Most people have some history with calorie counting. Some do it to lose extra pounds, others track them to gain weight. Calories — depending on whether they come from carbs, fat, or protein — are sometimes seen as the enemy. But they shouldn’t be.

Technically speaking, a calorie is a unit that measures energy. Not that we mean to scare you, but in nutrition, what we refer to as a single calorie is actually a kilocalorie, or 1,000 calories. Numbers usually make most matters simple, but not when it comes to food. How much energy you consume from eating means next to nothing if you don’t pay attention to the other nutrients in the food.

“Foods that are higher in calories but also rich in other healthy nutrients are better for you than low-calorie foods that have nothing but sugar,” Lorraine Kearney, a registered nutrition and dietetics technician and founder of Lorraine Kearney Nutrition, said.

The process of burning calories is, unfortunately, not simple either. The basic fact that is true in all cases is that to need a calorie deficit — you have to burn more calories than you consume in a day. (These are 28 weight loss myths that pack on pounds.)

But the factors that play a key role into how exactly this is achieved vary from person to person. This is why many people who think they are doing everything right to get in shape or simply lead a healthier lifestyle are disappointed when they don’t see any improvement.

To compile a list of myths and facts about calories people should know, 24/7 Tempo consulted several healthy eating experts such as registered and certified nutritionists as well as diabetics technicians.

Click here to read about 17 things nutritionists want you to know about calories