warum nehme ich trotz sport und kaloriendefizit nicht ab — which blood markers matter?

Not losing weight despite exercise and a calorie deficit is a common frustration. It's often not about willpower but underlying physiology that blood markers can reveal. Key markers include: thyroid panel (TSH, fT3, fT4) – hypothyroidism lowers metabolic rate. Cortisol (morning and possibly evening) – chronic stress can impair fat loss. Fasting insulin and HOMA-IR – insulin resistance blocks fat burning. HbA1c and fasting glucose – indicate glucose metabolism issues. Inflammatory markers like hs-CRP – chronic inflammation disrupts metabolism. Vitamin D, ferritin, and iron – deficiencies reduce energy and exercise capacity. Leptin (satiety hormone) may be elevated in obesity, indicating resistance, but is rarely tested. Also, an overly aggressive calorie deficit can lower resting metabolic rate (adaptive thermogenesis). The evidence for these markers is based on clinical practice and mechanistic reasoning, not large randomized trials. A doctor should interpret results, as multiple factors interact. Caveat: No single marker explains everything; a holistic view including sleep, stress, and diet quality is essential.