Lower “Awake and Fed Thermogenesis” Predicts Future Weight Gain in Subjects With Abdominal Adiposity

Abstract

Awake and fed thermogenesis (AFT) is the energy expenditure (EE) of the nonactive fed condition above the minimum metabolic requirement during sleep and is composed of the thermic effect of food and the cost of being awake. AFT was estimated from whole-room 24-h EE measures in 509 healthy subjects (368 Native Americans and 141 whites) while subjects consumed a eucaloric diet. Follow-up data were available for 290 Native Americans (median follow-up time: 6.6 years). AFT accounted for ∼10% of 24-h EE and explained a significant portion of deviations from expected energy requirements. Energy intake was the major determinant of AFT. AFT, normalized as a percentage of intake, was inversely related to age and fasting glucose concentration and showed a nonlinear relationship with waist circumference and BMI. Spline analysis demonstrated that AFT becomes inversely related to BMI at an inflection point of 29 kg/m2. The residual variance of AFT, after accounting for covariates, predicted future weight change only in subjects with a BMI >29 kg/m2. AFT may influence daily energy balance, is reduced in obese individuals, and predicts future weight gain in these subjects. Once central adiposity develops, a blunting of AFT may occur that then contributes to further weight gain.

Long-term weight status in regainers after weight loss by lifestyle intervention: status and challenges

“…Experimental reductions in sleep duration support the claim that sleeping time could alter metabolic rates or affect the levels of appetite regulatory hormones such as leptin and ghrelin (30) . An association between insufficient sleep and increased energy intake has been demonstrated in some studies (29)(30)(31) . Sleep restriction was associated with an increase in energy consumption with no change in energy expenditure through PA or leptin and ghrelin concentrations (32) .…”

Higher Daily Energy Expenditure and Respiratory Quotient, Rather Than Fat-Free Mass, Independently Determine Greater ad Libitum Overeating

“…Multivariable regression models were used to calculate the residuals of EE parameters (24-hour EE and RQ, SMR and AFT) after accounting for known covariates, as previously described (11,24,25). The Pearson's correlation coefficient (r) was used to quantify the associations between EE residuals and food intake measures.…”

“…The Pearson's correlation coefficient (r) was used to quantify the associations between EE residuals and food intake measures. Based on the previously reported nonlinear relationship between AFT and BMI showing an inflection point at a BMI ϭ 29 kg/m 2 (11), the relationships between residuals of AFT and food intake measures were calculated separately in subjects with a BMI below and above 29 kg/m 2 .…”

“…Sleeping EE (SMR) accounts for approximately 70% of 24-hour EE (10), suggesting that SMR might explain part of the relationship between 24-hour EE and food intake. The "awake and fed" thermogenesis (AFT) is defined as the nonactivity related increase in sedentary EE over SMR that includes the cost of being awake and TEF, representing the overall thermogenic response to necessary physiologic activities related to survival (11). Given the importance of meal consumption in real-life settings, it is important to evaluate the metabolic response to feeding in relation to daily energy intake.…”

Weight Regain Following Intentional Weight Loss in Older Adults

“…Sleeping and resting energy expenditure were measured in women before and after a weight loss of >10 kg and results indicated that black women had lower body composition-adjusted energy requirements than white women during sleep which could predispose them to greater weight regain [20]. The difference in energy expenditure in the fasting, sleeping state, and the nonactive fed sedentary condition was examined after a 6-year period in over 500 young, healthy subjects [21]. Although this study did not include a weight loss intervention to examine weight regain, awake and fed thermogenesis predicted future weight gain in obese individuals, especially those with high waist circumference and hence abdominal obesity.…”