For years, I tried to do everything but calories in, calories out. My weight basically never budged, unless it went up. I was convinced that CICO wasn’t the solution, it was all insulin and hormones. After all, I was riding an hour a day most days, so there was no way I wasn’t in a deficit. Plus, I had already lost 75 pounds on keto just a few years earlier. So it must be the insulin, right?
(Even I was ignoring the fact that many years before, I had lost 20-30 pounds eating two to three meals of white rice every day, until I gained half of it back from drinking too many sodas, unaware of their calories).
Then just a few months ago, I started weighing everything by the gram, and counting every calorie consumed and burned. I lost about 16 pounds in two or three months. It IS the calories.
That said, the idea that all calories are exactly equivalent is prima facia silly. Calories are a measure of heat released from literally burning a material with a flame. A pound of wood has something like 1,500 calories. None of them will be absorbed by the body. Sugar alcohols like xylitol have seven calories per gram, but they aren’t absorbed by the body, so they are effectively calorie free.
Even actual dietary calories aren’t equivalent. Fat has a thermic effect of something like 95%, while protein has a thermic effect of 75-80%. So a 100 calories of olive oil is basically 100 calories, but 100 calories of skinless chicken breast is really only 80 calories.
Carbs and alcohol (technically a carb, but it has more calories per gram) have thermic effects a bit lower than fat, hence why they both have a bigger effect on weight than protein.
So calories in isn’t really about calories consumed, it’s dietary calories absorbed.
Ultimately, the quality of a food boils down to its satiety per calorie. 500 calories of birthday cake makes you want another 500 calories of birthday cake. 500 calories of broccoli will make you never want to eat broccoli again.
Humans basically eat until they get a certain amount of protein, micronutrients, weight, and volume. If you pick foods with low calorie density, high protein, high fiber, high water, and high in micronutrients, you will be more satiated even with less calories. This is how body builders get to insanely low body fat percentages.
As for RMR, the effect of dieting on RMR for a few months is so small that it’s basically within the margin of error if you are sufficiently active and have a sufficient average calorie deficit. RMR is mostly a matter of lean body mass. Your RMR mostly goes down if you lose weight because you are a smaller, more efficient version of yourself.
Thank you for coming to my TED(X) talk.