What goes down need not go back up: decreasing the biological drive toward weight regain by increasing energy flux

Abstract

INTRODUCTION: Weight regain after weight loss is the experience of most obese dieters. Metabolic adjustments characterized by decreased resting metabolic rate (RMR) and increased hunger can prevent long-term success. Possibly this energy gap could be attenuated by a high flux (HF) state (higher expenditure coupled with higher intake). METHODS: 6 obese adults [age (mean±SE) = 42±12 y; body mass index (BMI)=35.7±3.7 kg/m2] underwent 7% diet-induced weight loss and were stabilized at this weight for 3 weeks. RMR via indirect calorimetry, and hunger via visual analog scale were then examined during two 4-day conditions of energy balance in random order--Low Flux (LF): sedentary with energy intake (EI)=RMR x1.35; and HF: daily exercise net energy cost of ~500 kcal/d and EI= RMR x1.7. RESULTS: Average 5-day weight did not differ between HF (103.4±4.7 kg) and LF (103±4.8 kg) (P>0.10). Average daily RMR was higher during HF (1926±138 kcal/day) compared to LF (1847±126 kcal/day; P = 0.05). Resting fat oxidation was also higher during HF (0.073+0.010 g/min) compared to LF (0.059+0.012 g/min; P<0.05). Average daily, perceived end-of-day hunger was lower during HF compared to LF (P<0.05). CONCLUSION: These preliminary data suggest that compared to a sedentary LF state of energy balance, a HF energy balance state is associated with a greater RMR, resting fat oxidation, and less hunger - all of which may attenuate the energy gap and protect against weight regain.