It will go back up just as fast when he sees some pizza or chicken nuggets then slurp it down with some soda. These people don't have self control no point in wasting your breath.
Music being motivation to lose weight and words like need to lose are a big clues. If he does lose the fat by some miracle it isn't going to stay that for long. In a few weeks he is gaining that back.
No he won't and this is why:
Once you've properly conditioned your body and got it to a good place of metabolic equilibrium through disciplined and diligent exercise (not missing weeks or too many days), eating that food will make you feel sick. So it's a natural feedback mechanism that you can attain to reject too much unhealthy food. However, you need to get to that conditioning first
For me, I can't drink alcohol hardly at all now without it making me feel sick. A can of soda will make me feel sick. It's because my body is now highly conditioned.