Abstract
BACKGROUND/OBJECTIVES: Energy expenditure (EE), as reflective of body energy demand, has been proposed to be the key driver of food intake, possibly influencing weight change in humans. Variation in this energy-sensing link (overeating relative to weight-maintaining energy requirements) may lead to weight gain over time. SUBJECTS/METHODS: Sixty-one overweight otherwise healthy Native Americans (age: 34.0 ± 7.9 years, body fat: 39.7 ± 9.5%, 36 males) were admitted to our clinical research unit for measurements of body composition by dual-energy X-ray absorptiometry, and 24-h EE and respiratory quotient (RQ) in a whole-room indirect calorimeter during energy balance and weight stability. Following this, ad libitum food intake was assessed for three days using computerized vending machines. Body weight change under unrestricted free-living conditions was assessed at an outpatient follow-up visit (median follow-up time = 1.7 years). RESULTS: Total ad libitum food intake (3-day average) was positively associated with 24-h EE (r = 0.44, p < 0.001), RQ (r = 0.34, p = 0.007), and fat free mass (r = 0.38, p = 0.002). A relatively greater food intake after accounting for 24-h EE, but not for RQ (p = 0.30) or for fat free mass (p = 0.23) nor total food intake (p = 0.16), predicted weight gain at the outpatient follow-up visit (r = 0.26, p = 0.04), such that overeating 100 Kcal/d above the food intake predicted by 24-h EE at baseline was associated with an average weight gain of 0.22 Kg over the follow-up period (95% CI: 0.01 to 0.42 Kg). This was due to relatively greater dietary fat intake (r = 0.32, p = 0.01), but not carbohydrate (p = 0.27) or protein (p = 0.06) intake. CONCLUSION: The individual propensity to overeating, particularly fat, in excess of the weight-maintaining energy requirements can be assessed and predicts long-term weight gain, suggesting that variation in energy sensing may influence appetite by favoring overeating thus promoting obesity development.