Belgian food has a reputation for being heavy, which in keto terms actually works in your favour more often than you’d expect. A lot of the classics are built around meat, fish, and cream-based sauces — the problem is usually the accompaniment rather than the dish itself.
What adapts well
Stoofvlees — beef slow-cooked in beer with thyme and bay — is the Belgian comfort food. The dish itself is fine on keto, but the traditional pairing with frites is obviously not. The solution most people land on is celeriac mash, which has a fraction of the carbs of potato and takes on butter extremely well. Cauliflower mash also works. On its own, stoofvlees is rich enough that the absence of frites doesn’t feel like a great deprivation after a few bites. The beer used in cooking — usually a Duvel or a brown ale — adds minimal carbs because most of the alcohol and sugars reduce during the long cooking time.
Waterzooi is mostly fine as-is. The Ghent chicken version is cream and vegetables with chicken pieces; unless whoever made it has added flour to the broth, you’re eating a perfectly keto dish. The fish version is the same. Worth asking about the base if you’re ordering in a restaurant, but made at home it’s one of the easiest Belgian dishes to cook on keto without any adaptation at all.
Moules are essentially a keto food. A pot of moules marinières is white wine, shallots, butter, and mussels — no meaningful carbs anywhere. The only problem is moules-frites as a format: you’re getting a side of frites alongside. Ask for a salad instead and nobody should object.
Paling in ’t groen — eel in green herb sauce — is worth trying if you haven’t. The herb sauce is parsley, sorrel, chervil, and butter. No carbs. The eel itself is rich, fatty protein. The whole dish is keto without trying to be. It’s more commonly found in Flemish restaurants and around Mechelen but you can find it in Brussels.
What doesn’t adapt
The waffle is the main casualty. A Liège waffle is pearl sugar baked into a yeast dough. A Brussels waffle is a crispy light batter. Neither has a keto version that isn’t a pale imitation, and the ones sold at markets with fresh fruit and whipped cream are almost certainly the thing you’ll miss most. There’s no good answer here.
Cramique — the sweet enriched bread with raisins — doesn’t adapt. Belgian flan and rice pudding don’t adapt. Speculoos in any form doesn’t adapt. The tarte au riz from the boulangeries in Liège doesn’t adapt.
The honest position is that Belgian pastry and baking culture is exceptional and largely incompatible with keto, and coming to terms with that early is better than spending time on recipe substitutions that don’t taste right. Eat the actual food around it, let the waffles be what they are, and move on.