MR-detected changes in liver fat, abdominal fat, and vertebral bone marrow fat after a four-week calorie restriction in obese women

Purpose: To determine changes in the bone marrow fat fraction (BMFF) in obesity after dietary intervention in comparison with changes in abdominal fat, liver fat, and serum lipids.

Materials and methods: Twenty obese (BMI 34.92 ± 3.8 kg/m(2) ) women participated in a 4-week dietary intervention of 800 kcal/d plus additional vegetables. They underwent anthropometric and blood value measurements before and after the intervention. Abdominal 3T MRI was performed to measure changes in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volume and single-voxel magnetic resonance spectroscopy (MRS) to measure fat content changes in the liver and L5 vertebral body.

Results: The greatest relative change after dietary intervention was found in the liver (-40.3%), followed by VAT volume (-15.1%), serum lipids (-12.6 to -14.5%), and SAT volume (-8.5%). There were no statistically significant changes in BMFF after dietary intervention (P = 0.39), but absolute changes in the BMFF were positively associated with SAT volume (r = 0.489) and negatively associated with nonadipose tissue volume (r = -0.493) before dietary intervention.

Conclusion: Bone marrow behaves differently compared to SAT volume, VAT volume, liver fat, and serum lipids after a 4-week dietary intervention in obesity and BMFF changes depend on abdominal tissue volumes before intervention.