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Physiological Effects

Metabolic and hormonal responses to weight loss hold patients back from losing weight and keeping it off, despite their best efforts.  

The tug-of-war of weight management

Willpower vs biology: Metabolic and hormonal responses affect ability to maintain weight loss1,2

Graphic depicting conflicting factors contributing to weight loss and weight gain

After weight loss, metabolic adaptation may result in increased signals for energy intake (increase in the hunger hormone [ie, ghrelin] and decrease in satiety hormones [eg, GLP-1, PYY, CCK, amylin]).1,2

Patients were randomized to calorie restriction (CR), calorie restriction with exercise (CREX), or low-calorie diet (LCD) groups. Mean percent weight change (SEM) at six months by group was: -10.4 (0.9)% (CR), -10.0 (0.8)% (CREX), and -13.9 (0.7)% (LCD) of initial body weight.3

What obesity does to the body

Weight loss triggers multiple processes that defend baseline body weight and make it very difficult to maintain weight loss2

These mechanisms contributing to weight regain persist for at least 1 year.

Mean (±SE) changes in weight following initial weight loss

Graph depicting mean changes in weight following initial weight loss from a 62-week study

Study design

Study enrolled 50 patients with BMI of 27 to 40 kg/m2 who were prescribed a very low-calorie diet (500-550 kcal/day) for 8 weeks, followed by individual counseling from a dietitian for 1 year with the aim of weight maintenance and suggested 30 minutes of physical activity on most days of the week. Circulating levels of appetite-regulating hormones were measured at weeks 10 and 62 and were compared with baseline levels.2

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Study enrolled 50 patients with BMI of 27 to 40 kg/m2 who were prescribed a very low-calorie diet (500-550 kcal/day) for 8 weeks, followed by individual counseling from a dietitian for 1 year with the aim of weight maintenance and suggested 30 minutes of physical activity on most days of the week. Circulating levels of appetite-regulating hormones were measured at weeks 10 and 62 and were compared with baseline levels.2

A review of 14 long-term studies showed that people with obesity regained weight after weight loss achieved by dieting4

A review of 14 long-term studies showed that people with obesity regained weight after weight loss achieved by dieting
A review of 14 long-term studies showed that people with obesity regained weight after weight loss achieved by dieting

Study design

Study participants’ weight and diet statuses were assessed at baseline; then their weight was measured at follow-ups for up to 7 years after the diet ended. These data are from a review of 14 diet studies with long-term follow-ups. Adapted from Mann T, Tomiyama AJ, Westling E, Lew AM, Samuels B, Chatman J. Medicare’s search for effective obesity treatments: diets are not the answer. Am Psychol. 2007;62(3):220-233.4

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Study participants’ weight and diet statuses were assessed at baseline; then their weight was measured at follow-ups for up to 7 years after the diet ended. These data are from a review of 14 diet studies with long-term follow-ups. Adapted from Mann T, Tomiyama AJ, Westling E, Lew AM, Samuels B, Chatman J. Medicare’s search for effective obesity treatments: diets are not the answer. Am Psychol. 2007;62(3):220-233.4

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1. Lam YY, Ravussin E. Analysis of energy metabolism in humans: a review of methodologies. Mol Metab. 2016;5(11):1057-1071.

2. Sumithran P, Prendergast LA, Delbridge E, et al. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011;365(17):1597-1604.

3. Heilbronn LK, de Jong L, Frisard MI, et al. Effect of 6-mo. calorie restriction on biomarkers of longevity, metabolic adaptation and oxidative stress in overweight subjects. JAMA. 2006;295(13):1539-1548.

4. Mann T, Tomiyama AJ, Westling E, et al. Medicare's search for effective obesity treatments: diets are not the answer. Am Psychol. 2007;62(3):220-233.