The last time we saw an experiment involving someone eating only at McDonald’s for a period of time, it didn’t go so well.

You may remember Morgan Spurlock’s 2004 documentary, “Super Size Me,” which ended with the filmmaker gaining weight and complaining of all sorts of health problems after a month of eating breakfast, lunch and dinner at the fast food emporium.

A decade later, with many new options on the menu, another man is reporting much different results.

John Cisna, a high school science teacher in Colo, Iowa, says he has lost 37 pounds and lowered his cholesterol after 90 days of eating all of his meals at McDonald’s. But it wasn’t a hamburger free-for-all: Cisna followed a 2,000 calorie diet, using the daily recommended allowances for carbohydrates, proteins, sugar and fat; and he walked 45 minutes a day.

When the experiment began on Sept. 15, the 6-foot-tall teacher weighed 280 pounds, amounting to a body mass index (BMI) of 38, which is considered obese.

“If I had gotten any bigger, I’d probably have to avoid harpoons,” Cisna told TODAY’s Savannah Guthrie and Matt Lauer on Monday, adding that he was barely able to exercise.

Trending stories,celebrity news and all the best of TODAY. This site is protected by recaptcha

“When I started that first day, I thought I was going to die. I couldn’t even walk 45 minutes carrying that (weight.)"

Cisna, 54, let his students plan his meals and made his own documentary of the process. A sample menu showed him eating an Egg White Delight, a sausage burrito and oatmeal for breakfast. Lunch included a Southwest salad and a Fruit & Yogurt Parfait, while dinner featured a grilled chicken sandwich, a Caesar salad with grilled chicken and small fries.

Now weighing 243 pounds, Cisna considers the results of his blood tests a much bigger deal: he says his total cholesterol dropped from 249 to 170, including a 34 percent decrease in his LDL or “bad cholesterol.” He also lost four inches from his hips and seven inches from his stomach.

Registered dietician and TODAY contributor Joy Bauer cautioned most people wouldn’t be able to mimic Cisna’s outcome because when faced with a fast food menu, they’d be too tempted to order a huge hamburger rather than a small salad.

But she’s glad most fast food companies now offer lighter options and said she wasn’t surprised by Cisna’s results.

“If you lose weight and you’re overweight to begin with, normally your cholesterol, your blood sugar, your triglycerides, they will come down, too,” Bauer said.

“I think this isn’t really the McDonald’s diet, I think what John proved is that it’s not where you eat, it’s what you eat.”

Bauer pointed out Cisna’s students went out of their way to pick relatively healthy items on McDonald’s menu, though she wasn’t thrilled that Cisna often drank Diet Coke. She also discovered a “glaring red flag”: the salt he was taking in on a daily basis was more than double what’s recommended.

Cisna said he’s not a paid spokesman for McDonald’s, though local franchises donated his food. He was largely inspired to do the experiment by Spurlock’s film, which he called “irresponsible journalism” because it didn’t teach kids choice.

He plans to continue the diet until March 15, but include even more exercise in his daily routine. Bauer’s goal, meanwhile, is to show him how to eat 2,000 calories a day without any fast food.

“I'm pretty confident he would have felt even better had he done this outside of a fast food chain, by eating food picks like vegetable omelets, lentil soups, fish with broccoli and sweet potato,” Bauer said.