I recently had a fun conversation with someone about calories, in food specifically. It's pretty common to count calories, or at least to acknowledge those numbers that grocery stores now put on the front of packages (instead of hidden on the back). They must be very important, right?
A calorie is not a calorie
At the end of the day, to measure how good or bad food is by the measure of calories is pretty mis-guided. I won't bore you with too many scientific details, because it's pretty simple. Calorie is a measurement of energy. But the calorie count (the energy) in food only tells us how much energy it contains, not what kind of energy.
Our body store and use different kinds of energy (e.g. fat, protein and carbs) in different ways. For example, the body is designed to store fat as a reserve, and carbohydrates is kept readily available by the body to burn and use at any time.
Imagine if you would compare two similar persons that both eat 3000 kcal per day and move/exercise the same amount. Person A only eats deep-fried meat and egg mayonnaise and person B only eats whole foods, vegetables and fruit. I think everyone would agree that the health of person A and B would develop very differently, despite consuming the same amount of calories.
All calories aren't equal. The studies referenced in this video explains it all in more detail.
It's not about "energy in and out"
Another popular thing is to believe that "calories consumed vs. calories expended" needs to be net negative to reach certain health benefits, like losing weight. This is also known as caloric restriction. But as per the studies referenced above, those benefits has less to do with caloric restriction and more to do with the reduced intake of animal protein.
What if you already eat no animal protein? Just eat more whole foods and less processed foods. Quite literally, count the colours and not the calories!