Nasi Kukus is basically steamed rice served with a piece of heavily spiced, deep-fried chicken (ayam goreng berempah), sambal, and a small pile of sides. It sounds simple but that one piece of fried chicken is pulling 300 calories on its own because it is coated in rempah paste and deep-fried. The rice and sambal are pretty tame by comparison. At 700 calories for a full plate with decent protein at 36g, it is not a disaster of a meal, honestly. If you were 128kg and eating two of these plates, yes, that is a problem. But one plate fits into a sensible day without much drama. Fair warning though: calorie data for nasi kukus is thin and the numbers here are a ballpark estimate based on component weights. Different stalls use different amounts of oil and rempah, so treat 700 kcal as a reasonable middle ground, not a lab-certified figure.
The single biggest lever is the gravy. If you go kuah banjir style, where the uncle floods your rice with curry gravy, you are looking at around 1,100 calories instead of 700. That extra ladle of curry adds close to 400 kcal in one move. Ordering a second piece of ayam goreng berempah bumps you straight to 980 calories. If you want to eat lighter, skip the ikan bilis (saves you roughly 70 calories and a bit of fat from the frying), ask for less sambal, and stick to one piece of chicken. The steamed rice portion is actually quite reasonable at 220g for 285 kcal, so the rice is not your enemy here. It is the oil in the chicken and any add-on gravy that pushes the number up fast.