What is keto flu, and how can you manage it?

For many of us, the early stages of a keto diet, or a low carb diet (where total carbs are low, but higher than 5% of your total calories) there is a period of adjustment where you might feel worse, before you feel better.

“Now hang on, what gives” you ask?
Many of us attempt this approach to eating for its mental benefits and energy as well as the benefits it offers for body composition and weight loss. These benefits will definitely happen, but there is a period of time where your body needs to “re-learn” how to use fat as a primary fuel source, as opposed to a steady stream of glucose or carbs.

Often for anywhere from 2 days to a week, you can feel like you’ve got the flu. We call this keto flu and symptoms can include;

  • Fatigue
  • Headaches
  • Dizziness
  • Difficulty concentrating or brain fog
  • Irritability
  • Sugar cravings
  • Difficulty falling asleep
  • Stomach pains or changes to bowel habits.

Not everyone will experience keto flu and the extent to which it happens will largely depend on your diet prior to starting your new eating regime. If you were already eating a diet based on whole foods but still included starchy vegetables and fruit your transition will be much smoother than someone who downed a family size bucket of fried chicken and a 2L Coke before declaring themselves keto.

What we are aiming for with the recal approach to nutrition is metabolic flexibility. What we mean by this, is fixing your metabolism so your body can utilise both ketones (fat) and glucose (carbs) effectively and quickly regardless of your food inputs. Once the glucose has been processed to your cells your body will return to burning stored fat as it’s primary fuel source.

In order for this adaptation to occur, your body must go through a transition from expecting a regular supply of glucose to thriving on ketones. When it hasn’t used fat as a fuel source for a while, this metabolic process can be sluggish resulting in keto flu.

Another reason why keto flu can occur is due to minerals - specifically electrolytes - lost through sweat and urine as your body excretes extra water stored by carbs. This can through your electrolyte balance out of whack resulting in headaches, cramps and fatigue.

For a detailed look at what keto flu is and why it happens read this article.

So what can you do? 5 strategies for overcoming keto flu.

1. Consider easing into a ketogenic diet by gradually reducing your carbs.

Cliff Harvey uses a carbohydrate ladder in his work The Carbohydrate Appropriate Diet. In it he defines a ladder of worst carbs to include in your diet, up to the best. Sugar is at the bottom, fruit, tuber vegetables and dairy products are at the top. When transitioning into a ketogenic diet, begin by removing sugar and refined grains for 2-4 weeks before restricting fruit and starchy vegetables. The process of metabolic flexibility will already have started over this period, meaning your keto flu should - in theory - be less.

2. Eat more calories

A common mistake we see with clients is when people have been eating a low fat diet for years a transition to a higher fat diet can leave them feeling full. This often means they haven’t ingested enough calories for some basic bodily functions. This may be true for your situation if your keto flu symptoms tend to be more fatigue, brain fog and dizziness as opposed to sugar cravings and headaches. Try to stick to the recal meal template just for the initial period. You may find as you get better at fasting and your body is better able to tap into your own body fat stores for calories, you can eat less. But while you are adjusting, be sure to get what you need.

3 Eat more fat

Yes. More. I mean it. Many of us still have hang ups from the low fat era. We do really well at the carb restriction part, but don’t replace that energy with a different source of fuel. You will transition through keto flu more quickly if your body has fuel to produce ketos. So go on, more fat.

4 Add salt to your water and your meals

This helps to replace the electrolytes your body is losing through stored water. You could also supplement with magnesium if you are experiencing cramps, restless legs or headaches.

5 Opt for gentle exercise.

A lot of work is going on behind the scenes. While your body builds its metabolic machinery, go easy on the high intensity training or heavy weights. You absolutely can do these activities with a ketogenic diet, however it isn’t necessary to experience the benefits and can be detrimental in the initial phases. For two weeks simply walk, do yoga, sit in a sauna or go for a gentle swim. You’ll be back at the gym in no time.

If you have any questions, feel free to email us at


  • There are no comments yet. Be the first one to post a comment on this article!

Leave a comment

Please note, comments must be approved before they are published