Weight Loss and Adipose Tissue Metabolism During Conservative Treatment of Obesity

Adipose Tissue Metabolism in Obesity and Diet-Induced Weight Loss: A Prospective Observational Study of Body Weight, Fat Distribution, and Tissue-Specific Metabolic Adaptations

This prospective observational study investigates weight loss and metabolic changes in adults with obesity undergoing standard clinical diet-induced lifestyle treatment and counseling. Participants follow a very-low-calorie diet followed by a conventional weight loss diet in addition to lifestyle counseling and are followed for 12 months. The study examines weight loss as the primary outcome and characterizes changes in body composition, fat distribution, glucose metabolism, inflammation, and adipose tissue biology as secondary outcomes.

Obesity is associated with metabolic complications including insulin resistance, fatty liver disease, dyslipidaemia, and systemic inflammation. Weight loss can improve these complications, yet individuals vary widely in weight loss, fat distribution and metabolic response. Subcutaneous adipose tissue dysfunction, including impaired mitochondrial biogenesis and increased inflammation, is thought to play a central role.

This prospective observational study follows adults with obesity undergoing standard-of-care diet and lifestyle treatment at Helsinki University Central Hospital, Helsinki, Finland. The intervention consists of a very-low-calorie diet for approximately 10 weeks, followed by gradual transition to a conventional weight loss diet and multidisciplinary clinical follow-up.

Assessments are performed at baseline, 6 months, and 12 months and include anthropometry, body composition (BIA, DXA), fasting blood samples, and oral glucose tolerance testing. Subcutaneous adipose tissue biopsies are obtained from four anatomical depots (gluteal, abdominal, breast, and upper arm) for molecular, mitochondrial, epigenetic, and histological analyses.

The primary outcome is diet-induced weight loss over 12 months. Secondary outcomes include changes in fat distribution, insulin sensitivity, lipid profile, inflammation, mitochondrial measures in adipose tissue, and depot-specific adipose tissue characteristics.

Inclusion Criteria:

• Age ≥18 years
• BMI ≥28 kg/m²
• Seeking treatment for obesity at Helsinki University Central Hospital or affiliated units

Exclusion Criteria:

• Pregnancy or lactation
• Current smoking
• Anemia (Hb <130 g/L in men; <120 g/L in women)
• Severe comorbid disease or condition judged by investigator to compromise safety
• Contraindications to MRI (e.g., metal implants, claustrophobia)