8 Common Keto Side Effects & Risks

Keto flu is not the only side effect of keto, there are several others that you should be aware of.

02-Aug 2022, by Lee Sandwith

There are many reasons why people start keto. Weight loss is the main reason as it’s super effective, especially for people who have struggled to manage their calories.

However, despite all of positives, there are many potential risks, side effects and complications which means keto might not be suitable for everyone.

Disclaimer: This content does not constitute medical advice. As a nutritionist, by law, my scope is limited to providing information and advice on anything related to nutrition. Any actions you take as a result of this video are at your own risk. For any conditions that you are experiencing, please consult with your physician.

In this article, I briefly cover 8 side effects, symptoms, and potential solutions.


According to the research, constipation affects somewhere between 25-50% of people on a low-carb or keto.

In the majority of cases, it’s usually mild and self-resolves over time, or it is easily treated with home and over-the-counter remedies.

There are number of things to try if you’re suffering from constipation:

  • Stay hydrated
  • Ensure you get plenty of salt
  • Eat more fibre
  • Supplement with magnesium.
  • MCT Oil
  • Exogenous Ketones.


Muscle cramps, particularly in the legs, are a common side effect which are thought to be due to mineral imbalances.

To counter this, it’s essential to stay hydrated and ensure you get plenty of minerals ideally through nutrition.

You can easily add a good amount of minerals to your diet by adding pink Himalayan salt to your food and drinking water.

Reduced strength & physical performance

Reduced strength and physical performance are usually experienced during the initial stages and is thought to be a result of your body adjusting to using a new fuel source for energy.

With this one, time is the best healer as after a few weeks, as you start to become fat adapted, things should self-correct.

Keto breath

Keto breath is caused by the release of acetone through the breath.

Again, it’s usually experienced at the very beginning when acetone is released in higher amounts and should wear off within the first 1-2 weeks.

Hair loss

Although hair loss is a commonly reported side effect, research has suggested that the percentage of people affects is quite low, in the region of 5%.

However, the process of ketosis is not root cause, it’s thought that some of the side effects are to blame such as vitamin and mineral deficiencies, lack of biotin and protein, calorie deficits and the stress involved in undergoing such a major dietary change.

The good news is the hair loss should not be permanent and should resolve itself within a few weeks or month.

To minimise the impact, there are a few strategies that you can implement such as increasing biotin and zinc levels, and including bone broth, collagen and coconut oil in the diet.

Keto rash

Keto rash is an uncommon side effect but is a really annoyingly itchy one for anyone who experiences it.

There are a lot of theories about why people get keto rash but in reality the scientific research into it is limited so no-one really knows.

An interesting theory is that sweat can contain acetone which can irritate the skin in high concentrations.
Others causes might be related to inflammation, autoimmune conditions, gut health or even a side effect of diabetes.

In terms of how to deal with it, try to suck it up for a while as it usually disappears after a few weeks.

Cleaning up after exercise to remove any sweat from the body is thought to help, and wear clothes which reduce friction and minimise irritation.

If it gets really bad, the quickest way to make it stop is to increase your carbohydrate a little bit.

Heart palpitations

Heart palpitations are a surprisingly common side effect normally associated with the transition from a carb heavy diet to keto.

They may sound scary, but if you’re experiencing them due to a keto transition, they are probably harmless and there are a few things you can do to manage them.

Although the science isn’t conclusive on the root causes, the main theory seems to be that heart palpitations are related to electrolyte imbalances so, again, adding minerals into your diet might be the resolution.

Elevated cholesterol

Although the majority of people see improved cholesterol levels after switching to keto, a percentage experience the exact opposite. It’s not clear how many people are impacted, but it has been suggested that it could be as high as 30%.

What we are talking about specifically is a significant increase in Low Density Lipoprotein cholesterol (LDL), which most people might recognise as the “bad cholesterol”.

For the vast majority of people, any increase in cholesterol should correct itself over time, however, this might not be the case for everyone.

Whether or not increasing LDL as a result of keto increases heart disease risk is still very much an unknown quantity.

Given that heart disease develops over many years it’s very unlikely that as short term increase should not be a major concern, however, this is not completely understood so the best thing to do is to keep an open mind.

Personally, I have gone very deep into this subject and even completed my Masters dissertation on statins and cholesterol. As with all of these things, as you learn more, you know less. As you go deeper, things get much much more complicated.

I’ve recorded several videos on the subject so if you’re worried about your cholesterol levels these may be a good place to start.

And if you’d like to discuss how you can lower cholesterol through nutritional changes, you can book a free consultation with me here.

Take away

Firstly, I would suggest that you don’t worry too much about any of these side effects when you’re just starting out.

It’s just good to be aware that there are a lot of risks and potential side effects of keto and the research on most of these things is limited so we’re flying blind.

It seems that there are some blindingly obvious things which everyone should be doing to minimise the risks.

First, make sure you diet comprises 90% proper, wholefoods avoiding packaged foods and lots of keto desserts and snacks. This is a no brainer and something that I harp on about all the time.

Second, make sure you stay well hydrated and get plenty of minerals to keep your electrolytes in check. You can go a long way by adding pink Himalayan salt to your food and drinking water and by including foods rich in minerals in your diet.

About the Author

Lee Sandwith holds a Masters Degree in Clinical Nutrition and is a registered nutritionist with the Association for Nutrition. You can book a free 30 minute consultation with Lee here.

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