What Is The Keto Flu?

By now, you've likely heard of the ketogenic diet — or keto, for short. Originally designed to treat epilepsy in children, the high fat, low-carb diet has become a popular weight loss method in recent years (via Cleveland Clinic). While data on the diet's effectiveness for weight loss is limited, some evidence suggests it may help people lose a few pounds, at least at first, according to Harvard Health Publishing. But the eating plan can come with side effects, including the dreaded "keto flu." The illness is not an actual medical diagnosis but has become a popular term for a group of symptoms, including nausea and fatigue, many people experience within the first week of starting the keto diet.

Typically consisting of 70 to 80 percent fats, 20 percent protein, and 5 to 10 percent carbohydrates, the diet forces the body to switch from burning glucose to burning ketones for energy, a process called ketosis. This results in a sped-up metabolism, decreased hunger, and increased muscle mass (via Cleveland Clinic).

Symptoms of the keto flu

While the benefits of the keto diet are countless, the initial transition into ketosis, the process of the body using fat as fuel, can be an uncomfortable period called the keto flu, according to Healthline. Common symptoms of the keto flu include nausea, vomiting, headache, dizziness, muscle soreness, cramping, stomach aches, and disruptions in sleep. You may also find yourself craving sugar as you begin the keto diet. Since everyone's experience with the keto flu is different, symptoms can range from mild to severe.

Diarrhea is a common symptom of the keto flu (via MedicalNewstoday). Given that the body goes through a change in the foods it's digesting, your gastrointestinal (GI) tract may need time to adjust to processing the new ingredients, particularly if you previously haven't eaten foods high in fat and low in carbs, which are the hallmarks of the keto diet. As your GI tract adjusts, you may experience a period of diarrhea, alongside an upset stomach and abdominal cramps. With the keto flu, you could also experience constipation. To ease the discomfort within your GI tract, it's advised that you prioritize eating fiber, drinking plenty of water and fluids, and taking probiotic supplements. Another option is to ease yourself into the diet rather than jumping all in at once to give your GI tract time to slowly adjust to the new foods.

How to feel better

During the keto flu period, be kind to your body by taking it easy (via Healthline). If you feel tired or weak, take time to rest. Because your sleep can be disrupted as your body adjusts to the keto diet, prioritize ways to calm your body by taking a warm bath before bed, establishing a set bedtime routine and waking up at the same time each morning, and reducing the amount of ambient light you're exposed to so that your body can wind down at night. Ambient light includes any beaming illumination from cell phones, tablets, computers, and televisions. The goal is to curate a dark, peaceful bedroom that can help you achieve restful sleep.

While your GI tract, stomach, and body adjust to the new eating plan, reduce the amount of caffeine you consume since caffeine is a stimulant that can both negatively interfere with sleep and further disrupt the GI tract (per Healthline). Avoiding heavy exercise, especially if you experience muscle soreness and weakness, will keep your body from becoming overworked. Engaging in strenuous activity can cause further stomach upset and fatigue during the keto flu. Instead of going to a high-intensity interval training (HIIT) class or lifting weights, try going for a walk, an easy bike ride, or doing yoga. Also, prioritize drinking plenty of water and replacing electrolytes, especially if you're experiencing diarrhea or vomiting. Foods high in potassium and magnesium may help relieve muscle cramping from the keto flu.

How long does the keto flu last?

While transitioning into ketosis, or going through the keto flu, symptoms should subside within one to two weeks, as per WebMD. Since the keto flu can appear between two and seven days after switching to the keto diet (via Harvard Health Publishing), it might be helpful to schedule your commencement of the diet for a period of time when you know that you can rest and take it easy for up to 10 days, according to WebMD.

One way to avoid the keto flu, or at least minimize the experience, is to try a staggered approach into the diet instead of diving in "cold turkey," advises Harvard Health Publishing. While the symptoms of the keto flu shouldn't be incapacitating, if they are too uncomfortable then a slower approach into the keto diet may help. Cyclical keto dieting, otherwise known as carb cycling, is the process of carb-loading one day a week (per Healthline). If you decide to go with a cyclical approach, you can stick with just one day per week and keep your favorite foods and carbs in your diet the rest of the week, or you can work your way up to adding additional days of the keto diet.

Keto flu is not ketoacidosis

As your body transitions into ketosis, you may hear the term confused with ketoacidosis. However, there is a big difference between these two medical experiences. Ketoacidosis, also known as diabetic ketoacidosis or DKA, is a serious and potentially life-threatening condition where there's an excessive buildup of acid in your blood and blood sugar levels remain too high for too long, reports WebMD. Symptoms of ketoacidosis include dry mouth and skin, excessive thirst, frequent urination, flushed face and skin, confusion, leaving your breath smelling sweet, and shortness of breath. 

Both ketosis and ketoacidosis involve ketones, which may be where part of the confusion between the two conditions stems from, says MedicalNewsToday. Symptoms shared by ketosis and ketoacidosis include fatigue, weakness, nausea, vomiting, and muscle soreness. Ketosis is considered to be generally safe for most people, so experiencing keto flu symptoms that are similar to ketoacidosis shouldn't be cause for alarm. But if you begin to experience symptoms of ketoacidosis that aren't common symptoms of ketosis, you should seek immediate medical attention.

Should you see a doctor?

Prior to beginning the keto diet, you should consult with your doctor to determine if it's the right fit for you. "Although this diet is very safe for most people, I urge caution and recommend medical supervision in people taking medications for diabetes or high blood pressure," physician, Jeff Stanley, MD, tells The Healthy. If you take any medications at all, you should periodically check in with your doctor to be certain that any symptoms you experience aren't potentially dangerous interactions with your medication. According to MedicalNewsToday, sodium-glucose cotransporter-2 (SGLT2) inhibitors and similar medications can negatively interact with the keto diet. People who have fat metabolism disorders may experience serious and potentially fatal side effects if they adhere to the keto diet, so it's paramount to consult with your doctor before trying the diet.

As you begin the keto diet, your doctor can recommend treatments for symptoms of the keto flu (via WebMD). If your symptoms of the keto flu last for more than 10 days or are especially severe, it's advised that you seek medical attention. Additionally, if at-home remedies like drinking fluids and resting don't resolve your symptoms, your doctor may advise assessing for nutritional deficiencies or other causes of your symptoms that may not be caused by ketosis. Since the keto diet can raise your cholesterol, it's advised that you check in with your doctor to monitor cholesterol and fat levels as you continue with the keto diet (per MedicalNewsToday).