Leptin is a satiety factor in rodents. Mice
unable to produce leptin or with abnormal receptors are obese.
The administration of leptin results in weight loss with defective
In obese humans, however, leptin levels are elevated, consistent
with greater fat tissue. In general, the elevated leptin levels
decrease with weight loss. It is possible that this decrease
in leptin increases appetite
and consequent weight regain. Leptin is limited in its therapeutic
effectiveness because obese individuals exibit marked resistance
to the appetite-reducing effects of leptin.
Considine RV, Sinha MK, Heiman ML, Kriauciunas A, Stephens
TW, Nyce MR, et al (1996). Serum immunoreactive-leptin concentrations
in normal-weight and obese humans. N Engl J Med;334:292-5.