Oxidizing a lot of fat lowers the NAD to NADH ratio, increases the reductive state, and inhibits pyruvate dehydrogenase.

“so if you give more fat they're basically the fatty acids to the process of beta oxidation uh they lower something known as the NAD to the nadh ratio in other words they're going to increase your reductive State they increase the amount of nadh and the energy to the nah ratio controls how well the enzyme pyruvates the hydrogenase works and that is the rate limiting enzyme assuming all everything else is healthy that's the rate limiting enzyme of the metabolism of glucose so if you have a lot of fat if you're oxidizing a lot of fat this puts a break on the metabolism of glucose”