If you eat fat, it goes straight to your fat cells.
Think about that for a second.
How on earth does that make sense? It's not like the molecules are going straight to your stomach/fat area of the body (hips, butt, thighs etc.). That's not how bodies function.
Watch the free documentary Fat Head. It should explain a lot.
And of course, this all may not be true for every single person on the planet. Some people really do thrive on higher fructose diets, while others gain fat.