Keto Flu: How to Get Rid of It, Symptoms and How Long It Lasts
You cut the bread, swapped pasta for zucchini and stocked up on eggs. Then, a few days into keto, you wake up groggy, headachy and craving anything sweet. Welcome to what people call the "keto flu." The good news: it is common, it is usually temporary, and there are simple, practical ways to ease it. This guide explains how to get rid of keto flu, what causes it, how long it tends to last and how to make your next low-carb start smoother.
What is keto flu?
"Keto flu" is the informal name for a group of flu-like symptoms some people notice in the first days or weeks of a very low-carb ketogenic diet. Despite the name, it is not the real flu and it is not contagious. Cleveland Clinic describes it as a sign that your body is adapting to a new way of eating, and notes that there is no clear explanation for why some people get it and others do not (Cleveland Clinic).
On a ketogenic diet, carbohydrates are usually kept under about 50 grams a day, and once stored glucose is used up the liver starts turning fat into ketones for fuel (Harvard T.H. Chan School of Public Health). That switch is a big change, and for some people the transition is a bit bumpy. If you want to understand ketones themselves, read our guide What Is BHB?
Keto flu symptoms to watch for
The first scientific look at keto flu came in 2020, when researchers analyzed 448 posts from 300 users across 43 online forums (Bostock et al., Frontiers in Nutrition, 2020). The most commonly described symptoms were:
- General "flu-like" feelings
- Headache
- Fatigue and low energy
- Nausea and stomach discomfort
- Dizziness or feeling faint
- Brain fog
Cleveland Clinic adds muscle cramps, irritability, feeling "hangry," trouble falling asleep and constipation or diarrhea to the list. Keep in mind the 2020 study was based on self-reports, not clinical testing, so it shows what people commonly experience rather than proving a cause.
What causes keto flu?
Scientists have not pinned down one single cause, but a few factors are widely discussed:
- Water loss. Stored carbohydrate (glycogen) is held in the body with water. As glycogen runs down in the first days of keto, you lose water too, which can leave you feeling drained and thirsty.
- Electrolyte shifts. Along with water, you can lose sodium and other minerals, and cutting out fruit, starchy vegetables and grains may lower your intake of potassium and magnesium.
- Adapting to a new fuel. Your body is used to running mostly on glucose. Shifting toward fat and ketones takes time.
- Big, sudden changes. Eating very differently overnight, often with fewer calories, can affect energy, mood and sleep.
How long does keto flu last?
For most people, it is short. Cleveland Clinic says symptoms can last as little as two days or as long as a month, and typically about one to two weeks. In the 2020 forum study, reports peaked in the first week and dwindled after about four weeks. Everyone is different, so if symptoms are severe or do not improve, check in with your doctor.
How to get rid of keto flu: 7 practical steps
These are the most commonly recommended, low-risk ways to feel better while your body adjusts:
- Drink more water. Because you shed water early on, aim to sip steadily through the day. Plain water or sugar-free electrolyte drinks are good choices.
- Replace sodium. Increasing sodium was the single most popular remedy in the forum study, often by salting food a little more or sipping broth. If you have high blood pressure, heart or kidney issues, ask your doctor before adding salt.
- Eat potassium-rich keto foods. Avocado, leafy greens, salmon, mushrooms and nuts all fit a low-carb plan. The NIH Office of Dietary Supplements lists leafy greens and many other whole foods as good potassium sources.
- Get enough magnesium. Nuts, seeds and leafy green vegetables are good food sources, according to the NIH Office of Dietary Supplements.
- Eat enough fat and protein. Under-eating can make fatigue and cravings worse. Build meals around eggs, fish, meat, olive oil, avocado and non-starchy vegetables.
- Prioritize sleep and go easy on exercise. Cleveland Clinic suggests avoiding vigorous workouts until fatigue and cramps pass. Gentle walks and an earlier bedtime are your friends.
