The constrained model of total energy expenditure (CMTEE) and its associations with body composition and physical activity: a systematic review

<p dir="ltr">This systematic review aimed to evaluate evidence for the Constrained Model of Total Energy Expenditure (CMTEE) as well as its relationship with body composition and physical activity (PA) outcomes. Following PRISMA 2020 guidelines, the review used the PICOS tool to conduct a comprehensive search across multiple databases.<br>The studies’ designs included randomized control trials, cross-sectional, and longitudinal approaches, and examined energy expenditure, body composition, and PA outcomes in diverse populations and age-groups. Most studies were conducted in high- income countries, with a few from middle-income regions. Sample sizes varied considerably, and participants were included if they were healthy or recreationally active. There were significant sex differences in total energy expenditure (TEE) and resting energy expenditure (REE), with females generally exhibiting lower values, likely due to higher body fat. Children’s higher PA levels were positively linked to higher<br>weight and height z-scores. Moderate-intensity exercise appeared to increase TEE with notable compensatory reductions. Cold climates were associated with higher TEE and physical activity energy expenditure (PAEE). While there is substantial evidence supporting compensatory mechanisms in total energy expenditure, these mechanisms seem to depend on contextual factors including climate, baseline levels of PA, exercise intensity, and individual physiological differences. Key research questions remain, such as the evolutionary advantage of energy compensation in resource-limited environments or whether this adaptation reflects a mismatch with modern lifestyles, potentially exacerbating obesity rates. Further research is crucial to clarify these associations and inform more effective health and weight management strategies.<br><br></p>