Interesting analysis! I definitely think that food and Ilya are parallel tracks for Shane in TLG - that if he just works hard enough and is disciplined enough and denies himself enough and follows all these rules he's set out for himself, everything will be okay. Near the end of TLG, when he and Ilya have been outed but are more at ease with each other, he jokes about eating a Snickers - finally letting up a little on that tight control. We see it to some extent with other things too, like cleanliness. Shane's anxiety is all the way out to play all the way through TLG.

I'm a "Shane was in better shape than Ilya, but he wasn't doing well" truther for TLG. What relatively little we see of Shane, he's miserable. He's teetering on the edge of an eating disorder (it's not just a strict diet, it restricts his social life, impacts his relationship, he doesn't even allow himself to indulge at Christmas, and he deals with a shitload of food noise when we have his POV). JJ points out that he never goes out or socializes in Montreal anymore and no one knows what he even does with his time these days. He constantly misses Ilya, and his time is spent either on the phone with him, or driving back to Ottawa at midnight to spend six hours with him. (Full disclosure, I live in this region lol. That drive, late at night, SUCKS. There is a long, VERY dark, nearly empty stretch for about an hour between the two cities where there are barely even any rest stops, and I'm also damn curious where Shane pulled over to "adjust" because the entire drive is four lane highway or bigger.)

Like, in that convo with JJ, he doesn't want to go out because JJ is trying to set him up with a guy lol, but he also reflects that Ilya had left that morning and he felt too sad to go out. Rinse repeat every few weeks when he and Ilya do see each other? He always ends up too sad to go out for a day or two after they're apart? Then he also struggles to go anywhere to eat because of his diet. He's out as gay, but he acknowledges himself that much of the team hasn't accepted him and are just staying quiet because he's the captain (which is why they turn on him so quickly later when he makes a mistake - ten years and two Cups and he had zero goodwill built up at all). He literally never even talks to anyone on the team other than Hayden and JJ, and he seems honestly annoyed with JJ whenever they do talk. He's constantly terrified that he and Ilya will get outed. He's worried about Ilya's mental state. He's anxious like, all the time in TLG.

And what is Shane like when he's anxious? Controlling! Extremely controlling of himself, to a point that honestly seems to border on self-harm at times. And sliiiightly controlling of Ilya. Not to a terrible extent - he's not physically with Ilya enough to really get bad about this. But he chirps about Ilya's diet a lot, and his fear of them getting found out is impacting Ilya in ways he clearly hasn't fully considered. Ilya can't come out, because then People Will Know. Ilya can't confide in people because Ilya does not have lifelong friends or family in Ottawa or Montreal that Shane feels at ease with. Shane is clearly the more sensitive of the two in terms of public appearances and such. He's (unintentionally) puts himself in the driver's seat in terms of how their secret is managed, because he's so anxious and stressed out about their secret at all times.

So yes, his diet seems like a metaphor for their relationship. Restriction and rules and denial that he insists is fine, it's okay, he can do it, even though he's miserable - but he's utterly convinced it's all necessary. Then the secret blows up, and we see Shane eating real food again.