Reprinted from Eating Disorders Review
January/February 2007 Volume 18, Number 1
©2007 Gürze Books
In the quest for ways to counteract obesity, numerous researchers have searched for naturally occurring hormones or chemicals that might promote or reduce the incidence of obesity. One of these is peptide YY (PYY), an intestinal peptide that is believed to be a satiety factor. Early studies suggested that low plasma PYY levels may contribute to diet-induced human obesity and justify PYY replacement therapy. However, according to the results of a recent study, PYY may not be an effective advance toward effective anti-obesity treatment, and there may be no PYY deficiency in obesity (J Endocrin Metab 2006; 10:1425).
Dr. P.T. Pfluger and co-workers in Germany and Australia measured total PYY levels in 18 female patients with anorexia nervosa; 63 obese persons (20 males, 43 females); 66 lean subjects(24 males, 42 females); and 16 morbidly obese subjects (1 male, 15 females). In addition, total PYY was measured in 17 of the obese patients after weight loss and in the 19 anorectic patients after weight gain.
The researchers found that fasting total plasma PYY levels were highest in patients with anorexia nervosa (80.9 picograms per milliliter [pg/ml]), compared to lean (52.4 pg/ml), obese (43.9 pg/ml), or morbidly obese subjects (45.6 pg/ml). In obese patients, losing 5.4% of body weight was associated with a 30% decrease in fasting total PYY plasma levels. In patients with anorexia nervosa, weight gain had no effect on fasting PYY levels.
Thus, the authors’ findings do not support a role for abnormal circulating PYY levels in human obesity. Instead, they concluded that circulating PYY levels in humans are significantly elevated in anorexia nervosa and, given the controversially discussed anorectic effect of PYY, could theoretically contribute to that syndrome.