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Should I follow a ‘Ketogenic’ Diet? – Part 2

Should I follow a ‘Ketogenic’ Diet? – Part 2

3rd September 2019

In Part One we discussed the many reported benefits of the Ketogenic Diet.  In Part Two we are going to explore some of the side effects and negative impacts that the Keto diet may have. 



We are all different, and we can all respond differently to various dietary interventions.  While there are some guiding principles that are appropriate for everyone e.g. eat more vegetables, drink more water, eat less sugar, there is no one diet that will suit everyone equally.

Whenever you drastically change your diet, you are likely to feel some changes as your body adjusts, so it can be several weeks before you start to feel and see the real benefits. Below we discuss the side effects that you are likely to experience in the short term, and then detail some cautions about following the diet in the long-term. 



Many people, when starting the keto diet, may experience what has been nicknamed as “keto flu”.   It usually kicks in a few days into the diet and often involves:

  • Carb crash – These symptoms are especially likely if you’ve been relying on carbohydrates, sugar and caffeine as a source of energy.  
  • Tiredness/feeling weak
  • Headaches
  • Irritability
  • Nausea
  • Brain fog
  • Reduced physical performance

As your body adjusts to burning fat as a source of energy, the symptoms will eventually disappear, usually after a week or so.  Make sure you drink plenty of water during this phase.


  • “Keto Breath” – Acetone, a form of ketone, is released in the breath when you’re in ketosis. It is temporary and will pass. 
  • Constipation – Ensure you’re eating plenty of keto-friendly (Low GI) vegetables and drinking plenty of water to keep the bowel moving. However, if you’re prone to constipation anyway, this may not be enough to keep the bowel moving.  Soaked flax seeds can help, but you may find that you need to introduce some starchy carbs such as oats.
  • Diarrhoea – Some people find that their bowel movements become more frequent or more loose. This may be a general temporary adjustment, however if it continues, it may be a sign that you do not process or break down fat well.  Try a dessertspoon of unpasteurised Apple Cider Vinegar in warm water before each meal to help your digestion.
  • Cramps – make sure you’re eating plenty of vegetables to balance minerals. ½ teaspoon of Himalayan Salt in warm water taken at bed time can help balance minerals.  Also consider rubbing Magnesium Gel/Spray on affected areas.
  • Increased thirst/frequent urination – are signs that the body is in ketosis. Dropping insulin levels will affect the absorption of sodium which can have a diuretic effect.  Drink plenty of water, and keep up mineral levels as above.
  • Heart palpitations – a sign of dehydration and mineral imbalance. As above, water and veggies are the answer. [1]



The Ketogenic Diet for general health and weight loss is a relatively recently phenomena and there is little research into the possible long-term effects. 

Those advised NOT to follow a Keto diet include people with:

  • Active gall bladder disease
  • Impaired liver function
  • Impaired fat digestion (see below)
  • History of pancreatitis
  • Type 1 Diabetics (however, there’s some research suggesting that even Type 1 Diabetics may benefit from a Keto diet but discuss first with your GP.)[2]
  • Poor nutritional status
  • Gastric bypass surgery
  • Abdominal tumours
  • Decreased gastrointestinal motility
  • History of kidney disease/failure
  • Pregnancy and breastfeeding [3]



– The Keto diet may reduce your need for medication, so discuss with your GP before undertaking the diet and monitor your blood sugar levels or blood pressure regularly.  


GENETIC DIFFERENCE – How well do you process fat?

Developments in genetic testing have highlighted just how different we can be.  We now know, for example, that certain variants in our genes can mean that we don’t process fat very well.  These people may potentially gain more weight when following a high fat diet (even healthy fats) than someone without these genetic variants.  Alternatively, while these people may lose weight initially with the Keto Diet, they may struggle to maintain their weight longer term.  For a person with this genetic variant, the excess intake of fat may also result in increased blood lipids although the research results are mixed (see below).  

(By the way, some gene variants can also mean that you don’t process carbohydrates well.  If you’re curious about whether or not you have the genetic variants for fat or carbs (or both!), make sure you book our Nutrigenomix DNA test when you visit Homefield). 



– Many studies have shown that a keto diet improves blood lipids (cholesterol) but some people may experience a temporary rise in total cholesterol during the first 6 months.  However, while total cholesterol may go up, the rise is generally in the HDL (good cholesterol) with reductions being seen in LDL (bad cholesterol).[4]


There have not been enough long-term studies to establish the effect on blood lipids of following a ketogenic diet for any protracted period of time. 



Over the last decade there has been a deluge of research into the importance of the gut bacteria (microbiome) for our over-all health.  We now understand that the health of our gut bacteria can influence:

  • Our weight, appetite and metabolism
  • Our mood/serotonin production
  • Energy levels
  • Levels of certain nutrients such as B Vitamins and Vitamin K
  • Our immune defences
  • Our cardiovascular risk
  • Our brain health
  • Our cancer risk
  • Development of auto-immune conditions
  • Nerve health
  • Insulin sensitivity


While there is still much to be learnt about the exact mechanisms of how gut bacteria influence these risks, we do understand that the balance of our gut bacteria is under constant threat from myriad sources including:  antibiotics taken as medication and also in our food, steroid and pain-killing medication, pesticides on our food, contraceptive pill, stress, caffeine, alcohol, and excessive exercise.   

We also understand that the best way to support our microbial balance is through diet and lifestyle and that the foods which best feed our gut bacteria tend to be carbohydrates e.g. wholegrains, vegetables, fruits, beans, pulses as well as fermented products and live yogurts/kefir. 

Constipation in a sign of a gut in distress and constipation is a common side effect – in both the short and long term – of the Keto diet.  Therefore, we do have concerns about following this diet for any protracted period.



At our luxury health and wellness retreat we often see clients who follow extreme diets doing very well in the short term and then falling dramatically off the wagon.  The Macronutrients – protein, fat and carbohydrates – are all sources of fuel/energy.  The preferred source of fuel for the brain is carbohydrate, so after a period of carb deprivation, the brain can start to send out signals that it needs some carbs.  What it actually needs is the slow release carbs we get from wholegrains, vegetables, fruits, and a couple of tablespoons of brown rice or some roasted butternut squash would do the trick, but instead, in our “deprived” state, we will often go for the quick hit carbs – crisps, chocolate, biscuits and cakes.  And suddenly we are bingeing on all those foods, and before long we’re back where we started! 



If you’re in good health and have none of the contra-indications listed above, it may well be worth your trying the keto diet.  But remember that the key to good health and longevity is balance and moderation in all things, and any extreme diet is not likely to be sustainable or advisable in the long term. 







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