increased thermogenesis in brown and inguinal fat. Loss of sense of smell after obesity not only prevented weight gain, but also improved fat mass and insulin resistance. The results suggest that reducing olfactory input activates the sympathetic nervous system, causing lipolysis to occur in adipocytes. In contrast, ablation of the IGF1 receptor in OSNs improved olfactory performance and increased adiposity and insulin resistance. These findings reveal a dual role of the olfactory system in the regulation of energy homeostasis [40].
A study conducted on Drosophila melanogaster flies showed that defects in olfactory sensory neurons reduced food intake, increased triglyceride levels, enhanced resistance to hunger and desiccation, and decreased cold stress. Additionally, the disruption of the neuropeptide F receptor or insulin signaling in olfactory sensory neurons also modulated food intake and the stress response to hunger [41]. Moreover, reduced insulin signaling in hungry flies triggers short neuropeptide F receptor (sNPFR) production to increase sNPF signaling, enhancing the response to odors [30].

3.3. Human Studies

A study investigated sensitivity to a non-food odor (n-butanol) and a food-related odor (isoamyl acetate) in 24 healthy women with normal olfactory function. The tests were conducted when participants were hungry and when they were satiated. Additionally, participants rated their emotional condition, arousal, and alertness, as well as the intensity and pleasantness of both odors. No significant changes were found in detection thresholds for the non-food odor of n-butanol; however, a significant change was observed in the detection threshold for the food-related odor of isoamyl acetate. Specifically, the detection threshold for isoamyl acetate was significantly lower in the satiated state compared to the hungry state. Interestingly, greater sensitivity was observed during the satiated state, challenging the current hypothesis that food intake control is supported by decreased sensitivity to food odors. These findings support the idea that both odor thresholds and odor-related pleasure play important roles in regulating food intake [28].
The first study to associate olfactory ability with nutritional status was conducted by Guild [42] and published in 1956. Using the Blast Injection Method, the study found that individuals with obesity exhibited lower olfactory sensitivity compared to non-obese subjects. A second study, conducted by Thompson [43], showed that individuals with normal weight and those with obesity did not differ in their hedonic response to sucrose (taste) or benzaldehyde (odor). Similarly, in Hubert’s 1980 study, olfactory sensitivity was measured in 97 pairs of twins, and total body fat percentage was found to be a factor associated with olfactory sensitivity [44]. In a study by Simchen et al. [45], participants with a BMI ≥ 28 kg/m2 were evaluated. Among participants under 65 years old, lower scores were observed in odor detection, odor identification, and taste perception. In contrast, in participants over 65 years old, higher scores were observed in those with a higher BMI.
Altered olfactory performance could affect food choice, which could promote overconsumption of food and, consequently, obesity in a modern food environment. Increased sensitivity to hypercaloric food odors has been observed in individuals with obesity, suggesting that the brain may amplify autonomic responses to highly rewarding foods [46,47,48,49].
On the other hand, a longitudinal study assessed olfaction and body composition in elderly people by means of the Brief Smell Identification Test. Participants with low olfactory ability had lower body weight and fat mass than those with high olfactory ability. According to longitudinal analyses, participants with poor olfaction lost more total weight and lean mass per year than those with good olfaction [50].

3.4. Studies in Children

There are fewer studies conducted on children. Obrebowski et al. [51] carried out a study on children/adolescents with and without obesity. In the group with simple obesity, significantly lower odor detection thresholds were observed (thresholds below the average for a given age group in approximately 20% of children/adolescents with obesity). Furthermore, it was noted that in cases of odors stimulating the olfactory nerve, around 57% of these children exhibited reduced sensitivity, especially for substances stimulating both the olfactory and trigeminal nerves. Odor identification thresholds were similarly affected, with the identification of odors stimulating the olfactory and trigeminal nerves being impaired more than twice as frequently as in non-obese counterparts.
Herz et al. [52] explored a group of adolescents aged 12 to 16 years old, of both sexes, classifying them based on early or late pubertal stages and BMI. The study found that participants in early puberty had significantly greater olfactory sensitivity compared to those in late puberty. Additionally, it was observed that adolescents with a higher BMI exhibited significantly greater olfactory sensitivity than those with a normal BMI.
Finally, a study evaluated the influence of pear and biscuit odors in normal-weight and obese children. The results showed that the impact of these odors on food choices varied according to body weight. In normal-weight children, pear and biscuit odors reduced the probability of choosing fruit, whereas in obese children, pear odor increased the probability of selecting fruit, with no significant effect of biscuit odor. Based on these findings, olfactory perception may influence food choices differently based on body weight [53].

