In 2003, documentarian Morgan Spurlock had an idea — he would eat nothing but McDonald’s for a month. This idea eventually became the Academy-Award-nominated documentary Super Size Me.

The film has since become a staple in health classes and a go-to for anyone looking for proof of our unhealthy society. The results of his experiment were drastic: Over a month, he gained 24.5 pounds, liver damage, increased cholesterol, doubled his risk of heart disease, depression, exhaustion, mood swings, and addiction to fast food.

But there is one problem with Spurlock’s results: No one seems to be able to repeat them. And in some cases, people have actually lost weight on fast-food diets.

The most recent example of these diets is that of John Cisna, a high-school science teacher from Ankeny, Iowa. Over 90 days of eating only McDonald’s, Cisna lost 37 pounds and lowered his cholesterol. Unlike Spurlock, Cisna balanced his meals by making sure he was getting all the nutrients he needed, but if you think Cisna was only eating salads for 90 days, you are wrong.

In reference to his diet, Cisna told KCCI in Des Moines, “I had the Big Macs, I had quarter-pounders with cheese, I had sundaes, I had ice-cream cones.” Cisna also walked for 45 minutes a day.

Against all conventional logic, Cisna lost 37 pounds with 90 days of McDonald’s. In comparison, it took Spurlock more than a year to lose the 24.5 pounds he gained from Super Size Me on a detox diet, which itself became the basis of the diet book The Great American Detox Diet by his then-girlfriend, Alex Jamieson. 

If you would like to buy this book it is available on Amazon or you could lose weight faster by doing what Cisna did: Eat balanced meals and exercise (even if it’s just walking).

If you are worried that Cisna’s experiment was too different to debunk Spurlock’s documentary, why not try another documentarian. Tom Naughton made the film Fat Head after he saw Super Size Me because, as he put it,  “… the premise and the rather large gaps in logic annoyed me so much, I decided I needed to create a reply.”

Naughton found that with a similar 30-day McDonald’s diet and taking walks six nights a week instead of his usual three, he lost 12 pounds.

So what’s the truth about eating McDonalds? Clearly, it’s closer to Cisna’s experience than Spurlock’s. The latter, in making his film, did not seek to inform you on how to live a healthy life; he was more interested in scaring you into joining his side of the debate.

The only evidence I need about the consequences of McDonald’s came from the Linköping University, Sweden. Under lab conditions, seven students in their early 20s tried to replicate the conditions of Super Size Me. No exercise was allowed; the students were even given free bus passes so that they wouldn’t have to walk to class. 

The results were surprising. While all the students gained some weight and felt more lethargic than normal, cholesterol hardly changed, and their livers adapted to the diets after the third week. They found that our bodies are more adaptable than we give them credit for.

The point is this: Don’t get your health information from hacks who make documentaries or diet books, and don’t rely on people who have clear agendas to give you accurate information. With even moderate exercise a few times a week and reasonable restraint, cultural boogeymen such as fast food can be bested.