History of Slimming Diets up to the Late 1950s

: Nowadays, obesity is a pandemic, and some people seek slimming diets to guarantee their health and quality of life. However, the cult of the healthy body has been an ongoing concern since the beginning of time. Irrespective of the century to which they belong, these cults reﬂect no empirical knowledge about physiology, nutrients or kilocalories, with some of them being quantitative diets in contrast to qualitative diets, or even simple food recommendations. On the other hand, some of these treatments might have led to the death of a patient, meaning that it is important for people seeking to lose weight to be followed by a nutrition professional until the individual reaches a desirable body weight. In this article, we highlight that each century and each decade have devised different treatments with the aim of improving health, but it will be science and history that will judge whether the results of these treatments have been adequate.


Introduction
Obesity is a global epidemic which has serious implications in terms of public health, and which causes social and economic problems [1]. However, nutrition is a recent science, developed thanks to studies conducted by Lavoisier and Atwater in the 18th and 19th centuries, respectively [2]. Throughout history, there have been non-scientific approaches to guaranteeing weight loss through the use of miracle, magic or hazardous diets [3]. This article addresses the trajectory of slimming diets throughout the centuries, from the first known treatments to those described in the 1950s, using PubMed, Google Scholar, and Web of Knowledge. Furthermore, this strategy was complemented with a comprehensive search of the 'white', 'grey' and 'black' literature, using four different searching strategies: (i) grey literature databases, (ii) customized Google search engines, (iii) targeted websites and (iv) consultation with contacted experts.

Diets before Christ (BC)
The importance of treatments involving weight loss has been known since ancient times. In fact, fifteen types of diets have been identified during this period, one being developed in China and two from India. The remaining ancient diets were developed in the Mediterranean region. The unique Chinese treatment is commonly known as Shen Nong's diet, who was the Yellow Emperor in the Han dynasty from c. 2695 BC, and who initiated the consumption of green tea to reduce obesity, this illness being associated with the nobleman and rich people due to the ingestion of heavy and greasy foods [4]. Nowadays, it is considered to be the first historic diet. As for India, Susruta's diet was performed by this Indian physician in around 600 BC, and he observed the problem of a sedentary lifestyle, and established exercise [5] and fasting or an Ayurvedic diet [6] to improve the quality of life. Furthermore, he was the first to link diabetes mellitus (associated with choosing a "reckless diet" and symptoms including obesity, voracity, a soporific tendency and an inclination to take a break in a bed or on a cushion) with heart disease and obesity [7]. On the other hand, an Indian physician called Charak, from c. 300 BC, developed the treatment that bears his name, and he was the most famous exponent of Ayurvedic medicine, and related obesity with an excessive intake of heavy, sweet, cooling and unctuous food, a want of physical exercise, day sleep, uninterrupted cheerfulness or a lack of mental exercise [8]. Iason [9] suggested, in the Ayurveda, that the consumption of testicular tissue could work against obesity, but this intake was not reflected in Charak's recommendations.
If one moves into the Mediterranean influence, the oldest is the Spartan diet (also known as Lycurgus's diet), which had a crucial role in promoting health in this society, banishing obesity from the people of Sparta. Law-giver Lycurgus (c. 900-800 BC) legislated that the human body should be kept away from laziness, muscular weakness and obesity throughout the population [10]. This was the first public health promotion campaign to reverse the obesity phenomenon. Other diets emerged in the Mediterranean basin, such as:

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Pythagoras's diet. He was an Ionian philosopher (570-495 BC) who recommended eating in moderation due to the fact that several fellow citizens overate and vomited or fasted [11]. • Iccus's diet (or the repast of Iccus). He born in Taranto (fifth century BC) and was a physician focused on the combination of exercise with a frugal diet to guarantee health and quality of life. It is known that the "repast of Iccus" is based on a plain and temperate meal [12]. • Herodicus's diet. He was a physician in the fifth century BC and is considered to be the father of sports medicine, who recommended the need to regulate diet and exercise and prescribed repeated brisk 42 km walks from Athens to Megara at progressively increasing speeds in some patients. In fact, Hippocrates and Plato indicated that he caused the death of several individuals by submitting them to excessively long walks and forced exercise [13].

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Herodotus's diet. The Greek historian (480-429 BC) reflected on how Egyptians vomited and purged themselves thrice every month, with a view to preserve their health, which in their opinion is chiefly injured by their food [14].

