Efficacy of providing energy expenditure information to guide weight loss interventions in people with obesity: A randomized controlled trial

Resting energy expenditure (REE) and metabolic fuel utilization (carbohydrate or fat) proxied by respiratory quotient (RQ) from indirect calorimetry enables more precise measurement of energy needs and fat oxidation capacity. The study compared the effectiveness of providing energy expenditure information during diet and exercise weight intervention versus standard of care (SOC) on weight loss outcomes. Fifty-two participants with obesity were recruited from a specialist weight loss service, randomized 1:1 to intervention (INT) or SOC only. Participants in INT received four-weekly dietetic counselling, using biofeedback from energy expenditure data to recommend caloric restriction and physical activity goals, in addition to SOC. The primary outcome was the mean difference in weight loss between both groups after 24 weeks. Secondary outcomes include participant acceptability and tolerability using indirect calorimetry. Participants in the INT group demonstrated additional weight loss (-2.3 kg [95% CI: -3.1, -1.5]; p <.001), reduced waist circumference (-3.9 cm [95% CI: -5.48, -2.26]; p <.001), and decreased body fat percentage (-1.5% [95% CI:-2.31, -0.72], p <.001), compared to SOC, after adjusting for baseline body mass index, age, and sex. Forty-two percent (10/24) of participants in INT group achieved the minimum clinically significant threshold of 5% weight loss from baseline, compared to 8% (2/26) in the SOC group (p = .007). Participant acceptability and tolerability of indirect calorimetry were high, with mean scores of 4.5 ± 0.6 and 4.2 ± 0.7 (5-point Likert scale). The study establishes the safety and practical integration of biofeedback using indirect calorimetry promoting improved self-regulation and enhancing weight loss.