The phrase "to gain weight" means to increase in body mass or size due to an accumulation of fat, muscle, bone, and other tissues. This can happen when a person consumes more calories than they burn through physical activity or metabolism.
Sentences with «one's gain weight»
You will not gain any weight back if you stop the program. (colonzone.org)
I'm eating well but can't gain weight back on low carb diet. (drcate.com)
For example, the process of gaining weight of newborns can be slowed down because they often lose 7 percent of their weight after birth. (shrewdmommy.com)