We might know the inner workings of the "machine" but we can control inputs (food) and measure outputs (weight). Let's say I eat 3 hamburgers per day and gain

We might know the inner workings of the "machine" but we can control inputs (food) and measure outputs (weight). Let's say I eat 3 hamburgers per day and gain ~1kg per month. If I reduce that to 2 hamburgers per day I maintain my weight. And when I reduce that to 1 hamburger per day I lose ~1kg per month. That is simple. As for how I feel while eating 1 hamburger that's another question. I can try to improve the machinery of my body by e.g exercising, eating healthier food, adjusting my macros, taking supplements, etc. So now I can eat 1.5 hamburgers per day and I feel better and still lose 1kg per month.