Impact of baseline adipose tissue characteristics on change in adipose tissue volume during a low calorie diet in people with obesity—results from the LION study

BACKGROUND/OBJECTIVES: Weight loss outcomes vary individually. MRI-based evaluation of adipose tissue (AT) might help identify AT characteristics that predict AT loss. This study assessed the impact of an 8-week low-calorie diet (LCD) on different AT depots and identified predictors of short-term AT loss using MRI in adults with obesity. METHODS: Eighty-one adults with obesity (mean BMI 34.08 ± 2.75 kg/m², mean age 46.3 ± 10.97 years, 49 females) underwent baseline abdominal–pelvic MRI and anthropometry, followed by a post-LCD examination. Visceral and subcutaneous AT (VAT, SAT) volumes and AT fat fraction (PDFF) were extracted. Apparent lipid volumes (PDFF × volume) were calculated. SAT and VAT volumes were subdivided into equidistant thirds along the craniocaudal axis and normalized by segmentation length. Statistical tests compared baseline vs follow-up, sex differences, and depot effects; correlations and multiple regression identified predictors of AT loss. RESULTS: After LCD, participants lost 11.61 ± 3.07 kg (p < 0.01) with significant reductions in all MRI-based AT parameters (p < 0.01). Absolute SAT loss exceeded VAT loss, while relative apparent lipid loss was higher in VAT (both p < 0.01). The largest SAT and VAT reductions occurred in the lower abdominopelvic third. The strongest predictor for most AT and apparent lipid losses was normalized baseline SAT volume in the lower abdominopelvic third, with smaller volumes favoring greater AT loss (p < 0.01 for SAT and VAT loss and SAT apparent lipid volume loss). CONCLUSIONS: An 8-week LCD primarily reduces lower abdominopelvic SAT and VAT. Lower abdominopelvic SAT volume may serve as a predictor of short-term AT loss in people with obesity.