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Hippocrates's diet. Hippocrates of Kos (460-370 BC) was recognized as the father of modern medicine, which is based on observations of clinical signs and rational conclusions. One of them is focused on obesity and its associated increased risk of sudden death being counterbalanced with severe physical labor before breakfast and the avoidance of wine unless largely diluted with water [15]. • Polybus's diet. He was the pupil of Hippocrates and also his son-in-law (c. 400 BC), and he recommended a drying diet and to exercise fasting, drinking small, slightly warm liquors and eating only once a day to satisfy hunger [16]. • Aristotle's diet. He was a philosopher (384-322 BC) who suggested that the right quantity of foods produces, increases or preserves health and quality of life [17]. • Diocles's diet. He was a Greek physician (240-180 BC), who indicated that obese people should eat only once per day [18]. • Asclepiades's diet. He was a Greek physician born in Prusa (120-40 BC) who made claims about the importance of drink, food and enemas and who recommended diet, exercises, thermal treatments, cold baths and drinking wine as principal therapeutics [19]. • Diodorus Siculus's diet. He wrote the monumental Bibliotheca historica, in forty books, between 60 and 30 BC. In the first book, which is focused on the history and culture of Ancient Egypt, he proposed a method to reduce food absorption which involved "purging, vomiting or fasting every second, third or fourth day". It was justified using the following phrase: "the greatest part of the food we take is superfluous, which superfluity is cause of our distempers" [20]. • Celsus's diet. He was Greek philosopher (around 25 BC), who recommended overall moderation in diet, and who treated obesity by sea-bathing. Furthermore, he promoted the induction of vomiting with an excess of food [21].

Diets from the First Anno Domini (AD) to the End of the 18th Century
The diet of the Papyrus Insinger is contained in this document, which is maintained at the Rijksmuseum van Oudheden in Leiden, and which is dated to the first century AD and contains around 800 maxims established as one-liners, similar to a proverb, organized into numbered chapters [22]. One of them is focused on the personal responsibility for the moderation of diet, which is reflected as "illness befalls a man because the food harms him. He who eats too much bread will suffer illness". On the other hand, Egyptian doctors established the need to adopt an adequate diet as a necessary means to preserve the health of the individual, recognizing the importance of both the quantity of food and its quality [23].
Dioscorides's diet was established by the father of pharmacology (40-90 AD) and written in a medical and pharmaceutical encyclopedia called De materia medica. He used, to emaciate obese bodies, three elements called "Asian meadow" (its dried flowers were used as a cataplasm to suppress the great amount of flesh), unsalted cheese (to emaciate the flesh) and mustard (to remove phlegm from the body and to emaciate it) [24]. A few years later, Soranus of Ephesus (98-138 AD) suggested a combination of diet and exercise, baths, venesection, purging and a radical change in the way of living to prevent obesity [25] and Aelianus's diet, created by Claudius Aelianus (170-235 AD), who was a Roman sophist. He wrote the historic first case report to be applied in slimming diets for a patient called Dionysius of Heraclea, which was undertaken as an operation by the physicians, being described as follows: "doctors prepared very long, thin needles and pushed them through the hips and belly of Dionysius when he had fallen into a deep sleep. They inserted the needles from top to bottom into the insensitive (and, so to say, alien) flesh of the tyrant. Dionysius had no reaction; but when the needle reached a point that was healthy and part of his system, which was not insensible from excess fat, he reacted and woke up" [26].
Oribasius's diet is outlined in the great medical encyclopedia composed of 70 books and suggested as a treatment of obesity, modifying the "temperament" from moist to warm, in conjunction with exercise, medications, baths, massage, the provocation of "mental anxiety" (to dry the temperament up and emaciate the body) and diet, with this latter meaning to eat only once a day and to use diuretics (including the seed and tops of wild rue, round birthwort, small centaury, gentian, poley and Macedonian parsley) [27]. This treatment was recommended by other authors, such as Aetius of Amida (sixth century AD) [28] and Paulus Aegineta (625-690 AD) [29]. Interestingly, Galen of Pergamum (129-200 AD) [30], who was the physician of Roman emperors, laid out the first classification of obesity. Furthermore, he suggested treating obesity with intense running, hot baths, light food in proportion to the exercise performed and increased physical work. Likewise, he also associated the use of diuretics and massage with oils [31]. Obesity as an illness in the Galenic notion was based on an imbalance of the humors. However, this was refuted 1300 years later by Paracelsus, a Swiss physician, who proposed that improper diet had a part to play in obesity [32].
