What role does MTHFR play in weight loss?

MTHFR (methylenetetrahydrofolate reductase) is an enzyme involved in folate metabolism and homocysteine regulation. Variants like C677T (rs1801133) can reduce enzyme activity, potentially raising homocysteine levels. Some research suggests an indirect link to weight management through inflammation or insulin sensitivity, but the evidence is weak and inconsistent. There is no robust proof that MTHFR variants directly cause weight loss or gain, nor that they dictate a specific diet for weight loss. Any effect is small and overshadowed by lifestyle factors. Consumer DNA tests often overclaim single-gene influences. A MTHFR result alone does not warrant special weight-loss interventions. A balanced diet rich in natural folate (e.g., leafy greens) and, if indicated, medical monitoring of homocysteine are reasonable. Evidence: mechanistic/unclear.