Do vitamins cause weight gain?

Vitamins and minerals themselves do not directly cause weight gain. They have very few or no calories. However, some people take supplements to support appetite or overall health when recovering from illness or when they were under-eating; in those cases, better nutrition might support a return to a healthier weight, which could mean weight gain for someone who was underweight.

Certain supplements marketed for “weight gain” (e.g. weight-gainer shakes) are high in calories from protein and carbs—it’s the extra calories, not the vitamins, that lead to weight change. If you are concerned about weight or supplement use, a healthcare provider or dietitian can help. This is educational only; not medical advice.