This is what I've been talking about:
Science teacher loses almost 40 pounds on ‘McDonald’s diet’

...

Ninety days of Mickey D’s for breakfast, lunch and dinner but with strict daily nutritional limitations of 2,000 calories and trying to stay close to the recommended dietary allowances for nutrients like carbohydrates, proteins, fat calories and cholesterol.

...

“So this isn’t something where you say, ‘Well he went to McDonald’s and he only had the salads,’” Cisna said. “No, I had the Big Macs, the Quarter Pounders with cheese, I had sundaes, I had ice cream cones.”

During the experiment, he also started walking 45 minutes a day.

By the day 90, Cisna reports he lost 37 pounds and his cholesterol dropped from 249 to 170.

He said the moral of this lesson isn’t to eat more at McDonald’s but to pay attention to your daily nutrition and what you eat.
For the past 7 years, I've had the exact same experience. Watch your calorie intake, keep a balanced diet, and exercise.

It's not McDonald's that makes people fat. It's people's ignorance.

You also can't slim down just by avoiding McDonald's, because doing only that doesn't make you smart.