Effects of age and short-term fasting on plasma leptin in obese women and its association with some metabolic cardiovascular risk factors

ABSTRACT

The study included 22 female obese subjects with body mass index [BMI] ranged from 32-43 Kgm/m2 and age 20-56 years. The effect of 24 h fasting on serum leptin, insulin, and glucose was determined. Also, the correlation between serum leptin and some metabolic risk factors for cardiovascular disease such as lipoproteins and abdominal visceral fat was evaluated. We found that the magnitude of decrease in leptin concentration. with 24 h fasting was much greater than the possible associated loss of body weight induced by fasting. This suggests that other factors modulate leptin secretion other than total adipose mass. The ability of progressive fasting to suppress plasma leptin levels despite a minimal change in adipose mass suggests that ongoing caloric deficiency supersedes total energy reserve in setting chronic levels of satiety and thermogenesis. This regulatory mechanism might have conferred a survival advantage in environments characterized by rapid changes in food availability. Significant correlations were found between abdominal visceral fat measured by computed tomography [CT] and total serum cholesterol, HDL-cholesterol, and triglycerides. However, no association was found between plasma leptin concentrations and both abdominal visceral fat and waist/hip ratio. Also, there was no association between plasma leptin and plasma lipid concentrations. Since plasma leptin concentrations were not related to alterations of plasma lipoprotein concentrations and abdominal visceral which are known risk factors for cardiovascular disease, it does not seem relevant to include leptinemia in the set of metabolic risk factors for cardiovascular disease. Circulating leptin level reflects total adipos tissue mass rather than a combination of adipose tissue mass and distribution