Leptin treatment of obese men reduces appetite but not body weight

Sustained weight maintenance after significant weight loss is usually difficult to achieve. One potential pharmacological approach to the treatment of obesity involves leptin, a circulating hormone that is released by the body's fat cells. Leptin provides a signal to the central nervous system to regulate appetite, food intake, and other aspects relevant to weight management. In a study of middle-aged obese men published in the American Journal of Clinical Nutrition, Westerterp-Plantenga et al. investigated the effects of leptin on appetite and energy expenditure during a moderate weight loss diet. The treatment group that received weekly injections of the leptin protein experienced subjective changes in appetite. However, reductions in calorie intake and body composition were similar to the untreated group.

The 30 healthy men averaged 45 years old and were obese with an average BMI of 34.2. Once a week for 12 weeks, a treatment group of 15 participants was given an injection of a form of leptin that had been chemically modified to reduce immune response. A placebo group received injections of an inert solution. Both groups were counseled to follow a mildly restricted diet of 2,100 calories per day. Daily appetite profile, calorie intake, energy expenditure, body mass index, and serum leptin concentrations were measured at regular intervals. Appetite and hunger decreased in the treatment group but increased in the placebo group from day 1 of the study. The leptin-treated subjects had significantly less desire to eat, had lower estimates of how much food they expected to consume, and reported greater feelings of fullness throughout the entire period. However, the lower appetite ratings in the treatment group were recorded in a fasting state before breakfast, and were not associated with actual reduced food intake either at breakfast or dinner, during which the subjects ate as much as they wished. At the conclusion of the study after 12 weeks, the treatment group had lost an average of 4.3 kg, while the placebo group had lost an average of 6.4 kg, without significant differences between the groups. Serum leptin levels in the treatment group had risen modestly as a result of the injections. In the placebo group, serum leptin had fallen significantly, which is a normal response to weight loss.

The authors suggest that intravenous leptin failed to reduce food intake because reduced appetite and subjective feelings of hunger during the fasting state were not representative the rest of the day.

Westerp-Plantenga, Margriet S, et al. Effects of weekly administration of pegylated recombinant human OB protein on appetite profile and energy metabolism in obese men. Am J Clin Nutr 2001;74:426-34.

This media release is provided by The American Society for Clinical Nutrition to provide current information on nutrition-related research. This information should not be construed as medical advice. If you have a medical concern, consult your doctor. To see the complete text of this article, please go to:

http://faseb.org/ajcn/October/12124-Westerterp.pdf

For more information, please contact: westerterp@hb.unimaas.nl

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