Zac Efron -- Jacked and Cursed! (TMZ TV)

Zac Effron was hiking with Anna Kendrick in Hawaii and showing off his buff body, which got us thinking -- how long can he possibly keep up that physique?

Yep, Zac's got the curse that strikes all jacked dudes in Hollywood. Once you have abs, you better keep 'em … or else!! It's a solid reason to go dadbod instead.