When overweight women after menopause eat fewer calories but don’t lose weight too fast, the weight they lose from their muscle and non-fat tissue is mostly just water going out, not actual muscle or minerals—no matter if they exercise or not.

A randomized controlled trial enrolling overweight, postmenopausal women assigned to either a moderate energy restriction diet with resistance training or moderate energy restriction alone, with no exercise control. Body composition is measured using dual-energy X-ray absorptiometry (DXA) and bioimpedance spectroscopy before and after 12 weeks to quantify changes in fat-free mass, total body water, and protein–mineral mass separately.

A metabolic ward study where overweight, postmenopausal women are admitted for 12 weeks under controlled diet and fluid intake, with daily measurements of total body water and protein–mineral mass using isotope dilution and DXA, comparing changes during moderate energy restriction with and without resistance training.

A prospective cohort study tracking overweight, postmenopausal women undergoing moderate energy restriction in a real-world setting, with serial measurements of body water and protein–mineral mass using validated methods to determine the proportion of fat-free mass loss attributable to each component.

A meta-analysis pooling individual-level data from published RCTs of moderate energy restriction in overweight, postmenopausal women, comparing changes in total body water and protein–mineral mass between sedentary and resistance-trained groups.

A small mechanistic study using stable isotopes to track protein turnover and water flux during energy restriction in overweight, postmenopausal women, to determine whether protein–mineral mass is preserved while water is lost.