gaining weight

Gaining weight describes the process of becoming heavier, typically through increased body mass from fat, muscle, or fluid retention.

The phrase most often refers to gradual change over time rather than momentary fluctuation: I've been gaining weight since I started the new medication.

While often discussed negatively in diet culture, gaining weight can be a deliberate goal for athletes building muscle or people recovering from illness.

Someone might also speak of an idea or movement gaining weight, meaning it's becoming more substantial or influential.