According to the British Journal of Nutrition, it really does matter where the calories come from.
Researchers from Papworth Hospital in Cambridge, UK, compared the effects of the two nutritionally similar breakfasts on a group of volunteers. The only real difference between the meals was that one contained about 6 grams of fat and the other contained 28 grams. Total calories, however, were about the same.
While most results were similar, the high fat meal led to higher serum glucose -- and more insulin release. And that leads to a greater waist-to-hip ratio. A greater waist-to-hip ratio leads to an increased risk of blood clots, which can cause heart attacks and strokes.