3.5. Studies in Adults

Stafford’s study [54] included two experiments. The first study showed that odor sensitivity was greater in the unsatiated state compared to the satiated state, particularly in the group with a lower BMI. Conversely, the second study found that participants with a higher BMI exhibited greater sensitivity to food odors when satiated than unsatiated. In contrast, in participants with a lower BMI, there were no differences in odor sensitivity between the two states. In Skrandies’ study [39], participants of both sexes with varying BMIs were compared, revealing a decrease in olfactory sensitivity in individuals with a higher BMI.
In another study by Stafford [55], participants with and without obesity completed a standardized olfactory threshold test for an ecologically valid food-related odor (chocolate). The findings suggested that obese individuals exhibit greater olfactory sensitivity and preference for an odor associated with energy-dense foods (chocolate).
In Poessel’s study [27], 67 participants with varying BMIs were evaluated for olfactory ability using the Sniffin’ Sticks test and a food-associated odor test. Eating behavior measures were also assessed, and the olfactory bulb volume was measured using magnetic resonance imaging (MRI). No association was found between olfactory function and BMI; however, the volume of the olfactory bulb was significantly smaller in obese participants compared to those with normal weight. Additionally, an inverse correlation was observed between olfactory bulb size and BMI.
In Micarelli’s study [56], 221 participants of both sexes were evaluated and categorized into groups of normal weight, overweight, and Grade I and II obesity. Significant reductions were found in total scores and subtest scores for taste and smell in individuals with Grade I and II obesity compared to those with normal weight and overweight. Additionally, the frequency of nutrient intake showed a progressive increase across BMI stages. Significant associations were found between BMI and taste/smell subtests, as well as the intake of sugar, flavor, carbohydrates, saturated fats, monounsaturated fats, and polyunsaturated fats.
Richardson et al. (2004) reported that morbidly obese patients (n = 101, both sexes) with a BMI > 45 were more likely to have olfactory dysfunction compared to those with a BMI < 45. Specifically, individuals with a higher BMI were significantly more prone to experiencing absolute olfactory dysfunction or anosmia [57].
A study by Melis et al. [58] evaluated the effect of the rs2821557 polymorphism in the human Kv1.3 gene on olfactory function and BMI across different age groups. Additionally, various studies have shown that individuals with olfactory disorders report changes in their eating habits, favoring foods with stronger flavors and higher energy content, such as fats, sugars, spices, and salt, over foods like vegetables, which leads to increased body weight.
For example, in a study by Duffy et al. [59], 120 women were recruited, nearly half of whom (37 out of 80) had olfactory dysfunction. The following nutritional risk pattern was associated with lower olfactory perception: reduced interest in food-related activities (e.g., enjoying cooking or eating a wide variety of foods); lower preference for foods with sour/bitter flavors (e.g., citrus fruits) or spicy flavors (e.g., horseradish); higher intake of sweets; lower intake of low-fat dairy products; and a nutrient intake profile indicative of a higher risk of heart disease.
In the study by Manesse et al. [12], participants with quantitative olfactory impairment and control participants were recruited. They were asked to identify odors and rate them in terms of intensity, pleasantness, familiarity, irritation, and edibility. The researchers found that participants with reduced olfactory capacity were less attracted to new foods and tended to experience less pleasure while eating. Additionally, these participants used more condiments (e.g., sugar, sour cream, and mayonnaise) in their preparations to make their dishes more flavorful.
On the other hand, the study by Postma [60] recruited members of the Dutch Anosmia Foundation and control participants to assess adherence to the Dutch dietary guidelines. Participants with congenital loss of smell showed a greater preference for high-fat foods.
On the other hand, Brondel’s study [61] involved 144 adult participants of all nutritional statuses (BMI ranging from 17 to 39 kg/m2). They were offered six foods (cucumber and tomato, pineapple and banana, and peanut and pistachio) and asked to choose only one food based on their preference. Subsequently, they were offered all six foods, and olfactory and taste-related pleasure were evaluated. The results showed that after consuming a single food, specific sensory satiety (olfactory/taste) was correlated with the weight and volume of the food consumed, as well as the duration of ingestion, but not with the participant’s body weight. This suggests that both overweight and lean individuals have similar hedonic control of food intake when consuming simple foods.
In the study by Uygun [62], 52 women with obesity and 15 women with normal weight participated. After 8 h of fasting, ghrelin and leptin levels and a quantitative evaluation of olfactory function were measured. This included the n-butanol threshold test and an odor identification test using 12 “Sniffin’ Sticks screening 12 test” (Burghart, Wedel, Germany). The researchers found a positive correlation between serum ghrelin levels and n-butanol threshold scores in women with obesity. However, the Sniffin’ Sticks test scores were significantly lower in women with obesity compared to controls. Lastly, no correlation was observed between serum leptin levels and the Sniffin’ Sticks scores, n-butanol threshold, or sucrose taste threshold in women with obesity. This suggests that leptin, an anorexigenic peptide, may have a negative effect on taste and olfactory functions.

3.6. Eating Behavior Disorders

A study by Fernández-Aranda [63] also investigated the association between olfactory ability and ghrelin levels. The study recruited 239 women, including 64 with anorexia nervosa, 80 age-matched healthy-weight controls, 59 women with obesity, and 36 women with normal weight. The results showed that olfactory ability was differentially associated among the groups. Olfactory function was impaired in participants with obesity and enhanced in those with anorexia nervosa (hyposmia prevalence was 54.3% in obesity and 6.4% in anorexia nervosa). Ghrelin levels were significantly reduced in participants with obesity and were associated with impaired olfactory function. Olfactory ability and ghrelin may act as moderators of emotional eating and BMI.
The association between eating behavior disorders and olfactory function has also been studied. In Dazzi’s study [64], 19 patients with bulimia nervosa, 18 patients with anorexia nervosa, and 19 healthy controls were recruited. Olfactory function was evaluated using the ‘Sniffin’ Sticks’ method to assess olfactory threshold. Both bulimia nervosa and anorexia nervosa patients exhibited poorer olfactory and gustatory function compared to controls. Olfactory stimulus discrimination and overall olfactory function were reduced in both groups, while the olfactory threshold was specifically altered in patients with bulimia nervosa. In both groups, olfactory function scores fell within the range of hyposmia.
In Aschenbrenner’s study [65], 17 hospitalized patients with anorexia nervosa, 24 with bulimia, and 23 controls underwent olfactory tests to assess the effects of treatment on these measures. The findings showed that, upon discharge, anorexic patients had an increased BMI and significant improvement in overall olfactory and gustatory function.
In a study similar to the previous one, Schreder et al. [66] compared the olfactory sensitivity of 12 women with anorexia nervosa to 24 healthy controls. No differences were found in olfactory sensitivity to n-butanol. However, patients with anorexia nervosa had a significantly lower detection threshold for food-related odors, but only in the fasting condition. They also exhibited significant deficits in odor discrimination and identification and underestimated the pleasantness of isoamyl acetate. This reduced enjoyment of isoamyl acetate suggests a diminished olfactory response to food stimuli in anorexia nervosa.
However, some studies have not found such associations. For instance, in the study by Rapps [67], 19 participants with anorexia nervosa were compared to 21 controls, and no associations were found between BMI and olfactory ability.

