Hypertrophy isn't determined by specific reps and sets but by total accumulation of volume. You can generate hypertrophy with 1 set of 20 or 20 sets of 1 and all sorts of other crazy means in between.
When you have less food, you have less recovery, which traditionally means volume needs to be scaled down. You can do this by reducing reps, reducing sets, reducing movements performing, reducing amount of conditioning performed, etc etc. You can also reduce rest times, which impairs your ability to lift heavier weights, which means you end up with less total volume.
Also, 3x5 isn't what powerlifters do. Powerlifters (at least good ones) ALSO train with a variety of rep ranges and have periods of high accumulations of volume with lower intensity and high intensity with low volume. It is never a simple question of a certain set and rep combination equals a certain outcome.