It may sound like the dream diet free from calorie-counting, but there's more to why John Cisna, an American school teacher based in Iowa, lost weight and lowered his cholesterol by only eating fast food meals for 90 days.
He ate breakfast, lunch and dinner from a menu of McDonald's meals, and while some were at the healthier end of the spectrum - oatmeal and egg whites - he was keen to point out that he did ate cheeseburgers.
So how did he do it? The experiment, which he conducted with the help of his students, had to adhere to strict nutritional guidelines. He wasn't allowed to eat more than 2,000 calories a day, and he had to make sure he was getting the recommended amount of protein, carbohydrates and fats. He also took up walking.
In the end, he lost 37 pounds.
What the experiment ultimately proved, was not that eating McDonalds is the way to lose weight, but rather paying attention to your recommended daily amount of calories and nutrition is the key to sensible weight loss.