Just one fast food meal can lower your brain power

A lot of us have loosened our healthy eating habits (and our belts) during this pandemic.

With all the stress, uncertainty and monotonous days spent hunkered down at home, we’ve allowed ourselves more indulgences than we usually would — burgers, fries, chips, cookies, pretty much anything salty, sweet or fatty. But it turns out, even a little bit of junk food has a swift and serious impact on your brain’s ability to function.

I’m not saying you shouldn’t enjoy some comfort food during this crazy time. Just make sure you time these meals right. Don’t eat them before a big Zoom meeting with your boss. Or before you have to help your ninth-grader with her algebra homework. Or before you compete in an online sudoku competition. Why?

Because new research shows that your ability to focus plummets almost immediately after indulging in junk food.

Fatty fast food can lead to murky mental functioning

A recent study from Ohio State University shows that a meal high in saturated fat (like the kind you’d get in a fast-food drive-thru) messes with mental performance and focus.

The study included 51 women who took a baseline test to assess their concentration and mental performance at the start of the study. Researchers then asked them to eat a meal that was high in either saturated fat or unsaturated fat. The meal included eggs, biscuits, turkey sausage and gravy. The gravy contained 60 grams of fat, which, for one meal, came from a palmitic acid-based oil high in saturated fat — and in the other meal, contained sunflower oil which is high in unsaturated fat. The meal was designed to mimic something you’d get from Burger King or McDonald’s.

Now, clearly neither meal is super healthy. But researchers wanted to see the difference saturated fat and unsaturated fat had on the brain. And the saturated fat was clearly much worse…

Five hours after eating the meal, the women were asked to complete the same test they’d taken earlier. One to four weeks later, they were asked to return to the lab to do the whole process again, except this time they got the opposite meal — women who had the saturated fat meal the first time got the unsaturated fat meal the second time, and vice versa.

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Can you guess which meal led to worse test results?

The meal filled with saturated fat, of course. After eating the meal high in saturated fat, women on average performed 11 percent worse on the attention portion of test.

Researchers also looked for evidence of leaky gut in these women. They tested blood samples for something called endotoxemia, toxins that travel from the intestines into the bloodstream when the gut barrier is compromised. They found that women with signs of leaky gut had even worse concentration. They had more erratic response times and struggled to sustain their attention during a 10-minute test.

Why would one fatty meal have such a swift impact on the brain?

Researchers didn’t delve into the “whys” in this study, but there’s been plenty of past research that shows food high in saturated fat can increase inflammation in the body and the brain. There’s also evidence that fatty acids can cross the blood-brain barrier.

Foods that help you focus

The last thing you need right now is a brain that’s not doing its job. We’re all going through a lot — adapting to working from home, homeschooling kids, trying our best not to freak out over being stuck at home all the time and trying our best not to freak out over the crazy virus that’s taken our country hostage.

So, it might be a good idea to cut your brain a break and feed it foods that help it perform better. That may mean easing up on indulgences a bit (the quarantine food party was bound to end eventually) and start embracing foods that are known for their ability to help you concentrate, be creative, be productive and feel good. Here are a few brain-healthy foods you can start savoring ASAP:

  • Blueberries
  • Oatmeal
  • Dark chocolate
  • Salmon
  • Green tea
  • Beets
  • Bananas
  • Spinach
  • Eggs
  • Walnuts
  • White beans
  • Pumpkin seeds
  • Avocados
  • Leafy greens
  • Yogurt
  • Peppermint tea

Editor’s note: Everyone ages differently—proof that what happens to your health is not completely a result of what’s imprinted on your genes. What’s the difference? How you live, love and eat, for starters. Lifestyle factors are driving disease down and they can also help you maintain a vibrant brain with age. For a preview of Nature’s Secrets for an Active, Healthy Mind at Any Ageclick here!


  1. Our ability to focus may falter after eating one meal high in saturated fat — MedicalXpress.
  2. Afternoon distraction: a high-saturated-fat meal and endotoxemia impact postmeal attention in a randomized crossover trial— The American Journal of Clinical Nutrition.
  3. 10 Foods That Boost Concentration — Health.
  4. 12 Foods to Help You Focus — The Chopra Center.
  5. Brain Foods That Help You Concentrate — WebMD.


Jenny Smiechowski

By Jenny Smiechowski

Jenny Smiechowski is a Chicago-based freelance writer who specializes in health, nutrition and the environment. Her work has appeared in online and print publications like Chicagoland Gardening magazine, Organic Lifestyle Magazine, BetterLife Magazine, TheFix.com, Hybridcars.com and Seedstock.com.