Tip: Eating Crap For 2 Weeks Won't Affect You

A new study shows the surprising effects of eating nothing but McDonald's food.

There are few things more annoying than going out to eat with a "fitness person." First of all, you have to put up with their furrowed, gopher-face brow as they struggle to find something on the menu that won't, if they're male, blur their ab definition, or if their female, cause them to spontaneously sprout dreaded "arm vaginas."

Then there's the embarrassment/drama you have to endure as they grill the waiter, with the ruthlessness of a Nuremburg prosecutor, on the exact ingredients and style of preparation the chef will use in preparing their chosen dish.

Phooey. It's enough to make you want to hang out solely with happy fat people.

Maybe you're one of these orthorexic fitness people. If you are, I offer you this new study out of the University of Quebec. It suggests that dietary pratfalls, even big-time ones lasting two weeks and comprised of nothing but meals from McDonald's, have little negative effect on your health or body composition as long as you keep on exercising.

What They Did

The scientists found 15 young, physically active and healthy men to eat nothing but McDonald's food for two weeks. For breakfast they had Egg McMuffins or Sausage McMuffins with hash browns and a fruit drink or coffee.

For lunch and dinner they had either Quarter Pounders with cheese, Big Macs, or a McChicken, along with medium fries and a soft drink (non-diet). They were also allowed a daily muffin as a snack, depending on whether they were still hungry.

If you break those meals down nutritionally, you're looking at about 3500 calories, 400 grams of carbohydrate, 150 grams of fat, and 4700 mg. of sodium a day.

During that same two-week garbage fest, though, the men performed daily half-hour interval training sessions on a treadmill. They'd sprint for one minute at 90% of VO2max and then they'd walk for a minute. They repeated this one-minute sprint, one-minute walk cycle 15 times for a total of 30 minutes.

The researchers also assessed the following heath parameters before, during, and after the two-week experiment:

  • Energy expenditure
  • Body composition (as determined by DEXA)
  • Cardiometabolic profile (including lipids, hepatic enzymes, glucose, insulin, glycated hemoglobin, blood pressure, and hsCRP)
  • Maximal oxygen consumption

What They Found

Two week's of eating food that would cause the average fitness person to suffer self-loathing, paranoia, deep depression, and delusions that their previously finely-tuned body was irrevocably damaged had negligible effects on the 15 study participants.

Their cardiometabolic profile didn't budge. They didn't gain weight. In fact, they experienced improvements in body composition, estimated V02max, fasting glucose, and hsCRP levels (a marker of inflammation).

The only "bad" thing that happened was that their HDL cholesterol dropped (generally speaking, you want HDL to be high, or higher), but even so, their triglycerides/HDL cholesterol ratio remained the same (a good thing).

What This Means to You

Granted, this study has its problems. For one, it was short, so it's foolhardy to assume that this kind of diet, regardless of exercise activity, wouldn't eventually cause some harm.

Second, the sample size (15) was small. Lastly, there wasn't a control group, but the scientists felt that it wasn't ethical to muck up the health of a group of poor bastards with McDonald's food just for the sake of a study.

However, the study does help refute the popular notion that fast or "bad" food consumption is unhealthy, irrespective of physical activity. And it sure as hell refutes the notion that a single meal is going to affect your health in any measureable way, as long as you're doing some sort of exercise.

Granted, it'd be nice to see a similar experiment using weightlifters who used HIIT, CrossFit, or high-volume training, but it's probably safe to extrapolate from the findings of the current experiment and guess that the results would be somewhat similar.


  1. Christian Duval, Marc-Antoine Rouillier, Rémi Rabasa-Lhoret, and Antony D. Karelis. "High Intensity Exercise: Can It Protect You from A Fast Food Diet?" Nutrients 2017, 9(9).