A Tale of Two All-McDonald's Diets

Depending on who is doing the eating, living off nothing but burgers and McNuggets has wildly different outcomes.

(Photo: Joe Raedle/Getty Images)

May 12, 2015· 2 MIN READ
Jason Best is a regular contributor to TakePart who has worked for Gourmet and the Natural Resources Defense Council.

Just when McDonald’s thought it may have found its very own Jared Fogle—the “Subway Guy”—to prove you can go on a steady diet of Mickey D’s and still be healthy, here comes news that eating too many Big Macs may be more like declaring war on the good bacteria in your gut.

Ever since the phenomenon of the popular documentary Super Size Me more than a decade ago, plenty of Internet memes surrounding the question of “What crazy things happen to your body when you eat a ton of McDonald’s?” have been spawned. The sheer ubiquity of the once indomitable fast-food chain swiftly made it the lumbering target for everything that’s gone wrong with how we eat, and thus, the prime culprit behind Americans’ ever-expanding waistlines and related health issues.

But last year, a high school science teacher from Iowa became a viral sensation by touting an all-McDonald’s diet that allowed him to shed more than 60 pounds in six months. It started as a class project: John Cisna challenged his students to come up with a diet consisting entirely of food from McDonald’s yet still within the federal government’s 2,000-calorie-a-day guideline for adults, and he gamely became the class guinea pig.

This week, McDonald’s confirmed that Cisna is now an “official brand ambassador” for the chain: He’s not an employee, but he gets paid for his appearances, according to ABC News.

Alas, the gods that govern the sphere of clickable headlines are fickle indeed. Just as McDonald’s moves to embrace Cisna, here come the father-son duo of Tim and Tom Spector with their own “McDonald’s diet” story—and it’s hardly the kind of PR the burger giant wants going viral.

Tim is a well-regarded professor of genetic epidemiology at King’s College London; his 23-year-old son Tom, apparently following in his dad’s footsteps, is a genetics student at Aberystwyth University. The elder Spector recruited his son for a one-man experiment: What would happen to the young man’s gut bacteria if he subsisted on nothing but McDonald’s for 10 days?

Whereas Cisna’s students devised a diet for him that took full advantage of McDonald’s more recent healthier-for-you options, such as a couple of Egg White Delight sandwiches for breakfast or a fruit parfait and salad for lunch, Tom Spector ate nothing but chicken nuggets, Big Macs, fries, and Coke.

The results? “Before I started my father’s fast-food diet, there were about 3,500 bacterial species in my gut, dominated by a type called firmicutes,” Tom told The Australian. “Once on the diet, I rapidly lost 1,300 species of bacteria, and my gut was dominated by a different group called bacteroidetes. The implication is that the McDonald’s diet killed 1,300 of my gut species.”

One man eating McDonald’s for 10 days does not make for the most convincing scientific evidence. Yet Team Spector’s headline-grabbing story does add to the growing body of research that suggests our modern, often junk-food-heavy diet may be wreaking havoc on our gut microbiome, killing off any number of the countless species of bacteria that keep our metabolism in balance. A recent study of artificial sweeteners in diet soda, for example, found that aspartame and sucralose change gut bacteria in such a manner that blood-sugar levels increase—kicking off a process that can lead to weight gain and other diet-related health problems.

Far from a microbiologist’s flourishing Garden of Eden, some research suggests that the guts of modern-day humans appear more like a patchy, weedy vacant city lot.

“What is emerging is that changes in our gut microbe community, or microbiome, are likely to be responsible for much of our obesity epidemic, and consequences like diabetes, cancer and heart disease,” Tim Spector told The Australian. “It is clear that the more diverse your diet, the more diverse your microbes and the better your health at any age.”

But just as research on the microbiome and its impacts on health is a burgeoning field, medical procedures aimed at repopulating a diseased or depleted gut with healthy bacteria are also on the rise.

It appears McDonald’s has yet to respond to the Spectors’ experiment. But like most purveyors of junk food these days, the company that once single-handedly made “supersizing” a verb has been taking a different tack. Commenting on the company’s newest brand ambassador, a McDonald’s spokeswoman told ABC News that Cisna’s story reflects “the importance of choice and balance.”