- Cut carbs gradually next time. Lowering carbs step by step over a week or two, rather than all at once, may make the transition easier.
Keto flu electrolytes: where to find them in food
| Electrolyte | Why it matters | Keto-friendly sources |
|---|---|---|
| Sodium | Helps your body balance fluids | Broth, a pinch of salt on meals, pickles, olives |
| Potassium | Works with sodium; supports normal muscle function | Avocado, spinach, salmon, mushrooms |
| Magnesium | Helps turn food into energy; supports muscles and nerves | Pumpkin seeds, almonds, leafy greens, dark chocolate (85%+) |
Keto flu remedies people often ask about
Electrolyte drinks, bone broth and magnesium supplements are popular. If you consider a mineral supplement, choose a sugar-free option, follow the label, and talk to your doctor first if you take medication or have kidney problems. Cleveland Clinic notes that some medicines, such as those for blood pressure and diabetes, can make symptoms worse, which is why medical advice matters before starting keto.
When to see a doctor
Keto flu is usually mild, but do not push through symptoms that feel serious. Contact a healthcare professional if you have a racing or irregular heartbeat, fainting, severe vomiting or diarrhea, confusion, or symptoms that keep getting worse. Anyone with diabetes, kidney, heart or liver conditions, who takes prescription medication, or who is pregnant or nursing should speak with a doctor before starting a ketogenic diet.
Key takeaways
- Keto flu is a set of temporary flu-like symptoms some people feel when starting keto. It is not the real flu.
- Common symptoms include headache, fatigue, nausea, dizziness, brain fog and muscle cramps.
- It usually lasts a few days to two weeks, and reports tend to fade within about a month.
- Water, sodium, potassium, magnesium, enough food, good sleep and gentle exercise are the go-to fixes.
- Easing into low-carb gradually may help you avoid it, and anyone with a health condition should talk to a doctor first.
Frequently asked questions about keto flu
How do you get rid of keto flu fast?
Drink more water, add a little salt or sip broth, eat potassium- and magnesium-rich keto foods, eat enough fat and protein, and rest. These steps target the water and electrolyte losses common in the first days of keto.
How long does keto flu last?
Usually one to two weeks. Cleveland Clinic says it can range from about two days to a month. See a doctor if symptoms are severe or not improving.
Does everyone get keto flu?
No. Many people never notice it, while others feel mild to severe symptoms. It is not clear why some people are more affected than others.
Does keto flu mean I am in ketosis?
Not necessarily. The symptoms often appear while your body is transitioning to burning more fat, but they are not a reliable test. A blood, breath or urine ketone meter is the only way to measure ketones.
Can I prevent keto flu?
You may lower your chances by reducing carbs gradually, staying hydrated, salting your food and eating plenty of low-carb vegetables, avocado, nuts and fish from day one.
Supporting your keto routine at Vita Hot Deals
Food, water and rest come first when you are adjusting to keto. If you also like the idea of adding a BHB supplement to your low-carb routine, here are two popular options in our store. BHB in these formulas is bound to minerals, so check the Supplement Facts panel, and remember a supplement does not replace electrolytes from food or water.
- Keto Strong Pills – a ketogenic formula with BHB ketones, 60 capsules per bottle, made in the USA. Multi-packs are in our Keto Strong collection.
- Trim Life Keto Pills – made in the USA with BHB ketones for adults following a ketogenic diet. See the full range in the Trim Life Labs Keto collection.
Not sure whether supplements are right for you? Our honest guide Do Keto Supplements Work for Weight Loss? walks through the evidence. Every order ships free anywhere in the USA, and you can choose Subscribe & Save for 10% off with monthly delivery.
The bottom line
Keto flu can make the first days of a new diet feel harder than they need to be, but it is usually short-lived. Drink up, salt your food, eat real low-carb foods rich in potassium and magnesium, sleep well and take it easy on workouts. Give your body a little time and patience, and the fog usually lifts.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.*