Fast food is often filled with ingredients such as soya, salt, cheese or mayonnaise and is often deep fried, which adds a lot of extra calories without adding any additional nutrition. Given the high amount of calories, it will take a significant amount of exercise to burn off the calories you take in. For example, it would take 7 hours of exercise to burn off the calories in a large Coke, fries and a Big Mac from McDonalds. Consuming this high level of calories without burning them off can lead to additional health issues.