Ketosis is the "mecca" of the ketogenic diet. It's the reason you've given up bread and pasta and all those other delicious foods. A few telltale signs of ketosis — not all of them pleasant — can let you know you've hit the mark.
What Is Ketosis?
Ketosis is a metabolic state in which your body burns fat for energy. In a normal diet, carbohydrates are broken down into glucose to be used as the main source of energy. In a keto diet, carbohydrate intake is so low that the body has to use fat instead. The breakdown of fatty acids produces ketone bodies, which most cells can use to generate energy in the absence of carbohydrates.
According to Dr. Marcelo Campos, a lecturer at Harvard Medical School and clinical assistant professor at Tufts School of Medicine, this process occurs two to four days after reducing carbohydrate intake low enough. The requirements and timing of ketosis depend on the individual.
The Atkins ketosis diet involves consuming no more than 20 grams of carbs per day. If you are carefully following the diet, you should enter ketosis quite quickly. If you are eating more than 20 grams of carbs, you may still enter ketosis.
A keto diet typically includes between 20 and 50 grams of carbs per day, according to the authors of an article published online in StatPearls in January 2019. How few carbs you need to be in ketosis depends on the individual. Protein intake also plays a role, as too much protein can prevent ketosis.
Don't confuse ketosis with ketoacidosis. Although they are related, the latter is a much more serious condition that happens when someone with diabetes has very high blood sugar and ketones build up to dangerous levels. According to an article in the International Journal of Environmental Research and Public Health in February 2014, ketone levels in ketosis top out at 7 or 8 mmol/L (126 to 144 mg/dL in U.S. units), while diabetic ketoacidosis levels may exceed 20 mmol/L (360 mg/dL).
Read more: 16 Diet-Friendly Healthful Carbs
Signs of Ketosis
The most accurate way to know whether you are in ketosis is via urine testing. Test strips you can buy online and use at home measure the presence and concentration of ketone bodies in your urine. These are inexpensive and good to keep on hand for daily testing.
There are several other ways to potentially gauge whether you are in ketosis, although they aren't as accurate as test strips. Ketosis side effects are very noticeable, and most people experience them in the beginning.
However, it's not easy to tell whether they are merely symptoms of reducing your carb intake below normal levels or whether they are due to actually being in ketosis. Even reducing carbs to moderate levels above 50 grams — not enough to promote ketosis, but still considered low carb — could also have similar side effects.
The most common ketosis symptoms include:
- Reduced exercise tolerance
- Constipation or diarrhea
- Muscle cramps
- Bad breath
- Skin rash
This cluster of symptoms is sometimes referred to as the "keto flu." It's not a medical diagnosis or an actual virus. According to Campos, the cause of these symptoms isn't known. First and foremost, taking away your body's main source of energy that it has relied on for decades can be a big shock to the system.
Additionally, many people, especially those who ate a lot of processed carbohydrates, will experience a sort of withdrawal. Although it might surprise you, refined carbohydrates can have characteristics of hard drugs that make them addictive, according to authors of an article published in the journal Plos One in February 2015.
Campos surmises that other factors may be involved, such as detoxification or an immunologic reaction. He also says that these ketosis side effects could occur with any big dietary change, so you can't be sure that they are signs that you are definitely in ketosis.
Help for Ketosis Symptoms
Whether or not you are actually in ketosis when you're experiencing some or all of the symptoms above, you're most likely not feeling very well. In fact, you're probably thinking about grabbing a few slices of bread and some butter right now. But Campos urges you not to give up if you are committed to the diet — or at least seeing if it works for you. The good news is that ketosis side effects usually dissipate once the body adapts to the change.
Although you can't "cure" the keto flu, you can take a few steps to make yourself feel better — or at least, not worse:
Stay hydrated: Very low-carb diets can cause you to lose fluids. This is a major reason many people see noticeable weight loss in the first week. Unfortunately, it's just water weight. But this loss of water can result in dehydration if you're not careful.
Dehydration can exacerbate the fatigue and dizziness you already may be feeling, so be sure to drink plenty of fluids. According to the Mayo Clinic, men need 15.5 cups of fluids each day and women need 11.5. Some of this comes from the foods you eat, but about 80 percent should come from drinking water and other unsweetened drinks.
Replace electrolytes: Fluid loss can cause excess losses of important electrolyte minerals, including sodium, magnesium, calcium and potassium. Deficiencies of these minerals can cause irregular heartbeat, muscle cramps and spasms, weakness and lethargy, fatigue, nausea and vomiting — a lot of the same symptoms of the keto diet itself. There's no need to take an electrolyte supplement; just be sure to get enough electrolyte-rich foods including leafy greens, fish, nuts and salt.
Get plenty of sleep: This is not the time to skimp on shut-eye. Although you may be having trouble sleeping, do your best to get eight hours of sleep each night.
Take it slowly: You may want to get into ketosis ASAP, but if it's causing you a lot of distress and affecting your daily functioning, you need to reconsider how to get there. Campos suggests starting again, but this time more slowly. Gradually reduce your carb intake and up your fat consumption over several days or weeks. This will give your body the opportunity to become accustomed to the shift over time, and the ketosis symptoms may be much less bothersome.
- StatPearls: "Ketogenic Diet"
- Harvard Health Publishing: "Ketogenic Diet: Is the Ultimate Low-Carb Diet Good for You?"
- Atkins: "Atkins 20®: A Low Carb Ketogenic Diet"
- Mayo Clinic: "Diabetic Ketoacidosis"
- International Journal of Environmental Research and Public Health: "Ketogenic Diet for Obesity: Friend or Foe?"
- MedlinePlus: "Ketones in Urine"
- Mayo Clinic: "Low-Carb Diet: Can It Help You Lose Weight?"
- Plos One: "Which Foods May Be Addictive? The Roles of Processing, Fat Content, and Glycemic Load"
- StatPearls: "Low Carbohydrate Diet"
- Mayo Clinic: "Water: How Much Should You Drink Every Day?"
- UNM Comprehensive Cancer Center: "Electrolyte Imbalance"