Anata is a Japanese restaurant on Boulevard Anspach, a few minutes from the Bourse. It does sushi, noodle dishes, donburi rice bowls and yakitori, the full range of a casual Japanese lunch spot. For keto purposes, about half the menu is immediately useful and the other half can be adapted or ignored.
The sashimi is the obvious starting point. Raw fish sliced and served without rice is keto by definition, whether salmon, tuna, yellowtail or whatever is on offer. A sashimi plate as a starter or a main is a complete keto-friendly meal with nothing to negotiate.
Yakitori, the grilled skewers, are the other strong option. Chicken thigh, chicken with spring onion, chicken with cheese, pork belly, beef: all grilled, all low-carb, all good. The cheese yakitori sounds slightly unusual if you are not familiar with it, but it works, because the cheese melts into the chicken during grilling and the result is better than it has any right to be. Order several skewers and you have a proper lunch.
What to skip and what to adapt
The noodle dishes are off. With ramen, udon and soba the noodles are the point, and there is no useful substitution.
Donburi, the rice bowls, are worth ordering if you ask for them without the rice or with very little. With gyudon, oyakodon or karaage don the protein and sauce on top are fine; it is the bed of rice underneath that adds up. Some places will do this without complaint, others will look confused. Worth asking.
Sushi rolls are borderline, since the rice in a standard maki or nigiri is not enormous but adds up across a full lunch order. Sashimi is the cleaner option. Temaki hand rolls can sometimes be ordered with less rice.
The miso soup that comes with set lunches has minimal carbs and is worth drinking, and it is also useful for electrolytes, which matters if you are in the early stages of keto.
The restaurant
It is a genuinely Japanese place; the reviews mention actual Japanese staff and regulars, which usually means the food is made by people who eat it themselves rather than approximating it for a Western market. The portions are generous for the price range and the lunch sets are good value.
It sits at Boulevard Anspach 74 in central Brussels, close enough to the Bourse metro stop to walk easily from most of the centre. It gets busy at peak lunch hour, so it is worth going slightly early or slightly late if you want a table without waiting.
A genuinely Japanese lunch spot near the centre of Brussels that works for keto, at a price point that does not require explaining to your employer, is a more useful thing to know than it might seem on a normal working day.