A high-fat diet also trains your body to burn even more fat during exercise, even at high intensities. Fat is released faster and in greater amounts from your storage adipose tissue and transported more quickly into your muscles and mitochondria. Your muscles also store more energy as fat and use this fat-based fuel more efficiently and quickly. Even more interestingly, a high-fat diet can cause a shift in the gene expression that codes for specific proteins that increase fat metabolism – and create very similar adaptations to exercise itself. So the mere act of shifting primary fuel intake from carbohydrates to fat begins to make you more “fit”, even if you’re not exercising.