Interindividual Variability in Metabolic Adaptation of NEAT After Weight Loss in Former Elite Athletes

Dr. Ganesh H K - MBBS, MD, DM. Consultant at the department of Endocrinologist at A.J. Hospital and Research Centre, Mangalore.

A one-year weight loss intervention in former elite athletes found no consistent drop in non-exercise physical activity (NEPA) or non-exercise activity thermogenesis (NEAT) though individual responses varied widely and remained largely unexplained.

Weight loss interventions often fall short of expectations, and this is partly blamed on poor adherence to diet and physical activity recommendations. But another possible factor is metabolic compensation, where the body responds to energy restriction by cutting back on NEPA or NEAT, quietly working against the intended calorie deficit. Researchers wanted to know whether this kind of adaptive thermogenesis (AT) shows up in NEAT after weight loss, and whether it relates to how much weight is actually lost.

A total of ninety-four former athletes (mean age 43.0 years, mean BMI 31.1 kg/m², 34.0% female) were randomized to an intervention group or a control group. The intervention group underwent a 1-year lifestyle-based weight loss program; the control group received no treatment. Physical activity was assessed using accelerometry, and NEAT was estimated via a predictive model incorporating baseline characteristics. Fat-free mass and fat mass were assessed using dual-energy x-ray absorptiometry.

No significant differences emerged in NEPA or NEAT in the intervention group after weight loss, and on average, adaptive thermogenesis wasn't detected in either group. However, the standard deviation of individual response was notably large at 12 months, suggesting that while the average person showed little change, individual results varied substantially, likely reflecting normal day-to-day fluctuation and measurement noise rather than a true compensatory pattern. No link was found between adaptive thermogenesis in NEAT and changes in body composition.

(Reference: Nunes CL, Rosa GB, Jesus F, Heymsfield SB, Minderico CS, Martins P, Sardinha LB, Silva AM. Interindividual variability in metabolic adaptation of non‐exercise activity thermogenesis after a 1‐year weight loss intervention in former elite athletes. European Journal of Sport Science. 2023 Aug;23(8):1761-70.)