Everyone underestimates the bao bro. It looks light and fluffy so your brain files it as a small snack. But that soft white dough is enriched flour plus sugar, and the char siew inside is glazed in a sweet, slightly oily sauce. One steamed bun is around 240 calories, and almost no one stops at one.
The baked char siew bao, the golden glazed kind, is even heavier because the top is brushed with sugar and egg wash and sometimes butter. If you are choosing, the plain steamed white bao is the lighter call. Either way, one bao is a snack with the calories of a small meal, so count it properly.