Bone Marrow Adipose Tissue in Relation to Bone and Energy Metabolism in Obesity and Type 2 Diabetes Mellitus

This interventional study is part of a broader research project entitled "Bone Marrow Adipose Tissue in Relation to Bone and Energy Metabolism in Obesity and Type 2 Diabetes Mellitus." The broader project includes both a cross-sectional study evaluating bone marrow adipose tissue and bone marrow mesenchymal stem cells in people with different metabolic and bone disorders and the present dietary intervention study. The interventional study investigates whether caloric restriction changes bone marrow adipose tissue, bone health, whole-body metabolism, and the molecular and cellular characteristics of bone marrow mesenchymal stem cells in obese non-diabetic premenopausal women. A group of lean healthy premenopausal women will serve as a comparison group. Participants in the intervention group will undergo an eight-week formula-based very-low-calorie diet using Cambridge Weight Plan products, providing approximately 2.5-3.35 MJ (600-800 kcal) per day, followed by a dietary weight-maintenance phase. Participants will receive nutritional counselling, and dietary adherence, body weight, physical activity, and clinical status will be monitored during scheduled study visits. Clinical and laboratory assessments will be conducted at baseline and after 2, 6, and 12 months. Assessments will include magnetic resonance imaging and proton magnetic resonance spectroscopy of the lumbar spine to measure the amount and lipid composition of vertebral bone marrow adipose tissue. Bone mineral density and body composition will be measured using dual-energy X-ray absorptiometry, with particular attention to bone mineral density at the total hip and femoral neck. Additional measurements will include body weight, waist and hip circumference, body composition, physical activity, and fasting blood tests evaluating bone turnover, glucose and lipid metabolism, inflammatory markers, hormones, and adipokines. Bone marrow aspirates and abdominal subcutaneous adipose tissue biopsies will be obtai