I think it's the next raw chapter that shows them at the BBQ and Jiwon talks about being one of those" unlucky people that gets fat from drinking water" and how he has to diet (he has some flashbacks to salads, weight training and doing stereotypical disordered behaviour like watching mukbangs of people eating the food he avoids for himself). So apparently his weight is something he is concerned about. In the scene it would have been a good opportunity for DG to then understand that Jiwon has his own issues and he isn't this perfect idol that DG thinks he is, but no DG just seems to internalise any future issues Jiwon has and thinks he is the one to blame rather than realising that Jiwon has his own troubles and insecurities.

I love how the artist has shown us a glimpse of Jiwon hitting the gym in this chapter. I always wonder how he's that...meaty. This chapter has that sweet-sweet detail to it :3