That's too simple. Some foods digest better than others. I can eat the same calories from potato chips or a lentil dish but my digestion and later on weight change will be very different.
>Some foods digest better than others. I can eat the same calories from potato chips a lentil dish but my digestion and laster on weight change will be very different.
The food that exits your body without being digested falls into the "calories out" category. "Calories in calories out" does indeed represent a simple thermodynamic truth, although unfortunately the "calories out" component can be rather difficult to determine in practice.
That way makes sense but I don't think the people who use that phrase mean it that way. Usually they seem to say "a calorie is a calorie no matter where it comes from".
While no individual person may deliberately do this, the gestalt does a motte & bailey with this, where "calories in = calories out" means that people are wrong to think about how different calories affect the body differently and interact with all the feedback loops in the body and dieting is just a matter of applying willpower harder and eating less, until you challenge it, at which point it's suddenly just a tautological thermodynamic truth that apparently is being thrown into the discussion for basically no reason and with no particular purpose in mind.
It really needs to just be retired. At its best its an unhelpful tautological statement, at its worst, inflammatory and thought-terminating. Not much reason to keep dragging it in to every diet discussion.
I once tried to look up on google scholar what difference different digestibility made, and if I remember correctly with respect to fiber (the main kind of thing that reduces digestibility) you have to eat like twice the recommended amount of fiber just to reduce the total calories by like a 100. It was something like 80g of fiber, which isn't something you can easily eat without restructuring your whole diet. So the effect is there, but the way you explain it neglects to ask how big the effect is.
Food is much more complex than fiber vs. calories. I am not a scientist there but I observe myself and others a lot. When I eat certain foods I can eat a lot without weight gain, my digestions works, my mind works, I go to the bathroom regularly. When I eat junk food, I gain weight, I feel sluggish and I often get constipated. Unless I am very special, which I don't think I am, I assume other people experience the same thing.
There are additional factors on both the in and out side, but they all work in favor of losing weight. In other words, there is a maximum amount of energy in the food you eat, and a minimum amount of energy required for sustaining your being and physical activity. There simply is is no way around this.
That's too simple. Some foods digest better than others. I can eat the same calories from potato chips or a lentil dish but my digestion and later on weight change will be very different.