From the fifth century, a Greek physician called Anthimus wrote "The Dietetics", in which he advised Christians to eat and drink in moderation, arguing that selected foods should be easily digestible [33]. On the other hand, the Patriarch of Constantinople, John Chrysostom (or John of Antioch) wrote, around 300 AD, about how the correct and incorrect diet should be and suggested the reduction of food intake and the performance of a regular fast, since eating until satiety is the mother of disease and ill health [34].
The Byzantine doctor, Alexander of Tralles (also known as Alexander Trallianus) (~525-605 AD), established his Trallianus's diet, which was taken up by the book entitled Therapeutics, and defined obesity as an illness produced by one or more of the following three options [35]: (1) Extreme frigidity of the temperament together with phlegm concentration. The treatment should induce satiation and reduce hunger, taking the opposites of cold to be unmixed wine and very fatty foods, such as the legs of pheasants and pork meat. (2) Extreme heat of the temperament. The treatment recommended neither use of wine, nor ingestion of indigestible food or food with cooling properties, such as that made of peppers, fish sauce prepared with water and the ankles, breasts, vulvas and feet of cows. (3) As a result of frigidity or warmth of the temperament, obesity is a malfunction of the "retentive" faculty. For this reason, the treatment of a cold dyscrasia should involve medicaments that bring warmth, especially those based on massage, cataplasms (containing gum laudanum, aloe and absinth), drink (with rhubarb and ginger) and foods, such as vegetables, cabbage that is thrice-boiled and seasoned with wine, the stem of turnips, barley groats, the porridge of rice groats, wheat with wine and einkorn, birds (partridge or goose), meats (lamb and venison) and dried raisins. However, if the affection is due to a warm dyscrasia, then he recommends bread, hard-boiled eggs (eaten around 3 p.m.), vegetables (endive, lettuce and mallow), birds (chicken and pheasant breast or leg), fish (sea perch, wrasse, piper, octopus and cuttlefish), shellfish (lobsters and trumpet shells and those with a spiral shell and pectens), beans, broad beans, rice and fruits (sweat apples, citrus fruits, hard-fleshed grapes, melons, the pith of figs, mulberry and walnuts are the most useful fruits).
Protospatharius's diet (ninth century AD) recommended phlebotomy as a pillar of an appropriate process of nourishment for the human body [36], while Al-Razi's diet was designed by the Persian polymath (854-925 AD), who practiced and wrote books, such as Benefits of food and the warding off of its harmfulness and Encyclopedia of Medicine. The treatment of weight loss was based on diet, drugs, exercises, massage, hydrotherapy and lifestyle changes [37].
For Arabic medicine, the figure of Avicenna (also called Abu Ali Ibn Sina) (980-1037 AD) is remarkable. He recommended three pillars to reduce weight, namely, hard exercise, lean food and sleep, together with a mixture of appetite suppressants, including sweet almonds, beef suet, violets and marshmallow [38]. The use of these pillars was suggested by Ibn Hubal Al-Baghdadi (1121-1213 AD), who emphasized the performance of hard exercise with an empty stomach [39]. Further to the east, the most outstanding treatment is the diet of "The Four Tantras" included in the classical Tibetan medical compendium dating back to the twelfth century AD, or even earlier, and containing 156 chapters and 5900 verses focused on the preventive, remedial and rejuvenating characteristics of food [40]. Obesity is reflected on as an illness that shortened the life span, with the treatment focused on catabolism, involving massage with pea flour, the eating of wolf flesh and the use of enemas and compresses [41].
Almost 80 years later, Sir Thomas Elyot (1490-1546 AD), who was diplomat, wrote The Castel of Health, wherein he reflected on recommendations for a healthy diet and overall lifestyle, making him one of the pioneers of promoting the primary prevention of disease, emphasizing the dangers of overeating [42].
A remarkable phenomenon in the late 1500s/early 1600s that was based on a religious fervor coupled with prolonged fasts gave rise to the so-called "miracle maidens" or "fasting girls", which is a phenomenon of self-starvation based on not ingesting any type of food for long periods of time, and which some followers based on the Christian tradition as a sign of holiness [43]. In 16th century Germany, a fasting maiden was executed when it was discovered that she was actually eating in secret [44]. It was only later that the prominent British physician William Withey Gull coined the term anorexia nervosa in 1874 in relation to this peculiar form of self-starvation [45].
