A comparison of serum leptin concentrations in obese and normal weight Japanese women with regular menstrual cycle

Leptin is a protein that is synthesized and secreted from adipose tissue. We examined the changes in serum leptin level during the menstrual cycle in 5 normal and 5 obese Japanese women, and compared the data with those of serum estradiol (E2) and progesterone (P4) concentrations. Serum leptin levels were highly correlated with body mass index (BMI) and percent body fat, being higher in the obese group than in the normal group. In the obese group, serum leptin level increased in the luteal phase in parallel with the rise in the serum E2 level. In the normal group, however, there was no significant change in serum level during the menstrual cycle. These results suggested that the serum leptin levels were influenced by the phase of menstrual cycle, probably through the action of E2, in different ways for obese and non-obese women.