Brisket noodles are one of the better deals on a Hong Kong noodle menu if you care about protein. CFS measured 50g of protein in a 640g bowl, which is close to two chicken breasts, for 550 calories. The brisket is the reason: about 120g of slow cooked beef per bowl. The trade off is fat, at 17g with 6g of it saturated, because brisket is a fatty cut and the broth is skimmed less than you would like.
The noodle choice moves the number more than people expect. Thin egg noodles land at 550 and thick at 520, but a bowl of ho fun with the same brisket is 670 because flat rice noodles are heavier and soak up more soup. Rice vermicelli sits at 610. If you always order 牛腩河 out of habit, switching to 牛腩麵 saves about 120 calories a bowl with the same amount of beef on top.
The soup is the sodium problem, not the calorie problem. CFS found 3,100mg of sodium in a bowl of brisket with thin noodles, which is one and a half days of the 2,000mg WHO limit in a single lunch. Most of it is in the broth, so the trick is simple: eat the noodles and the meat, leave at least half the soup. The famous brisket shops also serve a curry version (咖喱牛腩) and that adds around 100 calories from the coconut and oil in the sauce.