From the 16th century to the end of the 18th century, several treatments had appeared, including: • Cornaro's diet. Luigi Cornaro (1464-1566 AD) was a Venetian nobleman who created the "Immortality Diet", outlined in his writing called Four Discourses on a Sober Life, wherein he recommended a restriction of food intake (about 340 g of food/day consisting of 12 ounces of food and 14 ounces of wine) to the minimum needed for survival, and to eat only food that agreed with the body's constitution [46]. It is worth mentioning, to conclude this section, that the German doctor Christoph Hufeland introduced this diet in Europe through his book Macrobiotics; or, the art of prolonging human life [56], while the belief that it could cure cancer was introduced in the middle of the 1960s by a Japanese prophet, philosopher and lecturer named George Ohsawa [57]. In the USA, it is established by a student from Ohsawa named Michio Kushi, who was an advisor of the Federation of Natural Medicine [58]. It is a diet based on the principle of balance between yin and yang, which, in the East, the foods that contain more potassium or sodium are referred to, respectively. Yin foods are classified as expansive, light and cold foods, while yang foods are dense, heavy and hot. The foods allowed are whole grains (to the detriment of refined ones), millet or soy soup, vegetables, legumes, a small number of fish per week (excluding meats, eggs and dairy products), local fruit, unrefined vegetable oil and desserts in moderation. In the macrobiotic system, there are ten stages, ranging from −3 to +7; the first five (from −3 to +2) involve decreasing amounts of foods of animal origin, while the other five (from +3 to +7) are exclusively vegetables, and as the number of the diet increases, vegetable foods are excluded and cereals increase. It promises weight losses of up to 1.25 kg/week. The most dangerous thing about this diet is to be in stage +7, or cereal, which the Council of Foods and Nutrition of the American Medical Association and the Committee on Nutrition of the American Academy of Pediatrics have condemned because it can lead to deficiencies, together with the appearance of scurvy, anemia, hypoproteinemia (decreased serum protein concentration), hypocalcemia (an electrolyte imbalance with a low blood calcium level) and loss of kidney function due to low fluid intake, and can eventually lead to death [59].

Diets during 19th Century
One diet was developed during the 19th century by the English poet George Gordon Byron (known as Lord Byron), who was a key figure in Romanticism who had several health problems, including lameness, faintness, giddiness and gonorrhea, among others [60], and it has been hypothesized that the poet suffered from malaria [61] and bulimia or the anorexia eating disorder [62], with this last illness reflected in his most subversive epic poem entitled Don Juan and emulated with the consumption of Epsom salts, magnesia and strong laxatives to purge and vomit [63]. He carried out a crash diet based on the consumption of only a quarter of a pound of butcher's meat in only one meal a day over 24 h, and little quantities of wine [64]. At the age of 23, he bought [65] William Wadd's book [66] (which adapted the strategy of weight loss established by Coelius Aurelianus) and adapted different diets as follows: (i) "leguminous-eating Ascetic", (ii) potatoes, vegetables and cookies, without wine and (iii) "hard biscuits and soda water". However, he passed the final years of his life eating a diet of vinegar (to lessen his appetite), water and rice as a result vomiting and diarrhea as a side effect of vomiting. In fact, he experienced a reduction of his BMI from 29.7 to 22.1 kg/m 2 from 1806 to 1822, respectively [67]. The slim and pale appearance of the poet were defining aspects of Romanticism, and his appearance was emulated by lovers of this cultural movement. His diet based on the consumption of vinegar has become very popular in the twenty-first century. Interestingly, its adverse impacts were even reflected on in 1733, when Pierre Desault published the first case report on a French woman, called Mademoiselle Lapaneterie, who died one month later following the consumption of vinegar as a slimming diet [68].
