Can DNA Stoffwechseltest help with fatigue?

A DNA metabolism test is not evidence-based for fatigue. Fatigue has many causes (sleep deprivation, stress, iron deficiency, thyroid issues, infections, etc.) that such a test does not address. The offered gene variants (e.g., APO2, ACTN3) have at most small effects on weight or muscle type, but no proven utility for diagnosing or treating fatigue. IgG food intolerance tests are also unvalidated. Instead, a medical workup (CBC, TSH, ferritin, vitamin D) and lifestyle optimization are recommended. The evidence is mostly marketing, not clinical.