Evolutionary physiology of fat
For any animal living under a climate with seasons, high-carb meals are the kind you find in the summer, when it's time to make fat reserves. In the winter, you won't find any such carbs, and you'll have to burn those reserves (if you have any left), or feast on the proteins and declining fat of other animals - or else starve. No wonder it's an intake of carbs, not fat, that triggers our hormonal system to store energy as fat, and lack of carbs that tells our bodies to burn that fat.
Another reason not to listen to those evil government bureaucrats who want everyone to eat even more carbs.