I was trained the same way most physicians are trained in nutrition, and I suspect the same way that most other people in the health care industry are indoctrinated. For years, I thought the equation for weight was simple. Input equals output. If your input in terms of calories are greater than your output, then you gain weight. If your output was greater than your input, you lost weight. Simple. I recited the food pyramid to my patients diligently, and suspected that most people who thought they were following the correct diet and who did not lose weight were really not as strict as they thought. If they only counted calories, they would lose weight. I was the typical 35% cards, 35% protein, 30% fat diet guy. When I started to hack my own diet and exercise, I discovered that at least for me, what I had been taught was all wrong. Now I eat at least 50% of my calories from fat, and approximately 30–35% protein, with the rest being carbs. I don’t eat bread or pasta. I eat sweet potatoes only on a leg or back workout day (large muscle groups). I have lost body fat, my waist size is less than 30 inches, and I am 56 years old (soon to be 57). Turns out there is new science validating some of this information. As we get older, the body does not like to let go of fat. You have to trick it into thinking there is lots of fat around. It really works. If you are a male in your 40’s or older, change the way you eat. Combine it with variations of high intensity interval training. You will feel better, and you will lose the body fat. I should add I suspect the situation is more complex for women.