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COLO, Iowa - A teacher in Colo, Iowa, decided to eat only at McDonald’s for 90 days to see what it would do to his health.

The result turned out to be a good lesson for him and his students.

Which picture of this man was taken after he had eaten nothing but McDonald’s for 90 days?

"The average Joe would say the guy on the right,” science teacher John Cisna said. “I can eat any food at McDonald's I want as long as I'm smart for the rest of the day with what I balance it out with."

That was the theory Cisna laid out for three of his students at Colo-Nesco high school this past fall.

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.

Cisna approached the owner of the local McDonald's franchise and the owner was so interested to see what the results would be that he agreed to provide those 90 days of meals to Cisna at no charge.

Cisna's students used McDonald’s online nutritional information to construct daily meals for their teacher, making sure to follow the nutritional limitations he had set.

"A typical breakfast would be two egg white delights, a bowl of their maple oatmeal and a 1 percent milk,” Cisna said.

A salad for lunch would be followed by more traditional value meal at dinner.

"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.

"The point behind this documentary is we all have choices,” he said. “It's not McDonald's that makes us fat it's our choices."