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Effectiveness and Characterization of Severely Energy-Restricted Diets in People with Class III Obesity: Systematic Review and Meta-Analysis

1
The Boden Collaboration for Obesity, Nutrition, Exercise & Eating Disorders, Charles Perkins Centre, Faculty of Medicine and Health, The University of Sydney, Sydney 2006, Australia
2
Metabolism & Obesity Services, Royal Prince Alfred Hospital, Sydney 2006, Australia
3
Faculty of Medicine and Health, School of Pharmacy, The University of Sydney, Sydney 2006, Australia
4
School of Life, and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney 2006, Australia
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Behav. Sci. 2019, 9(12), 144; https://doi.org/10.3390/bs9120144
Received: 13 October 2019 / Revised: 24 November 2019 / Accepted: 3 December 2019 / Published: 7 December 2019
Severely energy-restricted diets are used in obesity management, but their efficacy in people with class III obesity (body mass index ≥40 kg/m2) is uncertain. The aims of this systematic review and meta-analysis were to determine the effectiveness and characteristics of severely energy-restricted diets in people with class III obesity. As there was a lack of publications reporting long-term dietary interventions and randomised controlled trial designs, our original publication inclusion criteria were broadened to include uncontrolled study designs and a higher upper limit of energy intake. Eligible publications reported studies including adults with class III obesity and that assessed a diet with daily energy intake ≤5000 kJ for ≥4 weeks. Among 572 unique publications from 4 databases, 11 were eligible and 10 were suitable for meta-analysis. Our original intention was to classify comparison arms into short-term (<6 months) and long-term (>1 year) interventions. Due to the lack of long-term data found, comparison arms were classified according to the commonalities in dietary intervention length among the included publications, namely dietary interventions of 4 weeks’ duration and those of ≥6 weeks’ duration. After a 4-week severely energy-restricted diet intervention, the pooled average weight loss was 9.81 (95% confidence interval 10.80, 8.83) kg, with a 95% prediction interval of 6.38 to 13.25 kg, representing a loss of approximately 4.1 to 8.6% of initial body weight. Diets ≥6 weeks’ duration produced 25.78 (29.42, 22.15) kg pooled average weight loss, with a 95% prediction interval of 13.77 to 37.80 kg, representing approximately 10.2 to 28.0% weight loss. Daily dietary prescriptions ranged from 330 to 5000 kJ (mean ± standard deviation 2260 ± 1400 kJ), and had wide variations in macronutrient composition. The diets were administered mostly via liquid meal replacement products. While the included publications had a moderate risk of bias score, which may inflate reported weight loss outcomes, the published data to date suggest that severely energy-restricted diets, delivered via diets of varying composition, effectively produce clinically relevant weight loss (≥10% of initial body weight) when used for 6 weeks or more in people with class III obesity. View Full-Text
Keywords: obesity; morbid; diet; reducing; meta-analysis; meta-regression; weight loss treatment; low-energy liquid diet obesity; morbid; diet; reducing; meta-analysis; meta-regression; weight loss treatment; low-energy liquid diet
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Maston, G.; Gibson, A.A.; Kahlaee, H.R.; Franklin, J.; Manson, E.; Sainsbury, A.; Markovic, T.P. Effectiveness and Characterization of Severely Energy-Restricted Diets in People with Class III Obesity: Systematic Review and Meta-Analysis. Behav. Sci. 2019, 9, 144.

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