3.7. Bariatric Surgery

In a study involving participants with morbid obesity, 55 individuals who underwent gastric bypass and cholecystectomy were compared to 40 individuals who underwent cholecystectomy (CC) alone. The Cross-Cultural Smell Identification Test (CC-SIT) was administered before surgery and 2 and 6 weeks after surgery. The results showed that olfactory function was not affected by weight loss [68].
A systematic review that included observational and experimental studies on individuals who underwent bariatric surgery found that, in addition to weight reduction, there was an improvement in olfactory impairment post-surgery [17]. Another systematic review reported similar findings, showing that bariatric surgery, particularly sleeve gastrectomy, significantly improved olfactory function [69].

3.8. Olfactory Dysfunction, BMI, and COVID-19

Olfactory dysfunction is among the side effects of COVID-19 infection [70,71]. This infection can cause quantitative olfactory dysfunction (hyposmia and anosmia) as well as parosmia, a qualitative dysfunction [72,73]. The latter results in altered odor perception, where pleasant smells are perceived as unpleasant, impacting food choices, reducing appetite, and affecting nutritional status [74,75].
An exploratory study in 9000 users in 2020 evaluated a thematic analysis of user-generated text from a Facebook support group on the loss of smell and taste due to COVID-19. Participants reported the following: difficulty explaining and managing an altered sense of taste and smell; lack of interpersonal and professional support; changes in eating habits; loss of appetite; changes in weight; loss of pleasure in eating foods, and social interaction; altered intimacy; altered relationship with self and others. The findings suggest that altered taste and smell due to COVID-19 can generate severe disruption of daily life, affecting psychological well-being, physical health, and relationships. Among the effects reported by participants were decreased desire and ability to eat and prepare food, weight gain, weight loss, and nutritional deficiency, and effects on emotional well-being, intimacy, social bonding, and altered sense of self and reality. Future research should take these findings into account and suggest areas for training, assessment, and treatment of healthcare professionals working with long-term COVID-19 [76].
However, associations with weight gain remain contradictory [77,78,79,80,81]. For example, a study evaluating behavioral changes in food intake and body weight during the COVID-19 pandemic showed that altered chemosensory perception (taste and smell) mainly induces a reduction in appetite, leading to a more rapid feeling of satiety during the consumption of a meal and, therefore, to a decrease in body weight [82].
In contrast to the above result, a study that included participants with COVID-19 conducted Sniffin’ Sticks testing and BMI assessments one year apart and found that participants with persistent olfactory dysfunction and self-reported parosmia showed statistically significant increases in BMI after 1 year. Controls with transient olfactory dysfunction and participants without parosmia showed no statistically significant changes in BMI over the same time period [83]. The authors hypothesize that the etiology of weight gain in patients with secondary olfactory dysfunction likely arises from altered eating patterns in the context of chemosensory dysfunction. A qualitative study (telephonic exploratory analysis) in individuals with COVID-19 showed that increased food intake was a compensatory response to the lack of food flavor [76]. This behavior may lead to an increased preference for palatable foods, which are generally high in sugar and fats [84].
An example of the above is a study that examined behavioral changes in food intake and body weight during the COVID-19 pandemic. There was an alteration in chemosensory perception (taste and smell), primarily resulting in a reduction in appetite, resulting in a faster feeling of satiety during meals and, therefore, a decrease in body weight [85].
It is important to note that the quality of evidence on this topic needs improvement. Future research should incorporate more precise measurements of body fat. First, many studies are based on small and non-representative samples, which makes it difficult to generalize the results, often lack control groups, and are not always randomized. In addition, most research is cross-sectional, which precludes establishing clear causal relationships between olfactory dysfunction and obesity. There is also a lack of standardization in the methods used to assess olfactory function, which may lead to inconsistent results. Finally, the influence of confounding factors such as diet, general health status, body composition, and medication use is not always adequately controlled for, which may lead to bias in the findings.

4. Conclusions

This narrative review elucidates the intricate relationship between olfactory function and obesity. Individuals with obesity often exhibit diminished olfactory sensitivity, influenced by hormonal imbalances such as elevated leptin and reduced ghrelin levels, which can lead to unhealthy food choices and increased consumption of calorie-dense foods. Additionally, olfactory dysfunction, including anosmia, prompts compensatory behaviors like seeking saltier or sweeter foods, further exacerbating obesity risk. The COVID-19 pandemic has also impacted olfactory function, leading to altered eating habits and preferences for less healthy options. The olfactory system’s role in energy regulation is underscored by its connection to the hypothalamus, which modulates appetite and satiety circuits. Animal and human studies reveal that olfactory sensitivity varies with nutritional states, affecting food choices and potentially promoting obesity. Addressing olfactory function in weight-loss programs could enhance their effectiveness, and further research is needed to elucidate the causal mechanisms between olfactory dysfunction, eating behavior, and obesity. A multidisciplinary approach involving neuroscience, psychology, and public health is essential for developing effective interventions to combat obesity.

