At first I was like "Wait, how at the start of chapter 1 does the princess look super fit while the protagonist still look the same? Shouldn't he have made some progress?"
Then I realized that she was only 22 kg (48 lbs) over her target, so even if both of them lost 22 kg (48 lbs), he'd still be at 104 kg (229 lbs) compared to his 58 kg (128 lbs) target weight... which wouldn't necessarily look that different.
Still feels harsh for him, though... In the same time that she went from obese to super fit, he went from obese to slightly less obese