The high-fat phenotype: is leptin involved in the adaptive response to a high fat (high energy) diet?

OBJECTIVE: To investigate physiological differences which could influence the balance between energy expenditure and energy intake, between habitual high-fat (HF) and low-fat (LF) consumers and the potential for weight gain. SUBJECTS: Ten HF and nine LF consumers, all young, lean males (% energy from fat 45.4 and 31.8, respectively). MEASUREMENTS: Habitual dietary variables (from the food frequency questionnaire, FFQ), body mass index (BMI), % body fat (% BF, measured by impedance), fasting concentrations of plasma leptin, glucose and triglycerides. RESULTS: HF and LF subjects (selected for their fat intake) did not differ significantly in BMI or % BF. HF subjects had significantly higher concentrations of plasma leptin and lower concentrations of plasma glucose than LF subjects. In all subjects, concentrations of fasting plasma leptin correlated significantly with BMI, % BF and fat mass; difference in leptin between groups remained significant when BMI and % BF were used as covariants. Leptin significantly correlated with dietary variables; particularly dietary fat (% energy and g) and inversely with dietary carbohydrate (% energy), but showed no correlation with dietary protein or total energy intake. CONCLUSION: Significant differences in concentrations of fasting plasma leptin have been observed between lean male HF and LF consumers. These findings suggest that the difference in leptin concentrations could be associated with a metabolic adaptation which could help to offset the weight inducing properties of high fat (high energy) diets.