Lean male high- and low-fat phenotypes--different routes for achieving energy balance

This study investigated how energy expenditure may contribute to energy balance in lean male individuals consuming a diet either high or low in fat.

Fifteen high-fat phenotypes (HF) and 15 low-fat phenotypes (LF) participated in the study. Energy intake and macronutrient intake variables were assessed using a food frequency questionnaire and 3 day food diaries. Total energy expenditure (TEE) was estimated from 24h heart rate monitoring and factorial methods. Habitual physical activity was measured using the Baecke questionnaire.

There were no anthropometric differences between HF and LF. HF had a significantly higher heart rate over 24 h; this was particularly evident during the sleeping phase. There were no differences in TEE between HF and LF, but HF were more sedentary than LF.

In these young male subjects a high fat intake was associated with increased sedentariness; however, higher heart rates (basal and post-meal) could indicate that energy balance was achieved by relatively high basal metabolism and an increase in dietary-induced themogenesis (physiological route). In contrast LF could maintain energy balance through relatively high levels of physical activity (behavioural route).