Glucose regulation during weight loss under dissociation of negative energy balance and changed body composition: preliminary data from an ongoing randomized controlled trial

Introduction: Weight loss is linked to metabolic benefits like improved glucose regulation. However, the impact of negative energy balance and changed body composition have not been investigated separately.

Methods: 51 overweight/obese post-menopausal women were enrolled. The control group (CG: n = 26) remained weight stable over a period of 4 months. The intervention group (IG: n = 25) underwent a very low calorie (liquid and regular) diet (˜800 kcal/d) as well as nutrition counseling for 3 months (M3) and was subsequently kept weight stable for another month (M4). Phenotyping included assessment of body composition and an oral glucose tolerance test at baseline (M0), M3 and M4. Glucose area under the curves (AUC) were calculated using the trapezoid method.

Results: The IG lost on average 12.4 kg of body weight (92.9 ± 12,3 vs. 79.7 ± 11.0 kg, p < 0.001) and remained weight stable between M3 and M4 (79.4 ± 11.4 kg, p = ns). The CG remained weight stable between M0 and M4 (95.3 ± 13.7 vs. 93.4 ± 10.4 kg, p = ns). The IG showed a decrease in body fat (FM) and fat free mass (FFM) between M0 and M3 (45.8 ± 8.9 vs. 34.9 ± 9.3 and 47.1 ± 5.2 vs. 44.8 ± 5.1 kg, each p < 0.001) and remained stable until M4 (33.9 ± 9.9 and 45.5 ± 5.1 kg; both p = ns). Incremental und total AUC decreased between M0 and M3 (iAUC: 11049 ± 3602 vs. 10190 ± 2822, p < 0.05; tAUC: 23738 ± 4749 vs. 22074 ± 3531, p < 0.05), however remained stable until M4 (iAUC: 10516 ± 3357, tAUC: 22451 ± 4137, both p = ns).

Conclusions: Improvement of glucose regulation during weight loss may primarily be driven by changes in body composition rather than energy balance.