pack on

pack on (third-person singular simple present packs on, present participle packing on, simple past and past participle packed on)

1. (transitive, informal) To add (fat, muscle, etc.) so as to increase mass or bulk.
   • 2006, Joel Marion, Men's Fitness, Dec/Jan, p. 102:

     Most strength coaches agree that to gain an inch on your arms, you have to pack on at least 10 pounds of body mass.

   • 2010, Margaret Munro, "Dad's eating habits weigh heavily on offspring: study," Vancouver Sun, 21 Oct. (Canada) (retrieved 13 Nov 2010):

     The nine males packed on so much fat their weight increased to more than 700 grams.

• Used especially in the contexts of health and bodybuilding.

• pack on the pounds