Comparing regular fat and low fat food
The hypothesis that most people will be able to differentiate between the taste of regular fat and low fat food, is proven to be true for most of the food samples tested.
Many people prefer to buy and consume low fat food even though it is more expensive because they believe it is healthier and will help them overcome weight problems. However, these foods are normally loaded with sugar and furthermore, we tend to eat more of it simply because we think that it is lower in fat content!
This science fair project may be repeated, this time, with a bigger group of people to do the sampling.
Modify the science project experiment, having the participants choose the food that tastes better.
The Truth behind Fat Free or Low Fat Food Which No One Has Ever Told You - http://munfitnessblog.com/the-truth-behind-fat-free-or-low-fat-food-which-no-one-has-ever-told-you/
Do low fat foods really taste different - http://lowfatcooking.about.com/od/lowfatbasics/a/lowfattaste.htm
Basic safety requirements