bulking

/B AH1 L K IH0 NG/
verb
  1. 1

    To appear or seem to be, as to bulk or extent.

  2. 2

    To grow in size; to swell or expand.

  3. 3

    To gain body mass by means of diet, exercise, etc.

  4. 4

    To put or hold in bulk.

  5. 5

    To add bulk to, to bulk out.

noun
  1. 1

    A period of intentional weight gain.

Source: https://en.wiktionary.org/wiki/bulk, https://en.wiktionary.org/wiki/bulking