Many any people who suffer from overweight and obesity go on diets that restrict their calories, which initially leads to weight loss, however the majority of these dieters regain the weight. The body is able to detect a low amount of calories consumed, and will therefore increase levels of ghrelin, a hormone that stimulates hunger; and decrease levels of leptin in our body, a hormone that tells us to stop eating. This mechanism works to keep the body’s weight regulated, and can be problematic for overweight and obese people who are trying to lose weight.
It is not known whether changes in levels of ghrelin and leptin that occur during weight loss are sustained with prolonged maintenance of reduced weight. This concept is important for understanding weight regain after weight loss.
50 men and post-menopausal women that classify as overweight or obese.
For 8 weeks, participants replaced their daily meals with a very low calorie dietary formula and 2 cups of low starch vegetables. At the end of week 10, they consumed a diet designed to maintain their weight. Participant’s body composition and blood levels were measured at weeks 0 and 10, and again one year after, during fasting and after intake of a meal.
Subject lost 14% of their weight after 10 weeks and at one year had partially regained what had been lost. When subjects lost weight, leptin decreased, and ghrelin and appetite increased. This indicates that internal cues in the body are signaling food intake after weight loss. Researchers also found that after weight loss, energy expenditure remained decreased for one year, meaning that the body is burning less calories doing day-to-day activities, another barrier to weight maintenance.
The drop out rate for this study was high, so the 1-year results were only for the 16 remaining participants. The form of measurement was not optimal. Additionally, the possibility that weight loss may alter the brains sensitivity to circulating hormones was not examined. This may have indicated that changes in hormonal levels may be countered by changes in brain sensitivity to the hormones, though it is unknown.
The high rate of relapse among obese people who have lost weight is not simply the result of voluntary resumption of old habits, but has a strong, uncontrollable, physiological basis. In obese people who have lost weight, multiple compensatory mechanisms encouraging weight gain must be overcome in order to maintain weight loss. Methods to overcome these compensatory mechanisms and prevent weight regain should be addressed in future studies.
The full text, titled “Long-Term Persistence of Hormonal Adaptations to Weight Loss. It is in the 2011 issue of The New England Journal of Medicine. 365:1597-604.The authors are Sumithran, P., Prendergast, L., Delbridge., B., Purcell, K., Shulkes, A., Kriketos, A., and J. Proietto.
Written by Angela Misko and Hilary Kasman, Dept. Nutritional Sciences, Rutgers University-NewBrunswick Edited by SA Shapses, PhD, RD