Changes in resting metabolic rate and body composition due to intragastric balloon therapy

Background: Intragastric balloon (IGB) insertion leads to dietary restriction; however, its neurohormonal actions were also described. Resting metabolic rate (RMR) adjusted for body mass (RMR/mass) seems to increase after bariatric interventions, whereas it generally decreases after caloric restriction-based therapies. However, no studies have evaluated the changes in body composition and RMR over IGB treatment.

Objective: To evaluate the relationships between changes in body composition, RMR, RMR/mass, and RMR adjusted for fat-free mass (FFM) (RMR/FFM) over IGB treatment lasting 6 months.

Setting: Single-center observational study.

Methods: Twenty-one morbidly obese patients treated with IGB (143 ± 20 kg, body mass index [BMI] = 49.5 ± 7.3, 98% ± 29% percent excess weight, 43.6 ± 12.6 yr) were enrolled. Changes in body composition, RMR, RMR/mass, and RMR/FFM were evaluated between 1 month before IGB insertion (time point 1 [TP1]) and 3 months thereafter (TP2). Fourteen patients were also assessed 1 month after IGB removal (TP3).

Results: There was a 9.5% reduction in weight, a 9.4% reduction in BMI, and 19.1% decrease in percent excess weight at TP2 (n = 21; P < .001); a further 6.5% reduction in weight and BMI and a 13.1% drop in percent excess weight (n = 14, P < .001) at TP3. They were accompanied by a 5.4% reduction in FFM between TP1 and TP2 (n = 21, P < .001). Compared with pretreatment values, at TP2 RMR was 12.5% lower (P < .001) but did not change thereafter. RMR/mass increased 12.4% between TP2 and TP3 (n = 14, P = .02) but on average did not change between TP1 and TP3. The results in the smaller cohort (n = 14) between TP1 and TP2 were consistent with results obtained for the entire cohort. Similar findings were obtained for RMR/FFM. The larger increases in RMR/mass between TP1 and TP3 were associated with more weight loss, larger drop in BMI, and more loss of excess weight (r < -.55, P < .03).

Conclusion: This is the first study to evaluate the relationship between changes in body composition and RMR over IGB treatment. IGB therapy leads to both fat and fat-free mass reductions and RMR decreases. More weight reduction is associated with larger increases in RMR/mass.