Of all the nutrition myths, the calorie myth is one of the most pervasive and most damaging.

It’s the idea that calories are the most important part of the diet — that the sources of these calories don’t matter.

“A calorie is a calorie is a calorie,” they say — that it doesn’t matter whether you eat a 100 calories of candy or broccoli, they will have the same effect on your weight.

It’s true that all calories have the same amount of energy. One dietary calorie contains 4,184 Joules of energy. In that respect, a calorie is a calorie.

But when it comes to your body, things are not that simple. The human body is a highly complex biochemical system with elaborate processes that regulate energy balance.

Different foods go through different biochemical pathways, some of which are inefficient and cause energy (calories) to be lost as heat ( 1 ).

Even more important is the fact that different foods and macronutrients have a major effect on the hormones and brain centers that control hunger and eating behavior.

The foods you eat can have a huge impact on the biological processes that control when, what and how much you eat.

Here are 6 proven examples of why a calorie is not a calorie.