Author Contributions

Conceptualization, A.M.O.-R. and S.D.-A.; methodology, A.M.O.-R. and S.D.-A.; writing—original draft preparation, A.M.O.-R. and S.D.-A.; writing—review and editing, A.M.O.-R. and S.D.-A. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Agencia Nacional de Investigación y Desarrollo ANID, Fondecyt Regular grant number 1231260 and The APC was funded by Agencia Nacional de Investigación y Desarrollo ANID.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Blüher, M. Obesity: Global epidemiology and pathogenesis. Nat. Rev. Endocrinol. 2019, 15, 288–298. [Google Scholar] [PubMed]
  2. NCD Risk Factor Collaboration. Trends in adult body-mass index in 200 countries from 1975 to 2014: A pooled analysis of 1698 population-based measurement studies with 19·2 million participants. Lancet 2016, 387, 1377–1396. [Google Scholar]
  3. World Health Organization (WHO). Noncommunicable Diseases. Available online: https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseases (accessed on 28 January 2025).
  4. World Health Organization. Noncommunicable Diseases Country Profiles 2018; World Health Organization: Geneva, Switzerland, 2018; p. 2018. [Google Scholar]
  5. Lara-Castor, L.; Micha, R.; Cudhea, F.; Miller, V.; Shi, P.; Zhang, J.; Sharib, J.R.; Erndt-Marino, J.; Cash, S.B.; Mozaffarian, D.; et al. Sugar-sweetened beverage intakes among adults between 1990 and 2018 in 185 countries. Nat. Commun. 2023, 14, 5957. [Google Scholar] [CrossRef] [PubMed]
  6. Miller, V.; Webb, P.; Cudhea, F.; Shi, P.; Zhang, J.; Reedy, J.; Erndt-Marino, J.; Coates, J.; Mozaffarian, D.; Global Dietary Database. Global dietary quality in 185 countries from 1990 to 2018 show wide differences by nation, age, education, and urbanicity. Nat. Food 2022, 3, 694–702. [Google Scholar]
  7. Spence, C. Multisensory Flavor Perception. Cell 2015, 161, 24–35. [Google Scholar]
  8. Micarelli, A.; Malacrida, S.; Strapazzon, G.; Mrakic-Sposta, S.; Micarelli, B.; Alessandrini, N.; Carbini, V.; Caputo, S.; Falla, M.; Alessandrini, M. Impact of Nutritional Intervention on Taste Perception-A Scoping Review. Foods 2021, 10, 2747. [Google Scholar] [CrossRef]
  9. McCrickerd, K.; Forde, C.G. Sensory influences on food intake control: Moving beyond palatability. Obes. Rev. 2016, 17, 18–29. [Google Scholar] [CrossRef]
  10. Yeomans, M.R. Olfactory influences on appetite and satiety in humans. Physiol. Behav. 2006, 89, 10–14. [Google Scholar]
  11. Reisenman, C.E.; Scott, K. Food-derived volatiles enhance consumption in Drosophila melanogaster. J. Exp. Biol. 2019, 222, jeb202762. [Google Scholar]
  12. Manesse, C.; Ferdenzi, C.; Sabri, M.; Bessy, M.; Rouby, C.; Faure, F.; Bellil, D.; Jomain, S.; Landis, B.N.; Hugentobler, M.; et al. Dysosmia-Associated Changes in Eating Behavior. Chemosens. Perception 2017, 10, 104–113. [Google Scholar]
  13. Roxbury, C.R.; Bernstein, I.A.; Lin, S.Y.; Rowan, N.R. Association Between Chemosensory Dysfunction and Diet Quality in United States Adults. Am. J. Rhinol. Allergy 2022, 36, 47–56. [Google Scholar] [CrossRef] [PubMed]
  14. Touhara, K.; Vosshall, L.B. Sensing odorants and pheromones with chemosensory receptors. Annu. Rev. Physiol. 2009, 71, 307–332. [Google Scholar] [CrossRef]
  15. Murphy, C. Nutrition and chemosensory perception in the elderly. Crit. Rev. Food Sci. Nutr. 1993, 33, 3–15. [Google Scholar] [PubMed]
  16. Drewnowski, A. Taste preferences and food intake. Annu. Rev. Nutr. 1997, 17, 237–253. [Google Scholar] [PubMed]
  17. Peng, M.; Coutts, D.; Wang, T.; Cakmak, Y.O. Systematic review of olfactory shifts related to obesity. Obes. Rev. 2019, 20, 325–338. [Google Scholar]
  18. Jovanovic, P.; Riera, C.E. Olfactory system and energy metabolism: A two-way street. Trends Endocrinol. Metab. 2022, 33, 281–291. [Google Scholar]
  19. Petrovich, G.D.; Setlow, B.; Holland, P.C.; Gallagher, M. Amygdalo-hypothalamic circuit allows learned cues to override satiety and promote eating. J. Neurosci. 2002, 22, 8748–8753. [Google Scholar] [CrossRef]
