Critical analysis of dual-energy x-ray absorptiometry-measured body composition changes with voluntary weight loss.
Level 4 - case-series / case-control
Uncontrolled pre-post intervention cohort study
PubMed 40033564 · doi:10.1002/oby.24255
What was done
Dual-energy x-ray absorptiometry (DXA) scans were performed before and after a 9- to 12-week macronutrient-balanced calorie-restriction diet in 140 individuals with overweight or obesity (43 men and 97 women) to evaluate changes in lean soft tissue (LST), bone mineral content (BMC), and fat-free mass (FFM).
What was found
Men and women lost a mean (SD) of 10.8% (2.2%) and 10.7% (1.6%) of baseline weight, respectively. The proportion of weight lost as LST was significantly greater in men than women (mean [SD], 0.33 [0.11] vs. 0.25 [0.11], p < 0.001). BMC paradoxically increased, leading to a significantly smaller reduction in FFM compared to LST in men (-3.87 [1.73] kg vs. -3.92 [1.74] kg, p < 0.001) and women (-2.22 [1.18] kg vs. -2.24 [1.18] kg, p < 0.001). Body composition changes tracked as predicted a priori from baseline body composition and weight loss magnitude.
Why it matters
This study provides reference data showing that lean mass loss during caloric restriction is predictable and higher in males, establishing a baseline to benchmark body composition changes from novel anti-obesity medications.
Limits
The study lacked an active comparator or non-dieting control group. The follow-up duration was limited to 9–12 weeks without post-diet maintenance data. The paradoxical BMC increase likely reflects DXA measurement or soft tissue hydration artifacts rather than biological bone accretion.
Cited by
- supports When losing weight without resistance training, 25% to 30% of the lost weight comes from muscle mass.