- If you’re on the ketogenic diet you’re at risk of developing keto flu in the first month of starting the diet.
- Keto flu symptoms, like headache, fatigue, and nausea, typically last one to two weeks.
- You can try and avoid keto flu by staying hydrated and getting enough electrolytes.
- This article was medically reviewed by Melissa Rifkin, MS, RD, CDN, owner of Melissa Rifkin Nutrition LLC.
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Studies have shown the ketogenic diet to be an effective diet for weight loss short-term. But within the first month of starting the diet, you may experience what’s called keto flu. Keto flu symptoms include headache, brain fog, fatigue, irritability, nausea, difficulty sleeping, diarrhea, back pain, insomnia, and constipation.
It’s unclear how common keto flu is, but according to Amy Miskimon Goss, an assistant professor of nutrition sciences at the University of Alabama at Birmingham, making sure you’re getting the right types of minerals can help curb the uncomfortable side effects of a low-carb diet. Here’s what you need to know about why you may get keto flu and how you can avoid it.
What causes keto flu
The hallmark of the ketogenic diet is increasing the amount of fat you consume while cutting carbohydrates to almost nothing. When following a keto diet, a person should aim to get around 60% of their calories from fat and 5% to 10% from carbohydrates. That’s about 20 to 50 grams of carbs a day. For reference, a single banana has around 27 grams of carbs.
Starving the body of carbohydrates puts the body in a state called ketosis, in which the body metabolizes fat instead of carbohydrates, for energy. During ketosis, the liver produces keto acids, also known as ketones. Keto acids are the body’s reaction to starvation. The acids trigger fat cells to release fat so it can be used for energy when sugar and carbs are scarce.
The kidneys can process small amounts of keto acids without adverse side effects, but large amounts of the acids, like what may occur under a strict keto diet, can make you feel sick.
Moreover, keto flu is also a consequence of unproperly balanced salt levels in the body, says Goss. This happens because when the body enters ketosis, the kidneys get rid of more salt than they normally would, throwing the body’s electrolytes — a group of minerals that includes sodium, magnesium, and potassium, among others — out of whack.
How long does keto flu last
While symptoms of keto flu usually only last one to two weeks, they can stick around for months after starting the diet.
Over time, consistently elevated levels of ketones in the body may cause adrenal stress, kidney stones, and bone loss, and, the acidic nature of ketones circulating through the blood could have a variety of other negative effects on organ functions.
That’s why, as a rule of thumb, experts do not recommend following a non-medical keto diet for more than 6 to 12 months.
How to avoid keto flu
Get enough electrolytes. “A well-formulated ketogenic diet should contain enough electrolytes and intracellular minerals [like potassium, magnesium, phosphorus, iron, and zinc] to avoid keto flu,” says Goss. When your body enters ketosis, your electrolytes can easily become unbalanced. And that risk is even greater when you’re actively restricting food and calories. You can help maintain a balanced diet by eating foods like leafy greens, broccoli, cashews, avocados, almonds, and cheese. There are also many low carb electrolyte supplements available to complement dietary sources.
Consume more sodium. Low-carb diets reduce the amount of insulin your body produces, which increases the amount of salt you excrete and can cause symptoms like nausea, headaches, and fatigue. To avoid this, Goss recommends increasing how much sodium you eat while on the keto diet. However, it’s important to note that if you’re taking medications for hypertension or congestive heart failure, that you consult your doctor before even trying the keto diet. US Dietary Guidelines recommend no more than 2,300 milligrams of daily salt intake for the average healthy adult.
Stay hydrated. Electrolyte balance and water balance in the body are closely linked. And since water is stored with carbohydrates, cutting carbs can dehydrate you. Therefore, make sure to drink plenty of water because it can help flush keto acids from your body and ease side effects. The CDC notes that there’s no recommendation for how much plain water you should drink per day. However, the last time expert advice was offered on the matter was in 2004 by the National Academies of Sciences, Engineering, and Medicine, which recommends 15.5 cups of fluids per day for men and 11.5 cups for women. This can include plain water and water from food and other drinks.