Pork belly is the fattiest cut most people eat, and grilling does not fix that. Raw belly is about 50 percent fat. On the grill maybe a fifth of that renders out and drips away, which leaves cooked liempo around 400 calories per 100g. A 150g serving, which is one decent slab or 5 to 6 slices, is 600 calories. Kawaling Pinoy's recipe card goes even higher at 830 per serving because it counts the whole marinade.
The marinade adds less than people think. Soy sauce, calamansi, garlic and 2 tablespoons of brown sugar across 2 pounds of pork works out to maybe 20 calories per serving that actually clings to the meat. The banana ketchup glaze some stalls brush on adds another 20 to 30. The calories are in the pork, full stop.
The cheap fix nobody takes is asking for the leaner slab. Belly from closer to the ribs has more meat and less fat, and a 150g piece can be 450 calories instead of 600. At a stall the fatty pieces are the ones that look striped white. A liempo meal with rice at a carinderia runs 100 to 150 pesos and about 860 calories, which is more than a Chickenjoy meal.