  20. Su, Z.; Alhadeff, A.L.; Betley, J.N. Nutritive, Post-ingestive Signals Are the Primary Regulators of AgRP Neuron Activity. Cell Rep. 2017, 21, 2724–2736. [Google Scholar]
  21. Timper, K.; Brüning, J.C. Hypothalamic circuits regulating appetite and energy homeostasis: Pathways to obesity. Dis. Models Mech. 2017, 10, 679–689. [Google Scholar] [CrossRef]
  22. Farr, O.M.; Li, C.-S.R.; Mantzoros, C.S. Central nervous system regulation of eating: Insights from human brain imaging. Metabolism 2016, 65, 699–713. [Google Scholar] [CrossRef]
  23. Quarta, C.; Claret, M.; Zeltser, L.M.; Williams, K.W.; Yeo, G.S.H.; Tschöp, M.H.; Diano, S.; Brüning, J.C.; Cota, D. POMC neuronal heterogeneity in energy balance and beyond: An integrated view. Nat. Metab. 2021, 3, 299–308. [Google Scholar] [PubMed]
  24. Kelley, A.E.; Baldo, B.A.; Pratt, W.E.; Will, M.J. Corticostriatal-hypothalamic circuitry and food motivation: Integration of energy, action and reward. Physiol. Behav. 2005, 86, 773–795. [Google Scholar]
  25. Vennemann, M.M.; Hummel, T.; Berger, K. The association between smoking and smell and taste impairment in the general population. J. Neurol. 2008, 255, 1121–1126. [Google Scholar] [CrossRef] [PubMed]
  26. Rohde, K.; Schamarek, I.; Blüher, M. Consequences of Obesity on the Sense of Taste: Taste Buds as Treatment Targets? Diabetes Metab. J. 2020, 44, 509–528. [Google Scholar]
  27. Poessel, M.; Breuer, N.; Joshi, A.; Pampel, A.; Villringer, A.; Hummel, T.; Horstmann, A. Reduced Olfactory Bulb Volume in Obesity and Its Relation to Metabolic Health Status. Front. Hum Neurosci. 2020, 14, 586998. [Google Scholar] [CrossRef] [PubMed]
  28. Albrecht, J.; Schreder, T.; Kleemann, A.M.; Schöpf, V.; Kopietz, R.; Anzinger, A.; Demmel, M.; Linn, J.; Kettenmann, B.; Wiesmann, M. Olfactory detection thresholds and pleasantness of a food-related and a non-food odour in hunger and satiety. Rhinology 2009, 47, 160–165. [Google Scholar]
  29. Soria-Gómez, E.; Bellocchio, L.; Reguero, L.; Lepousez, G.; Martin, C.; Bendahmane, M.; Ruehle, S.; Remmers, F.; Desprez, T.; Matias, I.; et al. The endocannabinoid system controls food intake via olfactory processes. Nat. Neurosci. 2014, 17, 407–415. [Google Scholar]
  30. Root, C.M.; Ko, K.I.; Jafari, A.; Wang, J.W. Presynaptic facilitation by neuropeptide signaling mediates odor-driven food search. Cell 2011, 145, 133–144. [Google Scholar]
  31. Savigner, A.; Duchamp-Viret, P.; Grosmaitre, X.; Chaput, M.; Garcia, S.; Ma, M.; Palouzier-Paulignan, B. Modulation of spontaneous and odorant-evoked activity of rat olfactory sensory neurons by two anorectic peptides, insulin and leptin. J. Neurophysiol. 2009, 101, 2898–2906. [Google Scholar] [CrossRef]
  32. Velluzzi, F.; Deledda, A.; Onida, M.; Loviselli, A.; Crnjar, R.; Sollai, G. Relationship between Olfactory Function and BMI in Normal Weight Healthy Subjects and Patients with Overweight or Obesity. Nutrients 2022, 14, 1262. [Google Scholar] [CrossRef]
  33. Palouzier-Paulignan, B.; Lacroix, M.-C.; Aimé, P.; Baly, C.; Caillol, M.; Congar, P.; Julliard, A.K.; Tucker, K.; Fadool, D.A. Olfaction under metabolic influences. Chem. Senses 2012, 37, 769–797. [Google Scholar] [CrossRef] [PubMed]
  34. Micarelli, A.; Vezzoli, A.; Malacrida, S.; Micarelli, B.; Misici, I.; Carbini, V.; Iennaco, I.; Caputo, S.; Mrakic-Sposta, S.; Alessandrini, M. Taste Function in Adult Humans from Lean Condition to Stage II Obesity: Interactions with Biochemical Regulators, Dietary Habits, and Clinical Aspects. Nutrients 2023, 15, 1114. [Google Scholar] [CrossRef]
  35. Wesson, D.W.; Wilson, D.A. Sniffing out the contributions of the olfactory tubercle to the sense of smell: Hedonics, sensory integration, and more? Neurosci. Biobehav. Rev. 2011, 35, 655–668. [Google Scholar] [CrossRef]
  36. Weismann, M.; Yousry, I.; Heuberger, E.; Nolte, A.; Ilmberger, J.; Kobal, G.; Yousry, T.A.; Kettenmann, B.; Naidich, T.P. Functional magnetic resonance imaging of human olfaction. Neuroimaging Clin. N. Am. 2001, 11, 237–250. [Google Scholar] [CrossRef]
  37. Wang, J.; Eslinger, P.J.; Smith, M.B.; Yang, Q.X. Functional magnetic resonance imaging study of human olfaction and normal aging. J. Gerontol. A Biol. Sci. Med. Sci. 2005, 60, 510–514. [Google Scholar] [CrossRef] [PubMed]
