580 calories for a bowl of Mee Bandung Muar is honestly reasonable, bro. You're getting 28g of protein from the prawns, beef, and egg combined, decent carbs from the yellow noodles, and a gravy that tastes like it should be way worse than it is. The thick dried shrimp and tomato gravy clocks in at around 120 calories for 200ml, which is manageable. What pushes this dish up is the yellow noodles at 250 calories for 180g, they're the biggest single chunk. Fair warning though: these numbers are a ballpark estimate. Hard nutrition data for Mee Bandung Muar specifically is thin on the ground, so treat 580 as a solid working figure, not a lab result.
What actually changes the maths is how generous the stall is with the gravy and whether they finish the bowl with a splash of oil. Some places ladle on 250-300ml of gravy instead of 200ml, that alone can add another 60-80 calories. Ordering the version with double prawns and extra beef brings you to around 680 calories, still fine if that's your main meal of the day. If you swap the yellow noodles for bihun you drop to roughly 490 calories because rice vermicelli is a bit lighter. The egg is basically free at 75 calories, so no reason to skip it, you want that protein.