The French physician and physiologist Claude Bernard, the founding father of experimental medicine, was the discoverer of glycogen as the storage form of sugar in the body. In 1862, he made a presentation in Paris to explain the role of the liver in diabetes, with the otolaryngologist William Harvey among the attendees, who had William Banting as a patient; Banting was London's most famous funeral director and was responsible for the famous sarcophagus for the Duke of Wellington, made with a rare granite called luxullianite, which is in St. Paul's Cathedral in London. Banting goes, due to his deafness, to Dr. Harvey, indicating that the affectation could be due to diabetes and, based on the speech heard from Dr. Bernard, Harvey suggests that he follow a diet based on the considerable reduction of starches and sugars, eating three daily meals based on fish or meat with vegetables and some fruit, avoiding bread, beer, sweets, milk and potatoes, allowing Banting to lose 16 kg in the first year and 25 the next. In view of the success, Banting writes down his diet on a pamphlet (with the name "Letter on Corpulence"), which exists now as Banting's diet [69]. The success of this publication is such that the Anglo-Saxon public relates the concept of Banting or to bant with "being on a diet", and Banting donated the equivalent of approximately EUR 400 to Dr. Harvey to be distributed among some hospitals [70]. It is considered to be the first low-carbohydrate diet, for which there is evidence of the first known diet book being published.
In 1898, a businessman named Horace Fletcher managed to lose 18 kg by chewing every bite of food, even up to 100 times, being nicknamed by the population as "the great chewer" [71]. He decided to publish a book that soon became a best-seller [72], giving rise to two new terms; Fletcherism and Fletcherizing, corresponding to Fletcherism (a diet that follows the principles of Horace Fletcher) and Fletcherization (the act of chewing according to Fletcherism), respectively. One of the greatest fans of this new technique, which he applied at the Battle Creek Spa, was Dr. John Harvey Kellogg, the inventor of breakfast cereals. However, Fletcher preached something a little more extreme: he believed that we should chew each bite without swallowing it until the food became liquid (which is a bit complicated for many foods). The truth is that the act of chewing is a process that, due to the stressful life we lead, is not carried out properly. Food is swallowed rather than chewed. If it were performed properly, slowly and with an adequate duration, one of the effects that would be observed is that it causes a feeling of satiety; therefore, less food would be ingested, resulting in a lower ingestion of kilocalories and, therefore, it would help with weight loss. These data are reflected in a study, carried out in 2011 by researchers from Oxford Brookes University [73], comparing two groups of participants, wherein one of them performs the chewing process 35 times per bite, compared to those who perform it 10 times, testing to see whether the first group are those who reach their state of satiety earlier.
At the end of the 19th century, pills with arsenic content began to be used under the banner of "accelerating the metabolism", with this being known as "Arsenic diet" [74]. Although their concentration was small, they were still dangerous, especially for those people who, desperate to lose weight, took more pills than normal.

Diets from the First Decade of the 20th Century to the End of the 1950s
The 20th century began, surprisingly, with the "Tapeworm diet", which was advertised as being effortless: it involved the ingestion of a capsule that contained the parasite known as a tapeworm, and had the motto that its ingestion was free of side effects. This was a tremendous error, since the presence of this parasite in the organism can cause abdominal pain and discomfort, cramps, colic, diarrhea, nausea, dizziness, vomiting, vertigo, headache, tiredness, malabsorption, anorexia, muscle pain, constipation, vitamin deficiency, anemia, intestinal obstruction, perforation jejunal, appendicitis and pancreatitis [75]. To make the diet more famous, it was said that singer María Callas used it, but the truth is that she did have this parasite, but not by consciously ingesting these capsules, but by accidentally consuming the parasite in raw meat [76]. This treatment, together with the urine diet, are two of the first diets that involve products that are not food.