  38. Micarelli, A.; Mrakic-Sposta, S.; Micarelli, B.; Malacrida, S.; Misici, I.; Carbini, V.; Lennaco, I.; Caputo, S.; Vezzoli, A.; Alessandrini, M. Smell Impairment in Stage I-II Obesity: Correlation with Biochemical Regulators and Clinical Aspects. Laryngoscope 2022, 132, 2028–2035. [Google Scholar] [CrossRef] [PubMed]
  39. Skrandies, W.; Zschieschang, R. Olfactory and gustatory functions and its relation to body weight. Physiol. Behav. 2015, 142, 1–4. [Google Scholar] [CrossRef]
  40. Riera, C.E.; Tsaousidou, E.; Halloran, J.; Follett, P.; Hahn, O.; Pereira, M.M.A.; Ruud, L.E.; Alber, J.; Tharp, K.; Anderson, C.M.; et al. The Sense of Smell Impacts Metabolic Health and Obesity. Cell Metab. 2017, 26, 198–211.e5. [Google Scholar] [CrossRef]
  41. He, J.; Tuo, W.; Zhang, X.; Dai, Y.; Fang, M.; Zhou, T.; Xiu, M.; Liu, Y. Olfactory Senses Modulate Food Consumption and Physiology in Drosophila melanogaster. Front. Behav. Neurosci. 2022, 16, 788633. [Google Scholar] [CrossRef]
  42. Guild, A.A. Olfactory acuity in normal and obese human subjects: Diurnal variations and the effect of d-amphetamine sulphate. J. Laryngol. Otol. 1956, 70, 408–414. [Google Scholar] [CrossRef]
  43. Thompson, D.A.; Moskowitz, H.R.; Campbell, R.G. Taste and olfaction in human obesity. Physiol. Behav. 1977, 19, 335–337. [Google Scholar] [PubMed]
  44. Hubert, H.B.; Fabsitz, R.R.; Feinleib, M.; Brown, K.S. Olfactory sensitivity in humans: Genetic versus environmental control. Science 1980, 208, 607–609. [Google Scholar] [CrossRef]
  45. Simchen, U.; Koebnick, C.; Hoyer, S.; Issanchou, S.; Zunft, H.-J.F. Odour and taste sensitivity is associated with body weight and extent of misreporting of body weight. Eur. J. Clin. Nutr. 2006, 60, 698–705. [Google Scholar] [PubMed]
  46. Llewellyn, C.; Wardle, J. Behavioral Susceptibility to Obesity: Gene-Environment Interplay in the Development of Weight. Physiol. Behav. 2015, 152, 494–501. [Google Scholar] [CrossRef]
  47. Cecchetto, C.; Dal Bò, E.; Aiello, M.; Fischmeister, F.P.S.; Gentili, C.; Osimo, S.A. Alexithymia Modulates the Attitudes towards Odors but Not the Olfactory Abilities or the Affective Reactions to Odors. PLoS ONE 2023, 18, e0278496. [Google Scholar]
  48. Zoon, H.F.A.; de Graaf, C.; Boesveldt, S. Food Odours Direct Specific Appetite. Foods 2016, 5, 12. [Google Scholar] [CrossRef]
  49. Purdy, F.; Luo, Z.; Gardiner, J.C.; Pinto, J.M.; Shiroma, E.J.; Simonsick, E.M.; Harris, T.B.; Chen, H. Olfaction and Changes in Body Composition in a Large Cohort of Older U.S. Adults. J. Gerontol. A Biol. Sci. Med. Sci. 2020, 75, 2434–2440. [Google Scholar]
  50. Yuan, Y.; Li, C.; Luo, Z.; Simonsick, E.M.; Shiroma, E.J.; Chen, H. Olfaction and Physical Functioning in Older Adults: A Longitudinal Study. J. Gerontol. A Biol. Sci. Med. Sci. 2022, 77, 1612–1619. [Google Scholar] [PubMed]
  51. Obrebowski, A.; Obrebowska-Karsznia, Z.; Gawliński, M. Smell and taste in children with simple obesity. Int. J. Pediatr. Otorhinolaryngol. 2000, 55, 191–196. [Google Scholar]
  52. Herz, R.S.; Van Reen, E.; Gredvig-Ardito, C.A.; Carskadon, M.A. Insights into smell and taste sensitivity in normal weight and overweight-obese adolescents. Physiol. Behav. 2020, 221, 112897. [Google Scholar] [CrossRef]
  53. Marty, L.; Bentivegna, H.; Nicklaus, S.; Monnery-Patris, S.; Chambaron, S. Non-Conscious Effect of Food Odors on Children’s Food Choices Varies by Weight Status. Front. Nutr. 2017, 4, 16. [Google Scholar]
  54. Stafford, L.D.; Welbeck, K. High hunger state increases olfactory sensitivity to neutral but not food odors. Chem. Senses 2011, 36, 189–198. [Google Scholar] [CrossRef]
  55. Stafford, L.D.; Whittle, A. Obese individuals have higher preference and sensitivity to odor of chocolate. Chem. Senses 2015, 40, 279–284. [Google Scholar] [CrossRef]
  56. Micarelli, A.; Malacrida, S.; Vezzoli, A.; Micarelli, B.; Misici, I.; Carbini, V.; Caputo, S.; Mrakic-Sposta, S.; Alessandrini, M. Smell, taste and food habits changes along body mass index increase: An observational study. Eur. Arch. Oto-Rhino-Laryngol. 2023, 280, 5595–5606. [Google Scholar]
