Runners care about their bodies. Most enjoy staying in shape and hearing about foods or beverages that promote a healthy body and don’t interfere with performance. However, there are a number of foods on the market that runners should stay away from at all costs because they are known for inhibiting athletic performance, decreasing energy and function, and causing negative health effects on the body. It is important for athletes to avoid certain foods and drinks and to watch out for certain ingredients because they can disrupt a runner’s performance. Some may seem obvious, but perhaps the reasons to avoid them are unknown. In this review, we take a look at the worst foods or drinks for runners to consume, as well as why you should avoid them.