On the other hand, in the 19th century, the French biologist Claude Bernard had already observed that the change from the herbivorous diet of rabbits to a carnivorous one leads to a change in urine pH, changing it from being more alkaline to being more acidic, and it was not until the first decades of the 20th century, after Dr. Hay's diagnosis of Bright's disease (a degenerative nephritis), when he started to monitor his diet, seeing it improving three months later. As a result of these results, he worked on the development of a diet (called the "Alkaline diet") [77], whereby he said that he could achieve good health if he achieved a perfect balance, and whereby the proteins and carbohydrates are digested in an acidic and alkaline environment, respectively. It promised weight loss of 1.5 kg per week. With all this, he proposed, through conferences and with one of his best-selling books, that human beings are acquiring, through a poor diet with the consequent presence of a high number of acidic fluids in the human body, a number of chronic diseases (including arthritis and rheumatism) unknown to their ancestors. He separated the foods in two categories, acids (such as meat, fish, milk, cow, sugar or alcohol) and alkalis (vegetables and fruits), and argued that the more adequate diet would be composed of 80 and 20% alkaline and acidic foods, respectively. In 2001, the research group of Dr. Klaus Dieter Wutze [78] from the University of Rostock in Germany, carried out a study with twelve healthy adults who received a normal individualized diet, and subsequently ten days of Hay's diet, observing that the latter did not reduce the amount of total body water, nor even lean body mass, body fat and body weight. In 2002, Dr. Young rescues the idea of this diet and is faithfully followed by many after his publication The pH Miracle [79]. Dr. Young argues that the human body is alkaline, and that disease is acidosis that causes cancer, obesity, osteoporosis, flu, skin problems and other diseases, and for this reason he promotes the alkaline diet, associated with a life with low levels of stress. To date, the only certainty is that there are certain foods that can modify the pH, but mostly that of urine. For example, the consumption of purines (a nitrogenous compound found in organ meats) can be transformed in the body by uric acid crystallizing in the joints and producing gout, in addition to forming kidney stones. The modification of the pH of blood (which is between 7.40 and 7.45), although it occurs in our organism, is self-regulating. To all this, we must add that there is no scientific evidence that the use of an alkaline diet can reduce obesity, with none provided even by Dr. Young, as indicated by the National Council against US Health Fraud [80]. To this must be added that Dr. Young has been accused of practicing medicine without a license in terms of both nutrition and oncology, along with an acknowledgement of the rain of criticism he received after the death of a woman named Kim Tinkham, who was diagnosed with breast cancer. She adopted the therapeutic protocols of Dr. Young, who recommended that it be followed by other patients with this type of cancer. The woman died four weeks later from this disease [81].
In 1918, Lulu Hunt Peters published the first best-selling diet book in the USA, Diet and Health: with key to the calories [82], which is based on a scientific view (according to Atwater's literature published in 1894, as the first published guidance on dietary advice by the United States Department of Agriculture [83]).
During the 1920s, Benjamin Gayelord Hauser, a graduate of naturopathy and chiropractic medicine, developed a diet, which carries his name, that is based on consuming daily foods from each of the seven groups according to the tastes of each one and respecting the groups and foods that comprise it [84]. These seven groups are as follows: one (juice of natural fruit), two (tomato juice and carrot juice), three (infusions of herbs, including chamomile, horsetail, star anise or peppermint, among others), four (fat-burning soup, whose ingredients are a cup of celery, a cup of carrots, half a cup of spinach, a cup of tomato juice, a teaspoon of parsley and a little salt, cooked over a low heat and passed through a blender), five (yogurt and skim milk), six (fresh vegetables, including carrots, lettuce, bell pepper, celery, parsley, asparagus, tomato, onion, eggplant, cauliflower, cabbage and garlic, among others) and seven (fresh fruit, especially pineapples, oranges, watermelon, grapefruit, grapes, pears and apples, but not bananas) [85]. With his brother-in-law, he began to market his products for use in patients, and in parallel made his way into Hollywood using his diet on the great stars of that time, such as Fred Astaire, Ingrid Bergman, Marlene Dietrich, Greta Garbo, Paulette Goddard, Grace Kelly, Jeanne Moreau, Gloria Swanson and the Duchess of Windsor. He was called a nutrition advisor, since he did not have a medical degree, nor was he a doctor. He promised weight losses of up to 1.5 kg per week. It is a hypoenergetic diet, which can cause an insufficient supply of vitamins and minerals. In the same decade, a mucusless diet was popularized by the German naturopath, Arnold Ehret, who defends in his book, published in 1922 [86], the implementation of the mucusless diet (which allows one not to produce mucus) to improve the health condition. To achieve this, he proposed a healing system composed of various types of raw and cooked fruits and vegetables that allow the blood to be alkalized. Nowadays, there is no scientific publication that supports its success. Together with the above, Johanna Brandt, a prophet and naturopath influenced by the writings of Arnold Ehret, and after being assured that she had been cured of stomach cancer, published a book focused on a diet containing grapes [87], and recommended the ingestion of this fruit (between 2 and 4 kg/day) for a week, stating that one could lose up to 1 kg/day. Other diets with fruit (although it may be better known as the Hollywood Diet or the 18-Day diet, from an unknown artist), and, in particular, with grapefruit, became popular in the early 1930s, with proponents stating that this fruit contains an enzyme capable of burning fat, which, ingested daily as part of a low-calorie diet (500-800 kcal), could help lose weight [88]. It promised 2 kg of weight loss per week, although it may cause dizziness and fatigue due to a lack of carbohydrates, in addition to causing bone decalcification and damaged kidneys. In 1970, it resurfaced again with the hippy era, but, in this case, it was the US Department of Agriculture who promoted it because, that year, they had a surplus of that fruit. In fact, some components in grapefruit do favor the oxidation of these fats, such as p-synephrine, and scientists from the Camilo José Cela University [89] have demonstrated that the substance is capable of accelerating this process during intense exercise. However, as the study is very recent, it requires more trials.
