Know your enemies The biggest nutritional villains of all are trans fat and saturated fat. Both activate a gene that causes destructive inflammation in your arteries. Try to stick to under 20 grams a day of trans fat and saturated fat combined. An average croissant has around 32 grams. A four-ounce slice of roast pork tenderloin has about four grams. Trans fats—or hydrogenated oils—found in many processed and baked foods are probably at least as bad as saturated fats, maybe even a little worse.