The One Side Effect You Need To Watch Out For On The Keto Diet, According To Experts

by Julia Guerra

Any time you make a lifestyle change, be it subtle or significant, you can expect your body is going to react in one way or another. This is specifically true when it comes to your diet. For example, when you make the switch from carbo load to carbo-no, like you would on the keto diet, your body has to actively change where it’s sourcing its energy from. This takes a lot more effort than you might realize, and you might even end up “catching” the keto flu. The keto flu is a side effect to the keto diet, and it isn’t that uncommon for those making the transition. It also isn’t that different from that flu you might develop from sharing a drink with your best friend, or from forgetting to wash your hands before lunch hour at work, so you’re definitely going to want to know how to nurse your body back to health ASAP.

In case you aren’t tapped into the latest in trendy food regimens, let me clue you in: The keto diet, according to nutritionist and founder of Pure Change, Dr. Charles Passler, is a “low carbohydrate, high fat and moderate protein diet” wherein you essentially eliminate carbs from the bulk of your meals, therefore requiring the body to “find alternative sources of fuel," he told Elite Daily back in March. See, your body typically holds on to the glucose in carbohydrates for energy; take that away, and it's left with fat storage to use as fuel. Fat fuel and carb fuel are two very different sources of energy, so your body has to readjust itself entirely to make ends meet and keep you feeling good and energized. It’s not an easy task, and it can take some getting used to — some bodies respond quickly, and others are subject to developing what’s called the keto flu. Sounds like a blast, doesn’t it?

Yeah, it’s really not. Kristoffer Quiaoit, co-founder and CEO of keto-friendly cookie brand Nui, tells Elite Daily that if your body initially responds poorly to the keto diet, the keto flu is probably going to rear its ugly head anywhere between three to five days after you’ve started the diet. At that point, he says, your body’s starting to use fat instead of carbohydrates to create energy fuel, and it’s an adjustment period, so while it’s “learning how to function without carbs and use fatty acids effectively,” your body is actively “flushing out water and electrolytes,” he explains. In other words, your insides are a little chaotic right now, so it cues the flu symptoms as a result.

And what, you may ask, are these flu-like symptoms? They're basically the same kind of stuff you’d expect to catch during the winter months. Symptoms can “range from fever, to aches, to nausea and dizziness, to brain fog and fatigue,” Grace Derocha, registered dietitian, certified diabetes educator, and certified health coach at Blue Cross Blue Shield of Michigan, tells Elite Daily over email. And you know how viral flu-like symptoms can last up to three weeks? Derocha says the keto flu symptoms can linger as little as three days, but they can also last for as long as an entire month. Plus, Derocha adds, because you’re opting out of most whole grains, fruits, and veggies on the keto diet, it’s likely that the switch is wreaking a bit of havoc on your immune system and gastrointestinal tract. It honestly just keeps getting better and better, doesn't it?

It’s worth noting, though, that the keto flu is not an actual flu which, according to the Mayo Clinic, is a viral infection that attacks your respiratory system. And while the Centers for Disease Control and Prevention state that every year, roughly 5 to 20 percent of the American population catches the flu, there is very little research that says how many people will develop keto flu when switching to the diet, and that’s mainly because it really depends on your individual body’s response. However, according to Passler, the issue is relatively common, and again, if it happens to you, you'll typically start to notice the signs between your third and fifth day on the keto diet.

So if it’s like the flu, but it’s not the flu, how are you supposed to cope? For starters, Dr. Josh Axe, D.N.M., C.N.S., D.C., founder of Ancient Nutrition and, suggests eating an abundance of alkaline foods that are rich in nutrients, fight off inflammation, and help your body sustain a balanced pH level. Foods like green veggies, avocado, mushroom, apple cider vinegar, and green juices all work well here, Dr. Axe tells Elite Daily, adding that it’s also a wise choice to cut out caffeine as much as you can. Staying hydrated, eating foods high in fiber, and taking your vitamins (B12 especially), Axe says, should also reduce your symptoms.

As for preventing flu-like symptoms before their onset, Passler says it’s definitely possible. The first tip he offers is to start transitioning into the keto diet slowly because, if you think about it, there really is no need to rush. “Some people like to jump [right] into the keto diet,” Passler notes, because many of them are simply in a rush to reap the benefits, like enhanced energy levels, clearer skin, and lower blood pressure. However, he recommends you “take it slow if you do not want to experience the [negative] side effects of the keto diet."

On top of going into this way of eating slowly and steadily, Passler gives you the go-ahead to drink and eat a lot of good-for you foods and healthy fats to make sure you’re feeling full and energized. Of course, if you notice your flu-like symptoms aren't going away, it's best to check in with your doctor to see what exactly is causing you to feel sick, and to see whether it's time for you to switch off of this diet. After all, no diet is worth sacrificing your health for, no matter how trendy it is.