Underweight

For people who need to gain weight — whether due to being underweight, recovering from illness, or building lean mass — specific supplements have evidence for supporting this goal. This article examines what works, the mechanisms behind each approach, and the clinical contexts where intentional weight gain is appropriate.

Gaining weight to a healthy level requires a calorie surplus and adequate protein. Several supplements have genuine clinical evidence for supporting this goal — this guide covers what works, what does not, and the evidence behind each.