  57. Richardson, B.E.; Vander Woude, E.A.; Sudan, R.; Thompson, J.S.; Leopold, D.A. Altered olfactory acuity in the morbidly obese. Obes. Surg. 2004, 14, 967–969. [Google Scholar] [CrossRef]
  58. Melis, M.; Mastinu, M.; Sollai, G. Effect of the rs2821557 Polymorphism of the Human Kv1.3 Gene on Olfactory Function and BMI in Different Age Groups. Nutrients 2024, 16, 821. [Google Scholar] [CrossRef] [PubMed]
  59. Duffy, V.B.; Backstrand, J.R.; Ferris, A.M. Olfactory dysfunction and related nutritional risk in free-living, elderly women. J. Am. Diet Assoc. 1995, 95, 876–879. [Google Scholar]
  60. Postma, E.M.; De Graaf, C.; Boesveldt, S. Food preferences and intake in a population of Dutch individuals with self-reported smell loss: An online survey. Food Qual. Prefer. 2020, 79, 103771. [Google Scholar]
  61. Brondel, L.; Romer, M.; Van Wymelbeke, V.; Walla, P.; Jiang, T.; Deecke, L.; Rigaud, D. Sensory-specific satiety with simple foods in humans: No influence of BMI? Int. J. Obes. 2007, 31, 987–995. [Google Scholar]
  62. Uygun, B.; Kiyici, S.; Ozmen, S.; Gul, Z.; Sigirli, D.; Cavun, S. The Association Between Olfaction and Taste Functions with Serum Ghrelin and Leptin Levels in Obese Women. Metab. Syndr. Relat. Disord. 2019, 17, 452–457. [Google Scholar] [CrossRef]
  63. Fernández-Aranda, F.; Agüera, Z.; Fernández-García, J.C.; Garrido-Sanchez, L.; Alcaide-Torres, J.; Tinahones, F.J.; Giner-Bartolomé, C.; Baños, R.M.; Botella, C.; Cebolla, A.; et al. Smell-taste dysfunctions in extreme weight/eating conditions: Analysis of hormonal and psychological interactions. Endocrine 2016, 51, 256–267. [Google Scholar] [CrossRef] [PubMed]
  64. Dazzi, F.; De Nitto, S.; Zambetti, G.; Loriedo, C.; Ciofalo, A. Alterations of the olfactory-gustatory functions in patients with eating disorders. Eur. Eat. Disord. Rev. 2013, 21, 382–385. [Google Scholar] [CrossRef]
  65. Aschenbrenner, K.; Scholze, N.; Joraschky, P.; Hummel, T. Gustatory and olfactory sensitivity in patients with anorexia and bulimia in the course of treatment. J. Psychiatr. Res. 2008, 43, 129–137. [Google Scholar] [CrossRef] [PubMed]
  66. Schreder, T.; Albrecht, J.; Kleemann, A.M.; Schöpf, V.; Kopietz, R.; Anzinger, A.; Demmel, M.; Linn, J.; Pollatos, O.; Wiesmann, M. Olfactory performance of patients with anorexia nervosa and healthy subjects in hunger and satiety. Rhinology 2008, 46, 175–183. [Google Scholar]
  67. Rapps, N.; Giel, K.E.; Söhngen, E.; Salini, A.; Enck, P.; Bischoff, S.C.; Zipfel, S. Olfactory deficits in patients with anorexia nervosa. Eur. Eat. Disord. Rev. 2010, 18, 385–389. [Google Scholar] [CrossRef]
  68. Richardson, B.E.; Vanderwoude, E.A.; Sudan, R.; Leopold, D.A.; Thompson, J.S. Gastric bypass does not influence olfactory function in obese patients. Obes. Surg. 2012, 22, 283–286. [Google Scholar] [CrossRef] [PubMed]
  69. Matiashova, L.; Hoogkamer, A.L.; Timper, K. The Role of the Olfactory System in Obesity and Metabolism in Humans: A Systematic Review and Meta-Analysis. Metabolites 2023, 14, 16. [Google Scholar] [CrossRef]
  70. Saniasiaya, J.; Islam, M.A.; Abdullah, B. Prevalence of Olfactory Dysfunction in Coronavirus Disease 2019 (COVID-19): A Meta-analysis of 27,492 Patients. Laryngoscope 2021, 131, 865–878. [Google Scholar] [CrossRef]
  71. Tong, J.Y.; Wong, A.; Zhu, D.; Fastenberg, J.H.; Tham, T. The Prevalence of Olfactory and Gustatory Dysfunction in COVID-19 Patients: A Systematic Review and Meta-analysis. Otolaryngol. Head Neck Surg. 2020, 163, 3–11. [Google Scholar] [CrossRef]
  72. Gary, J.B.; Gallagher, L.; Joseph, P.V.; Reed, D.; Gudis, D.A.; Overdevest, J.B. Qualitative Olfactory Dysfunction and COVID-19: An Evidence-Based Review with Recommendations for the Clinician. Am. J. Rhinol. Allergy 2023, 37, 95–101. [Google Scholar] [CrossRef]
  73. Ercoli, T.; Masala, C.; Pinna, I.; Orofino, G.; Solla, P.; Rocchi, L.; Defazio, G. Qualitative smell/taste disorders as sequelae of acute COVID-19. Neurol. Sci. 2021, 42, 4921–4926. [Google Scholar] [PubMed]
