A new study came out last week, the latest in a long line of research purporting to show, for once and for all, that protein is killing you and clogging your arteries. They focus on the ability of the amino acid leucine (found in animal protein like meat, milk, eggs) to stimulate mTOR, a physiological pathway that is required for muscle protein synthesis and muscle gain. In general, mTOR is anabolic, promoting growth of tissues like muscle and bone. The authors posit that this is bad for arterial health, because it prevents mitochondrial autophagy—the process by which our mitochondria "eat themselves" and dispose of damaged or malfunctioning tissue. Without autophagy of the cells involved in arterial health, they can accumulate damage, increase inflammation, and even lead to blockages and heart attacks. There are a lot of issues with this. First, the animal model used to show that leucine increased atherosclerosis was a genetically modified mouse with deficient mitochondrial function and poor lipid metabolism. This is just about the most unhealthy mouse with the worst genetics possible. A mouse like this needs to optimize for mitochondrial autophagy because their mitochondria are so dysfunctional and create so much damaged tissue. A mouse like this is almost destined to get atherosclerosis because it has such poor genetic LDL clearance. Second, the dose they used to "impair" endothelial autophagy is the same dose that increases muscle protein synthesis and leads to strength and muscle gains. Ask yourself: Does it really make sense that eating enough protein to build lean muscle mass and extend functionality into old age is also bad for your heart health? Does it really make sense that something that can improve grip strength and bone density—tow factors consistently linked with longer, better lives—is also killing you? All this study highlights for me is the need to feast and fast. Don't have mTOR constantly jacked up all the time. Eat, and then don't eat. Eat large protein meals, but don't think you have to graze on protein all day long. Give your body a chance to down-regulate mTOR. Experience both the fed and fasted states on a regular basis. What about you, folks? Do you take anything else away from this paper? Let me know on X. | 
