Some additional notes:
I like to think that breakfast is Leon's favorite because it was the first thing he shared with the police officer after his parent's death... OR simply because breakfast meant that he had a valid excuse to eat something sweet (given the hc that he has a sweet tooth).
Leon’s love language being food, he’s a decent enough cook to make his favorite dishes, but I also think it would be funny if he could only make sweet things. Just the imagery of an exhausted Claire going, “No, you can’t eat sweet things for breakfast, lunch, AND dinner.” That being said, Leon never got the chance to cook food for Sherry because the normalcy never happened and they were quickly taken into custody after Claire departed.
RE4r Leon lacks fat and is mostly pure muscle. His body struggles to regulate its temperature and he often ends up with cold limbs. I think his relationship with food deteriorated during his time in military training, both because of the quality (and quantity) of food he was afforded, and due to the environment he was in. The forced conscription and the way Leon is/was treated like a tool to be honed and sharpened definitely messed up his psyche, and his tendency to value the mission above all bleeds into his relationship with food. Leon often forgets to eat during his missions. He might tell himself that he'll grab something to eat after he gets Ashley back... but once Ashley is with him, all he can think of is progressing forward. I think post-RE4r, Leon is better about eating, but between missions and the knowledge that he's contributing to the government coverups, Leon starts to deteriorate again... until the fight with Arias in New York.
I think of Leon in Vendetta choosing to drink in some bar in Colorado vs drinking alone in his room a lot, and I think of Leon hardly living in his (government-issued) apartment to the point where it's like a dusty show-room. The absence of a tangible proof of his existence in the form of a lived-in space... The bed is hardly slept in because Leon is almost always shipped off to some new mission and the kitchen cabinets are empty because even if he does have some off-time, the majority of it is spent exhausted or drinking to numb the emotions away. In a twisted way, Leon might prefer to drink outside, more than just to maintain appearances, but also because if something did happen to him, Hunnigan wouldn't be the first one to find him.
DI Leon is much healthier. He's filled out and grown even more muscle mass to the point where his old shirts don't fit anymore... Hunnigan might joke about Leon dying from clogged arteries before dying from a mission, but she's internally happy that Leon seems better than she's ever seen him. Leon's living space is more lived in now. The fridge and cabinets have food in them and Leon is trying his best to get back into cooking. He might've even gotten married (who knows?) or moved in with someone. His relationship with Sherry might've been a little shaky post-RE6 but by DI, it settled down and Sherry now comes by to eat dinner with him often (Jake might stop by...). She also visits Hunnigan's office for a Dunkin' run every once in a while. If Leon isn't drinking a large-sized Dunkin' macchiato, then it's his coffee with a concerning amount of creamer and sugar.
By RE9, Leon still has a sweet-tooth but he's probably been scolded by his doctor enough that he's at least a little cautious of it. A few DSO agents once saw him throw in a generous amount of sugar into his coffee but no one believes them because he looks so scary and gruff (plus, have you seen his car???) that no, that was probably for his handler or something.
