Body fat predicts an increase and limb muscle strength predicts a decrease in leptin in older adults over 2.6 years

Objective: Obesity is characterised by hyperinsulinemia, which is associated with diabetes, hypertension and coronary heart disease. The aim of this study was to determine if body fat and muscle measures predict the natural increase in leptin over 2.6 years in older adults.

Methods: 190 subjects (50% females) aged between 50 to 79 years were selected to perform the serum measurements for leptin. Height and weight were measured and body mass index (BMI) was calculated. Fat and lean mass of the whole body and the trunk were acquired through dual energy X-ray absorptiometry (DXA). Leg muscle strength and handgrip strength were measured using dynamometry.

Results: In multivariable analyses, leg muscle strength was negatively associated with both baseline leptin (β: -0.05 μg/l per Kg, 95% CI: -0.08, -0.02) and follow-up leptin (β: -0.04 μg/l per Kg, 95% CI: -0.07, -0.01). BMI, and percentage total fat and trunk fat and their respective change per annum (cpa) were significantly and positively associated with leptin. Lean mass was negatively associated with baseline leptin. Gender specific analyses produced similar associations between leg muscle strength, fat measures and follow-up leptin in males and females.

Conclusion: Besides positive associations between body fat, trunk fat and leptin, we found that leg muscle strength was negatively associated with leptin after 2.6 years in a sample of older population. This suggests interventions to maintain or increase muscle strength may have a protective effect on hyperleptinemia.