Pig's blood is not the problem. Cooked blood is about 80 calories per 100g and mostly protein and iron, which surprises people. What decides dinuguan is the pork that goes in. Carinderias use a mix of kasim (shoulder), a bit of belly and offal like intestine and liver, which averages about 300 calories per 100g cooked. An 80g share of that is 250 calories. Kawaling Pinoy's belly-only recipe card lands at 857 per serving, and that is the home version with 2 pounds of belly for 6 people.
Red Ribbon and Goldilocks sell it as a takeout tub, and Red Ribbon's is listed at 255 calories per cup with 34g of protein. That is leaner than most carinderias because they use more lean meat and less fat. The Ilocano dinardaraan is the opposite: drier, fattier, often with bagnet and chicharon crumbled in, and a serving is 450 to 500.
The puto is the part everyone forgets. Dinuguan at merienda comes with 2 or 3 puto, and each small puto is about 40 calories. Three puto is 120, so dinuguan with puto is about 450. With 1 cup of rice instead it is about 590. At 50 to 70 pesos a serving it is a high protein ulam at about 22g, so the calorie return is decent if the cook did not use belly.