John Cisna is a 55-year-old science teacher for Iowa who decided to undergo a crazy experiment on himself. Wanting "to prove the power of healthy food choices," Cisna decided to eat food strictly from a McDonald's menu for three whole months.

He even recruited three of his students to help with the experiment: they came up with a strict 2,000 calorie meal plan, which was paired with 45 minutes of walking every single day.

John Cisna immediately saw the success behind the experiment and decided to extend it for three more months. The experiment lasted a total of 180 days.

You can expect that John Cisna eventually ate every single item on the McDonald's menu throughout the experimentation period. In his documentary footage, he shared:

"I had everything. I had Quarter Pounders with Cheese, I had ice cream cones, I had sundaes... and what's really amazing that people find unbelievable is probably 95 percent of every day, I had French fries."

So, what was the secret to the experiment? John Cisna shares:

"The key to this experiment was carefully planning my choices so I met the calorie parameters each day that we had set. [...] What it really comes down to is it's not where you eat, but what you eat - and how much you eat, that really makes the difference."

Here's a breakdown of the physical and health changes that John Cisna experienced:

•  Day 1: John weighed 280 pounds. It took him for to five days into the experiment before being able to walk the full 45 minutes.
•  For the first three months, John lost 37 pounds. His cholesterol went down to 170 from 249. His triglycerides dropped down to 80 from a whopping 156. His Low-density lipoprotein (bad cholesterol) went from 170 to 113.
•  After the extended three months, Cisna increased the intensity of his exercise. He lost a total of 60 pounds.

After the experiment, McDonald's signed up John Cisna to be an official brand ambassador.