warum nehme ich zu trotz kaloriendefizit — when to see a doctor?

The question of why one gains weight despite a calorie deficit is nuanced. Physiologically, a true calorie deficit (energy intake < expenditure) must lead to weight loss over time. However, many factors can mask or counteract this: 1) Inaccurate tracking (underestimated portions, liquid calories, cooking oils), 2) Water retention (high sodium, carbohydrate refeeding, menstrual cycle, inflammation), 3) Metabolic adaptation (the body lowers resting energy expenditure during prolonged deficits), 4) Medications (antidepressants, corticosteroids, beta-blockers), or 5) Underlying medical conditions such as hypothyroidism, polycystic ovary syndrome (PCOS), insulin resistance, or Cushing's syndrome. Genetic variants, e.g., in the BDNF gene (rs6265), may modestly influence appetite regulation and energy balance, but evidence is moderate and not diagnostic. When to see a doctor? Seek medical evaluation if you have a documented, consistent calorie deficit over several weeks with no weight loss or actual gain, especially if accompanied by fatigue, cold intolerance, hair loss, menstrual irregularities, or mood changes. A primary care physician can perform initial labs (TSH, fasting glucose, CRP). If hormonal issues are suspected, referral to an endocrinologist is appropriate. Note: brief plateaus are normal; the body may need time to adjust.