Leptin is influenced both by predisposition to obesity and diet composition

(1) To investigate whether plasma leptin concentrations differ between subjects with and without the genetic predisposistion to obesity, and (2) to investigate the effect of dietary manipulations on plasma leptin in these subjects.

Fasting and postprandial plasma leptin concentrations were measured before and after 14 days' ad libitum intake of a fat-rich (FAT), starch-rich (STARCH) or sucrose-rich (SUCROSE) diet. On day 15 ad libitum breakfast and lunch were given and blood sampled regularly until 6 p.m.

Eight normal-weight, post-obese women and 10 matched controls (body mass index, 23.5+/-0.5 and 22.9 +/- 0.3 kg/m2).

Leptin, glucose, insulin, appetite ratings, dietary intake, body weight and composition.

Fasting leptin concentration on day 1 or 15 did not differ between post-obese and controls. However, after meal intake leptin increased in post-obese compared with controls on all three diets. In both groups fasting and postprandial leptin concentrations were greater after SUCROSE compared with FAT and STARCH.

A larger postprandial leptin concentration was observed in post-obese subjects than in controls. This may be related to greater insulin sensitivity in adipose tissue in the post-obese. Furthermore, increased leptin concentrations were found after a sucrose-rich diet in both groups, possibly related to larger postprandial insulin peaks on this diet. Both contentions should, however, be validated by further studies.