  74. Chen, B.; Masala, C.; Oleszkiewicz, A.; Englmaier, V.; Gunder, N.; Menzel, S.; Haehner, A.; Hummel, T. Nonlinear association between chemosensory dysfunction and body mass index. J. Sens. Studies 2022, 37, e12715. [Google Scholar]
  75. Wysokiński, A.; Sobów, T.; Kłoszewska, I.; Kostka, T. Mechanisms of the anorexia of aging-A review. Age 2015, 37, 9821. [Google Scholar] [CrossRef] [PubMed]
  76. Burges Watson, D.L.; Campbell, M.; Hopkins, C.; Smith, B.; Kelly, C.; Deary, V. Altered smell and taste: Anosmia, parosmia and the impact of long COVID-19. PLoS ONE 2021, 16, e0256998. [Google Scholar] [CrossRef]
  77. Algahtani, S.N.; Alzarroug, A.F.; Alghamdi, H.K.; Algahtani, H.K.; Alsywina, N.B.; Bin Abdulrahman, K.A. Investigation on the Factors Associated with the Persistence of Anosmia and Ageusia in Saudi COVID-19 Patients. Int. J. Environ. Res. Public Health 2022, 19, 1047. [Google Scholar] [CrossRef]
  78. Perna, S.; Abdulsattar, S.; Alalwan, T.A.; Zahid, M.N.; Gasparri, C.; Peroni, G.; Faragli, A.; La Porta, E.; Ali Redha, A.; Janahi, E.M.; et al. A cross-sectional analysis of post-acute COVID-19 symptoms. Ann. Ig. Med. Prev. E Comunita. 2022, 34, 478–489. [Google Scholar]
  79. Taş, B.M.; Alpaydın, T.; Akçalı, S.; Kaygusuz, S.; Özlük Erol, Ö.; Şencan, Z.; Cömert, E.; Bayar Muluk, N.; Özel, G. Evaluation of Clinical Features and Olfactory Functions in COVID-19: A Multicentre Study. Cureus 2023, 15, e40027. [Google Scholar]
  80. Bhutani, S.; Coppin, G.; Veldhuizen, M.G.; Parma, V.; Joseph, P.V. COVID-19 related chemosensory changes in individuals with self-reported obesity. Rhinology 2022, 60, 128–138. [Google Scholar]
  81. Valladares Vega, M.; Obregón Rivas, A.M. Association of olfactory sensitivity with energy intake: Role in development of obesity. Nutr. Hosp. 2015, 32, 2385–2389. [Google Scholar]
  82. Ferrulli, A.; Senesi, P.; Terruzzi, I.; Luzi, L. Eating Habits and Body Weight Changes Induced by Variation in Smell and Taste in Patients with Previous SARS-CoV-2 Infection. Nutrients 2022, 14, 5068. [Google Scholar] [CrossRef]
  83. Vilarello, B.J.; Jacobson, P.T.; Tervo, J.P.; Gallagher, L.W.; Caruana, F.F.; Gary, J.B.; Saak, T.M.; Gudis, D.A.; Joseph, P.V.; Goldberg, T.E.; et al. BMI Increases in Individuals with COVID-19-Associated Olfactory Dysfunction. Nutrients 2023, 15, 4538. [Google Scholar] [CrossRef] [PubMed]
  84. Liem, D.G.; Russell, C.G. The Influence of Taste Liking on the Consumption of Nutrient Rich and Nutrient Poor Foods. Front. Nutr. 2019, 6, 174. [Google Scholar] [CrossRef] [PubMed]
  85. Chaaban, N.; Høier, A.T.Z.B.; Andersen, B.V. A Detailed Characterisation of Appetite, Sensory Perceptional, and Eating-Behavioural Effects of COVID-19: Self-Reports from the Acute and Post-Acute Phase of Disease. Foods 2021, 10, 892. [Google Scholar] [CrossRef] [PubMed]
Applsci 15 03590 g001
Figure 1. Flow diagram summarizing the article selection process.
Figure 1. Flow diagram summarizing the article selection process.
Applsci 15 03590 g001
Applsci 15 03590 g002
Figure 2. Smell and hypothalamic regulation of energy balance.
Figure 2. Smell and hypothalamic regulation of energy balance.
Applsci 15 03590 g002
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Durán-Agüero, S.; Obregón-Rivas, A.M. Olfactory Capacity and Obesity: A Narrative Review of the Literature. Appl. Sci. 2025, 15, 3590. https://doi.org/10.3390/app15073590

AMA Style

Durán-Agüero S, Obregón-Rivas AM. Olfactory Capacity and Obesity: A Narrative Review of the Literature. Applied Sciences. 2025; 15(7):3590. https://doi.org/10.3390/app15073590

Chicago/Turabian Style

Durán-Agüero, Samuel, and Ana María Obregón-Rivas. 2025. "Olfactory Capacity and Obesity: A Narrative Review of the Literature" Applied Sciences 15, no. 7: 3590. https://doi.org/10.3390/app15073590

APA Style

Durán-Agüero, S., & Obregón-Rivas, A. M. (2025). Olfactory Capacity and Obesity: A Narrative Review of the Literature. Applied Sciences, 15(7), 3590. https://doi.org/10.3390/app15073590

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop