Energy compensation and adiposity in humans

Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1-3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response-energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity

Human total, basal and activity energy expenditures are independent of ambient environmental temperature

Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (−10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average Ta and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p < 0.01) relationships between TEE, BEE and Ta emerged in females but the effect sizes were not biologically meaningful. Temperatures inside buildings are regulated at 18–25°C independent of latitude. Hence, adults in the US modify their environments to keep TEE constant across a wide range of external ambient temperatures

Energy compensation and adiposity in humans.

Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1-3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response-energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity

Changes in body weight, adherence, and appetite during 2 years of calorie restriction: the CALERIE 2 randomized clinical trial

Background/objectives: The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE) study showed that individuals who are nonobese were able to undergo significant calorie restriction (CR), yet the time course changes in adherence, weight, and appetite are unknown. This analysis aimed to investigate the time course changes in adherence, body weight, and appetite during the CALERIE study. Subjects/methods: Overall, 143 participants (body mass index: 21.9–28.0 kg/m2) were randomized to a CR group that aimed to achieve 25% CR for 2 years. Throughout the intervention, body weight was measured, and appetite was assessed through visual analogue scales. Algorithms were utilized with body weight measurements to calculate adherence percentile score. Participants targeted an adherence percentile score of 50, though being between 80 (lowest acceptable adherence) and 10 (highest acceptable adherence) was adequate. Polynomial regression analyses were used to assess time course changes. Results: Polynomials indicated that adherence percentile score increased above 50 after approximately week 20, although adherence remained acceptable (adherence percentile score less than 80) (R2 = 0.89; P &lt; 0.001). Weight loss occurred until approximately week 60 and then plateaued (R2 ≥ 0.92; P &lt; 0.001). Hunger and thirst increased (R2 ≥ 0.30; P &lt; 0.001), but the total increase in scale scores were &lt;10 mm throughout the intervention. Conclusions: In individuals who are nonobese, adherence to 25% CR declines after 20 weeks, but 2 years of CR that stimulates a meaningful reduction in weight, promotes aging-related benefits and negligibly affects appetite is viable

Leptin and insulin responses to a four day energy deficit diet in men with different weight history.

OBJECTIVE: To assess the leptin responses to a 4-day energy-restricted diet in men with different weight history; high retrospective weight gain was expected to be associated with a small decline in leptin. DESIGN: Changes in fasting leptin and insulin were measured during a 4-day controlled intervention, in which men with high retrospective weight gain and men who had stable weight consumed 35% of their estimated energy needs. SUBJECTS: A total of 44 healthy men (age: 31-52y, BMI: 22.7-39.8 kg/m(2)) were recruited from a cohort study: 22 men who had gained weight (weight change >1 kg/y) and 22 men whose weight had remained stable (weight change +/-0.3kg/y) between the first (1987-1991) and the second measurement (1993-1997) of the cohort study. The intervention study was carried out in 2001. RESULTS: After intervention changes in fasting leptin levels were similar for both groups of retrospective weight gain: -2.2 mulU/ml (95% Cl: -2.8; -1.7) and -2.4 mulU/ml (95% Cl: -3.2; -1.7) respectively (P = 0.69). Proportional changes in fasting leptin levels were different: -43.3% (95% Cl: -47.8; -38.4) in the participants whose weight had remained stable (n-22) and -35.2% (95% Cl: -42.4; -27.1) in those who had gained weight (n=22)(