His hypothesis doesn’t bother me because I came to the same conclusions some years ago. I stopped listening to my doctors and stopped eating the low-fat diet they recommended. Within a week of going on a version of a low-carb diet, my supposedly incurable autoimmune disease began to subside. Within two weeks the symptoms disappeared and they have never returned.
I struggled for years following the advice of physicians. The only thing they ever did was subject me to inhuman testing and prescribe steroids that made me feel lousy. At one point I was so sick I was unable to work regularly for close to a year. When they finally offered to cut out offending body parts I ran from them and took matters into my own hands. Soon thereafter I started a high fat low carbohydrate diet and it probably saved my life. It for sure drastically improved my quality of life and overall health.
Same with me. I’m about the only one in my family that has not gotten diabetes and I believe it is because of my diet. My digestive system doesn’t like a lot of soft carbs so I never ate them a lot. Same with fats; I figure humanity survived eating animal fats for centuries, and they are at least not man-made, so nothing wrong with them in moderation.