We investigated whether weight gain alters insulin sensitivity and leptin levels in
physically active individuals. Six (5 males and 1 female; age 26.6 ± 1.0 years; BMI
21.5 ± 0.9, body fat 17.4 ± 2.2%) healthy individuals were enrolled in an over-feeding
study (caloric surplus 22.5 - 26.5 kcal/kg/day) to achieve up to 10% weight gain over
4 - 6 week period with subsequent weight maintenance over additional 2 weeks. The
participants were requested to maintain their previous physical activity which in
all of them included 45 - 60 mm training sessions at the gym 2 - 3 times/week. Results:
BMI increased to 23.4 ± 0.9 (4.4 kg weight gain; p < 0.05) and body fat to 21.0 ±
2.8% (p < 0.05) over the period of active weight gain and remained stable over the
two week period of weight maintenance; fasting plasma glucose and serum insulin remained
unchanged; serum leptin nearly doubled (3.8 ± 1.0 vs 6.4 ± 1.9 ng/mL; p < 0.05); insulin
sensitivity, when expressed per kg of the total body (11.1 ± 1.6 vs 12.4 ± 2.1 mg/kg/mm;
p = NS), and lean body mass (13.4 ± 1.9 vs 15.7 ± 2.6 mg/kgLBM/min; p = NS), did not
decrease after weight gain. On the contrary, insulin action had improved in 5 out
of 6 individuals. In conclusion, the data presented in this preliminary report indicate
that a small weight gain due to overfeeding in lean, healthy, physically active individuals
is associated with rise in circulating leptin levels but not with worsening of insulin
action.
Key words
Weight Gain - Insulin Resistance - Leptin
