When I was in science today, Mr. Sawyer (my science teacher) taught me a science experiment. If you want, you can do this at home.
What you need is a piece of brown paper and some food. You put the food on the brown paper and press on it firmly, but don't squish the food. Then take the food off the paper and if the brown paper is see-through, that means it has fat in it. If it has a liquid that seems to evaporate over time, that means it doesn't have any fat in it.
I might tell you more experiments as my food studies go on in science. Because in science, Mr. Sawyer said we will be doing a lot of experiments on food.