Morgan Spurlock decided to eat exclusively at McDonald's for a month to document the effects of a fast food diet on his health. He gained 11 kilograms and experienced serious liver problems as well as increased cholesterol and fat levels that doubled his risk of heart disease. His physical and mental health declined, experiencing depression, fatigue, mood swings, and a diminished sex drive. The documentary aimed to raise awareness of how widespread fast food consumption was contributing to obesity and health issues for many people.