Well done on starting your keto journey. It has been a few days since your step towards keto and you are surely feeling enthusiastic and looking forward to its many benefits. However something feels odd. You feel irritable, tired and have a headache as well as a hard time concentrating.
Congratulations, you have what is commonly referred to as the keto flu. It’s not actually a flu and it isn’t dangerous or contagious, but it can definitely be very unpleasant.
Most people feel one or more of these symptoms in the beginning of their keto diet, especially the first week or so. Fortunately it is temporary and the effects can be greatly reduced with a simple fix. Once the keto flu subsides you will be feeling even more energetic and well disposed than you were before beginning the diet.
The keto flu
Here are the main symptoms of the keto flu:
- Difficulty focussing (“brain fog”)
- Lack of motivation
- Sugar cravings
- Muscle cramps
The cause of the keto flu
When you switch from a diet containing high amounts of carbs to a diet containing a very low carb content, you will see a drop in your body’s insulin levels. This is a healthy outcome and is exactly what we are aiming for in the keto diet. When insulin levels are very low, your liver starts converting fat into ketones, which can be readily used by most of your cells as a substitute for glucose.
However it takes the brain and some organs longer to adapt to the new source of fuel. When insulin drops in the body, it responds naturally by excreting more sodium in the urine along with water. This is the reason why you will notice you are urinating more in the first few weeks of keto.
In this effect lies one of the best side effects of the keto diet – the rapid weight loss of the first weeks. It is very rewarding to start a diet and immediately shed some kilos and feel less bloated. However, the loss of water and sodium is responsible for many of the symptoms of the keto flu.
The effects of the keto flu will be more or less pronounced depending on the individual. For some people they may be mild while for others it may impact their ability to function during the day.
However there are simple steps that can be taken to mitigate the effects of the keto flu.
The antidote to the keto flu
While the effects of the keto flu will be gone in a few days, there is no reason to suffer through the symptoms if there is a simple remedy available. Below are our tips for you to recover faster from the keto flu.
1- Drink more water and eat more salt
Since losing water and salt is responsible for most of the flu’s symptoms, the obvious answer to them is to try and replace the water and the salt lost. This often helps reduce the symptoms or even eliminate them altogether.
During the beginning of your keto diet, whenever you feel dizziness, lethargy, headaches, nausea or other symptoms, just have a glass of water with half a teaspoon of salt. This should alleviate the symptoms within 15 to 30 minutes. It is ok to do this twice a day or more as needed.
In addition, make sure you are properly hydrated, by drinking a lot of water. The bigger you are, the more water you will lose and the more water you need to drink. A good rule is to drink at least 3 litres of water per day, part of which can come from teas or coffees.
Getting enough water, sodium and other electrolytes can also help with constipation, which is another issue often faced in the early stages of the diet.
<link learn more about electrolyte supplementation on a keto diet>
2 – Eating more fat will reduce the symptoms
Usually drinking more water and having more salt resolve most of the symptoms, but if you are still feeling under the weather, try eating more fat.
We have had decades of misinformation regarding fat, partly due to early studies, which came to erroneous conclusions about the role of fat in our bodies. The dissemination of these out dated views about fat is responsible for the fat-fobia with which newcomers approach the keto diet. As medicine and nutrition advanced over the years we now understand that fat is a necessary component of our organism, and we now understand how to use fat to our advantage in becoming healthier.
When you sharply lower your ingestion of carbohydrates without increasing your consumption of fat, you will feel hungry, tired and miserable.
Make sure you have a well-balanced keto diet, which includes enough fat to make you satiated after each meal, enabling you to go longer without eating while still feeling energized. In the beginning of your diet you can increase you fat intake more until your body becomes fat-adapted (e.g. adapted at using fat as a fuel source). Once you are fat-adapted you can start cutting back on fat according to your appetite.
Check out our keto recipes for tasty meals with the fat content you need.
3- Slow down the transition into keto
Ok, you are drinking more water, eating more salt and eating more fat, but you still feel bad. At this point you have two options. The best option is to hang in there. Remember, the keto flu symptoms are only temporary. Research shows that drastically eliminating carbs from your diet is best for weight loss and metabolic issues like type-2 diabetes. The wait is well worth the benefit.
The other option is to slow down your transition into ketosis by eliminating carbs in a more gradual manner. You can start by following a more moderate low-carb diet providing 20 to 50 grams of carbs per day.
Eating more carbs will potentially slow down your weight loss and mute some of the more dramatic health improvements associated with a strict low-carb diet, but it can still lead to better health, especially if you are eliminating processed foods and sugar. Once you are used to eating less carbs, you can take the additional step into eating less than 20 grams of carbs per day, in line with the ketogenic diet.
Note, however, that when you are in a low carb diet, you lie somewhere in that grey area where you are not eating enough carbs to provide you with abundant energy and you are not eating little enough carbs to throw you into ketosis, where all the unpleasant symptoms disappear. That grey area is a painful place to be in, because your body will be complaining about the lack of carbs like in the keto flu, but you never leave that place until you either go back to eating carbs or achieve ketosis.
4- Go easy on the physical activity
While feeling energetic is one of the hallmarks of the keto diet, you should be mindful of trying to use that energy for exercise in the beginning of your diet. Studies indicate that physical performance decreases in the early stages of the diet but increases later on. (1) (2)
Light exercises such as stretching or walking should be fine and may even be beneficial in making you feel better. But it is not idea to put your body under further stress when it is already trying to adapt to a new source of fuel.
5- Don’t consciously eat too little
Some people may find that they are not very hungry during the first stages of switching into ketosis. This will likely be due to the nausea or headache produced by the keto flu.
However, other people will feel they are quite hungry and might be eating too many calories or too much protein during the day, which is not good for weight loss on a keto diet and that might make them feel anxious or stressed. It is not a good idea to starve yourself trying to control your calorie intake.
In the first stages of the diet, as long as you are keeping carbs under 20 grams per day go ahead and eat as much of the allowed foods as necessary to make you satisfied. Over time, with a higher fat intake and your body in ketosis, your appetite will likely go down and you will gradually move towards feeling satiated with less and should eventually see a reduction in the amount of calories you consume.
Note that the ketogenic diet is NOT overall an excuse to eat as much as you want. The fundamental equation of calories in < calories out still holds true.
See also other side effects of the keto diet.