I can understand you being worried about your bf, but you nagging is more likely to make him defensive and deny that there is an issue. He needs to figure this one out for himself. You've said elsewhere that he's recently gone into teaching. He's not the only person to balloon after doing this. It's very stressful and demanding on the energy reserves and nothing gets you through like a large slab of something sweet. The walks sound like a fantastic idea though, as they're also likely to keep his stress levels down.