[topaz0]

If you read the article, you'll notice that this fact is acknowledged there. The issue is that energy in and energy out are not so simple as the Nutrition Facts make them seem. For example, different amounts of energy are consumed in the process of digesting various foods, and some energy is excreted undigested, in a way that depends on the food and the person. Similar complexities apply on the "calories out" side, where a large fraction of your energy expenditure is not directly controlled by your choice of activities like exercise. Ultimately there is some arithmetic of calories in minus calories out, but it is not captured by the simplistic calculations that are normally done.

[naasking]

> The issue is that energy in and energy out are not so simple as the Nutrition Facts make them seem.

"Calories in calories out" is a rule of thumb that is as true as "what goes up must come down". Which is to say that it's not true on the extreme margins, but it's true for virtually all of the cases anyone is likely to encounter in their lives.

[fredophile]

I think this problem gets overstated by the anti CICO crowd. Most people will habitually make and eat the same, relatively small, collection of meals. If you're eating the same foods and nothing outside has changed (travel, stress, sleep, exercise, etc) then the difference between what the nutrition facts show and what your body gets out of the food should be pretty consistent.