warum nehme ich trotz kaloriendefizit nicht ab — what does this mean exactly?

The question 'why am I not losing weight despite a calorie deficit' is common and multifactorial. While thermodynamics (calories in vs. out) is fundamental, the body adapts: metabolic rate can drop (adaptive thermogenesis), calorie tracking is often inaccurate, and non-exercise activity may decrease unconsciously. Hormonal issues (thyroid, cortisol, insulin resistance), poor sleep, stress, and certain medications can also hinder fat loss. Genetic variants (e.g., FADS1, PPARA, FTO) have small effects on metabolism and appetite, but no single DNA test can explain weight loss resistance. Evidence is mixed: mechanistic and observational studies exist, but robust clinical trials for personalized genetic diets are lacking. Practical steps: verify your calorie counting, consider a dietitian, check thyroid and fasting insulin, and avoid extreme deficits. Caveat: sustainable loss is 0.5–1 kg per week; faster loss often leads to muscle loss and metabolic slowdown.