A 6-month trial just showed that a higher-fat, low-carbohydrate diet lowered circulating saturated fat compared with a higher-carbohydrate diet, even though people on the low-carb diet ate far more saturated fat. Palmitoleic acid, a marker of the liver making new fat from carbohydrates, also fell. All of this matches up with previously published data: when carbohydrate comes down, circulating saturated fat comes down with it.
That is the part the diet-heart story often misses. Much of the saturated fat in the blood is not arriving from the meal, but is being made. Cut the carbohydrates, insulin comes down, and the fat-generating signal to the liver turns down. All of this matters for insulin resistance. When circulating saturated fats in the blood come to a cell, they can be used to make ceramides--the very molecules that impair insulin signaling. Less saturated fat in circulation means less raw material for that process.[source]
