answer:Sounds like most fast food meals, especially McDonald’s – but not limited to. You really get hungry after Chinese, but again, not limited to. The current thought is it is due to certain types of carbohydrates with a high Glycemic Index (GI). For many years, it was thought that monosodium glutamate (MSG), a commonly used ingredient in Chinese fast food, was responsible for the rapid return of hunger. However, this is no longer considered the case. Instead, many scientists now believe this is due to certain types of carbohydrates found in rice and pasta. With a high glycemic index, the body needs to produce extra insulin, thereby causing a drop in blood sugar. A short answer to that question is the fact that you ate fast-food. Fast food is almost always extremely calorie-dense, due to the high fat and sugar content that most fast foods undoubtedly have. Carbohydrates (sugars): around 4.3 calories per gram protein: around 4.1 calories per gram fats: around 9 calories per gram In short, it all adds up very fast. Fats and proteins do not effeciently provide the body with usable energy; the most easily broken down fuel source is carbohydrates. Since Carbohydrates contain about half of the calories as an equal amount of fat, you can thus have a much larger volume of carbohydrates and consume the same amount of calories. The bottom line is that natural foods (not fast-food) is going to be much less calorie-dense, and therefore give you a lot more energy, while at the same time keeping you full. (Source: the Internet)