Belgian hospitality is generous and it expresses itself primarily through food. If someone invites you to their home for dinner, there will be a lot of food, and refusing it will be noticed. If a colleague has a birthday, there will be cake in the office kitchen at 10am, and standing next to it with a coffee while not eating any will attract comments. If you go to a family dinner, there will be potatoes in some form, probably bread on the table, and possibly a waterzooi or a carbonnade flamande that you can eat around but not entirely avoid.
None of this is imaginary or exaggerated. Belgian food culture is genuinely more food-forward than a lot of other European contexts, and the social pressure is real.
The most practical approach is to be selectively honest. You don’t need to announce that you’re on keto to everyone you meet, and doing so tends to make meals more awkward, not less — someone will inevitably say “but you need carbs for energy” or start asking detailed questions right as the food arrives. A simple “I’m watching what I eat at the moment” is usually enough to explain why you’re skipping the bread. Most people will accept it and move on.
For restaurant meals in Brussels, the situation is better than it used to be. Almost every restaurant will accommodate a request to swap frites for salade or légumes. Brasseries are generally your best option — a steak or a piece of fish with vegetables is easy to order and doesn’t require special pleading. Italian restaurants are harder because pasta and pizza are the point. Asian restaurants vary — pho without noodles works reasonably well, sushi is trickier.
Office cake culture is genuinely hard to avoid entirely, and sometimes it’s not worth the social friction to try. One piece of birthday cake at a colleague’s birthday is not going to undo weeks of keto. The decision of whether to eat it or not is yours and depends on how strict you want to be. What doesn’t help is turning every birthday into a discussion of your dietary choices.
For home cooking, Belgian classics are more adaptable than they look. Stoofvlees works perfectly well without frites — serve it with celeriac mash or just eat it on its own. Moules work fine. Most fish preparations are straightforward. The bread basket that appears automatically at many Belgian restaurants is the main hazard; you can ask them not to bring it, or just ignore it, which takes about two weeks to stop being difficult.
The honest reality is that eating keto in Belgium requires more effort than in some other food cultures, and there will be situations where you either eat something off-plan or have an awkward conversation. Both are fine. Neither is catastrophic.