It is generally accepted that weight management is a matter of simple math: to lose weight, you need to consume fewer calories than you burn each day. But leading scientists are increasingly questioning this belief as carbohydrate, fat, and protein calories appear to have different effects on weight gain.

A study published in The Journal of the American Medical Association, reports that those who ate a low carbohydrate and high fat/protein diet kept more weight off than those who chose a high carbohydrate diet.  All participants in the study consumed a similar number of calories but the types of calories consumed varied. 

Three potential reasons for the varying effects of calories types are presented in this Scientific American article.  First, different foods take different amounts of energy to digest.  “Proteins can require ten to twenty times as much heat-energy to digest as fats”, for example.  Second, foods differ in how readily they are absorbed.  Simple carbohydrates are absorbed quickly by the small intestine while more complex molecules are broken down by microbes in the colon, with the microbes consuming a portion of the calories.  Third, “some foods require our immune system to get involved during digestion in order to deal with potential pathogens.”  Meats, particularly lightly cooked ones, present microbes that the body must investigate, even if they do not turn out to be harmful. 

So, is a calorie a calorie?  The emerging research suggests that the answer is no and that we should be placing a greater emphasis on the type of calories we consume.

Food Babe has done an investigation, The Weight Loss Secret The Food Industry Doesn’t Want You To Know, speaking directly to this topic.