A Thai omelette is not a French omelette. The eggs are beaten with fish sauce and a splash of lime, then poured into a wok of oil so hot the edges puff and go brown. That is what makes it good, and it is also why two eggs at 150 calories become an omelette of about 220: the puffed edges hold oil. The Department of Health figure of 500 for the plate with pork reflects that, and hdmall lists a plain khao kai jeow at 445.
For 40 baht this is a decent protein plate. Two eggs and 20g of minced pork give you about 18g of protein, and with the rice it reaches 22g. The problem is the ratio: 220g of rice is 290 calories, more than the omelette, and it disappears under sriracha in about 4 minutes. Ask for kai song (two eggs) and khao noi (less rice) and you flip the ratio to more protein than starch.
Toppings are cheap here, calorie wise. Prik nam pla is fish sauce, chili and lime at about 5 calories a spoon. Sriracha is about 15 calories a tablespoon. The one that adds up is when a stall drops a second omelette on for 10 baht: that is another 220 calories, and a two omelette plate is over 700. Kai jeow with crab meat (kai jeow poo) at a seafood restaurant is around 550 as a plate.