This is going to make you feel a lot better about that 20-piece McNugget meal you ate last night. A science teacher in Iowa decided to eat nothing but meals from McDonald's for three months, and he managed to lose 37 pounds in the process.

Driven by the 2004 film "Supersize Me," which ended with disastrous results, science teacher John Cisna of Ankeny, Iowa decided to put together his own experiment. “I can eat any food at McDonalds I want as long as I’m smart for the rest of the day with what I balance it out with,” he said.

Cisna limited himself to 2,000 calories a day and tried to stay as close to recommended levels of nutrients like carbohydrates, proteins and fat. So while he may eat a Big Mac for dinner, he’d have to pass on the McGriddle’s for some yogurt or oatmeal. Even so, he even let his students pick out the food he would eat. Imagine leaving your diet up to a bunch of teenagers?

Well, it worked out, Cisna told KCCI News he had lost 37 pounds, his cholesterol dropped from 249 to 170 and his low-density lipoprotein dropped from 173 to 113. He also managed to get all the meals for free from his local McDonalds. Not a bad marketing gamble for the fast-food franchise.

It doesn’t hurt that he also walked 45 minutes a day during the experiment. So diet and exercise are still the answer. Cisna told KCCI he doesn’t necessarily recommend that we all go out and pick up our three meals a day under the Golden Arches. Instead, he says, we should pay attention to our daily nutrition. “We all have choices. It’s our choices that make us fat not McDonald’s,” Cisna added.

What’s most impressive is that he was able to stomach nothing but McDonald’s for three months straight. So, unless you plan on taking a 45-minute stroll at some point tonight, that 20-piece McNugget and large Coke (and the beers we know you had) remain a poor choice.

The video segment featuring John Cisna, courtesy of KCCI News, can be viewed below.