A few years later, we see the appearance of Dr. Shelton's diet [90]. Herbert McGolfin Shelton studied at the American School of Chiropractic, graduating as a Doctor of Naturopathy from the American School of Naturopathy. The premise of his diet is also based on the concept of dissociation, and although he began specifically writing for vegetarians, it was modified to increase his patients to non-vegetarians. It promises weight losses of up to 1.5 kg per week. From 1927, and for the next three decades, he was arrested, imprisoned and fined for practicing medicine without a license, to which must be added the accusation of homicide by negligence by starving one patient, with another dying from a heart attack. Due to the sentence, he originated his own financial bankruptcy [91].
It is interesting to see the diet of Reverend Emmet Fox, who was a Minister of the Church of Divine Science and the author of the book The Seven Day Mental Diet [92], published in 1935. It is a diet that was not designed specifically for weight loss, but the goal is, by changing the mind (especially one's thoughts), to cause the conditions of life to change as well. He argues that it is the food that is provided to the mind that completely determines the character of life. The treatment has a duration of a week, and involves the construction of positive, constructive thoughts to be more optimistic and friendly and, in this way, it will lead to a modification in the style of life.
In this period, the Waerland cure was introduced by the Finnish health ideologist, Are Waerland, who proposed in his book, So heals Waerland [93], a diet that does not exceed 600 kcal that should be performed for two days, with the result of being able to lose up to 3 kg. The diet contains acidic dairy, flax seeds, celery and tubers (carrot and potato) and fresh spring water, comprising, according to the author, an alkalizing diet.
The last diet of this review is the cider vinegar-based diet, found in the book entitled Folk Medicine: A Vermont Doctor's Guide to Good Health [94], published in 1958 by the general practitioner, DeForest Clinton Jarvis. Jarvis argues that its consumption favors the acidity of the body compared to its alkalinity and, among other effects, facilitates the elimination of fats. One of the drawbacks of its consumption is that, taken on a regular basis, it can cause some irritation in the throat. In 1998, a group of researchers from the Department of Internal Medicine of the University Hospital of Innsbruck (Austria) [95] found that high consumption of this vinegar can cause hypocalcemia, hyperreninemia (a high level of renin in the blood) and osteoporosis (bone disease characterized by a decrease in tissue density osseous). In addition, there is a clinical case of a 15-year-old girl who suffered erosive dental wear due to the ingestion of a daily glass of cider vinegar [96].
Finally, this decade gave us the book entitled Eat Well and Stay Well [97], which was reissued a few years later with the title How to Eat Well and Stay Well the Mediterranean Way [98]. This book includes tips on how to reduce the risk of coronary heart disease with various recipes for the preparation of dishes similar to those consumed in Mediterranean countries. On 16 November 2010, the Mediterranean Diet was declared an Intangible Cultural Heritage of Humanity [99], in the joint name of Spain, Greece, Italy and Morocco, and today, it is considered to be a gold health standard of diet for weight loss [100].

Conclusions
This historic review, with the extensive number of diets reflected upon from throughout the centuries, demonstrates that many of them were developed by non-sanitary people from charlatans to actresses, even passing over enlightened people. It has to be pointed out that the fame of some treatments goes beyond the concept of a diet, and they are renamed with the person responsible for their creation, such as the Fletcherism. Treatments for weight loss must be carried out by nutrition professionals to ensure their effectiveness and to make sure that they do not pose a risk in terms of health because some of them have resulted in death. Furthermore, this article reflected on diets that focus on food recommendations or treatments (quantitative or qualitative), which complicates a detailed assessment and comparison about kilocalories or the quantity of macro-and micro-nutrients. Finally, it is convenient to paraphrase Hippocrates and say to the reader of this article: "Let food be thy medicine, and let medicine be thy food, but please remember that the diet should be carried out by a nutrition professional". Your health and quality of life will be thankful for it.