Fat burning mode – ketosis 101

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I’m very grateful for this week’s blog post, which comes from Paddy McCay, who is my guest blog poster for this week.

Paddy is chief biohacker and coach at the Nutrition and Productivity blog. He is on a relentless mission to optimize his productivity and wellbeing through nutrition, exercise and tech.

Paddy wrote a blog series on ketosis and it really builds upon my previous blog post Intermittent Fasting with Bulletproof Coffee.

I’m sure you will find this fascinating:

What is ketosis?

Imagine being in a state of high energy and high mental clarity where you’re burning fat and you don’t feel hungry. Sound like a good state to be in? This is what it’s like to be in ketosis. Ketosis is a metabolic state where the body switches to burning more fat in the form of ketones rather than just burning glucose (a sugar). Ketosis is great- but hard to get into (if you don’t know how).

How do you know if someone does cross-fit, is married or is in a ketotic state? They’ll make sure to tell you all about it.

Ketosis kicks in either when the liver has exhausted it’s supply of carbs (glycogen). Or when stimulated from a dietary source. Fats (triglycerides) are converted to molecules called ketone bodies in the liver. Ketones are burned as fuel in place of glucose by “cellular batteries” mitochondria.

Ketotic benefits

Not only does ketosis burn fat, it has the following benefits:

  • Increased healthy cholesterol levels. It can improve HDL levels (the good cholesterol) [1].
  • Keeping hunger at bay. Ketosis regulates the levels of the hunger and satiety hormones ghrelin and cholecystokinin (CKK) [2].
  • Improved brain health. It reduces brain fog by promoting healthy neurotransmitter levels (gaba) and also up regulates mitochondrial production thereby increasing thinking power [3].
  • Stable energy levels – for two reasons.
    • The first is how blood ketone levels are maintained: when blood-glucose levels reach a certain level, insulin signals to the cells and liver to absorb glucose from the bloodstream and this can cause energy levels to crash. Because ketone bodies can’t be converted back to fats and have to be excreted through the breath and urine, blood levels remain consistent.
    • The second reason is that β-hydroxybutyrate (BHB), one of the main ketone bodies, is potentially burned much more efficiently by the mitochondria than glucose [4]. The glucose burns like highly flammable kindling that needs to be constantly replenished to keep the fire going whereas ketones burn slowly and steadily like coal.

Getting into ketosis isn’t straight forward

Due to the carb heavy western diet, getting into ketosis is a state the general population rarely enter into. Eating a high amount of carbs tells the body ‘there’s plenty of sugar going, no need to burn fat – let’s keep that stored for when we need it’. But cutting the carbs itself is not enough. Eating too much protein can prevent the body entering ketosis as this spikes insulin and tells the body not to burn ketones. So if you’re eating much less carbs and less protein you have to eat much more fat. However, the controversies and confusions around fats can still be off putting to people to go high fat even after there’s good science to support dietary fat intake [5]. Social norms are hard to overcome.

Even if you’re eating high fat and low carb, it can still take awhile to get get the body comfortable with ketosis. It takes time for the up-regulation of the genes [6] and enzymes needed for converting fats to ketones [7].

Hacking ketosis

Luckily, there are some ways to ‘hack’ the state of ketosis:

  • Fasting – once the body runs out of glycogen the body then turns to the fat stores.
  • Exercise can stimulate ketosis, particularly High Intensity Interval Training (HIIT). Although best to combine this with diet.
  • Taking exogeneous ketones such as ketogenic fats such as Bulletproof® Brain Octane® and ketone salts can get you into ketosis.

Levels of ketosis

  • Slight / mild ketosis: blood ketones are in the range 0.2-0.5 mMol/L.
  • Nutritional ketosis: When levels of blood ketones hit 0.5 mMol/L, nutritional ketosis kicks in. At this point the level of blood ketones resets the body’s hunger hormones (leptin and ghrelin), leaving a feeling of satiation [8]1
  • Optimal ketosis: When blood levels hit 1.5-3.0 mMol/L, this is when the effects of mental clarity and focus really kick in.
  • Ketoacidosis: Blood ketones over 10mMmol/L can lead to the blood becoming highly acidic. Ketoacidosis is a life threatening condition most common in untreated diabetics and alcoholics and is difficult to achieve through a ketogenic diet alone.

Measuring ketosis

There are 2 ways to measure how deeply you’re into ketosis:

  • Ketone urine strips (e.g. Ketostix): these are the cheaper option, costing between £10 and £20 for pack of strips. These you have to pee on and as a result they don’t measure blood ketones directly – but only the excess ketones excreted by the kidneys. As a result, there can be situations where you’re in ketosis but it won’t appear that way. Levels of hydration can also lead to skewed readings as ketones can become diluted. Another drawback is that you have to wait until you need the toilet before taking a reading.
  • Blood ketone monitor (e.g. Precision Xtra): this consists of a reader and blood strips that measure beta-hydroxy butyrate (BHB – the main ketone body). The reader costs about £50 and the blood strips £5 each – so a much more expensive option that the urine strips, but much more accurate and you can take a reading whenever you need.

I find both options give a good indication of ketone levels. Ketostix are recommended if you’re on a budget.

Thanks for reading, Paddy
Nutrition and Productivity blog.


  1. https://www.ncbi.nlm.nih.gov/pubmed/19641727 ‘Long-term effects of a ketogenic diet in obese patients.’
  2. https://blog.bulletproof.com/ketosis-helps-lose-weight-suppressed-appetite/ ‘How Ketosis Helps You Lose Weight Through Suppressed Appetite’
  3. http://www.marksdailyapple.com/the-fat-burning-brain-what-are-the-cognitive-effects-of-ketosis/ ‘The Fat Burning Brain: What Are the Cognitive Effects of Ketosis?’
  4. https://blogs.scientificamerican.com/mind-guest-blog/the-fat-fueled-brain-unnatural-or-advantageous/ ‘The fat-fueled brain: unnatural or advantageous?‘
  5. https://www.theguardian.com/society/2016/apr/07/the-sugar-conspiracy-robert-lustig-john-yudkin ‘The Sugar Conspiracy’
  6. http://ajcn.nutrition.org/content/77/2/313.short ‘A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle’
  7. http://watcut.uwaterloo.ca/webnotes/Metabolism/Fat.html#sec-fatKetoneBodyMetabolism ‘Ketone body metabolism’
  8. https://blog.bulletproof.com/the-definitive-guide-to-mcts/‘Brain Octane vs. MCT Oil: What’s The Difference?’

About Nick

Nick Powell is the founder of Stronger Self and he works with entrepreneurs and senior leaders to enable them to take their personal and professional performance to the next level.

Nick’s approach uses cutting edge tools and techniques from the worlds of biohacking, productivity, anti-aging and neuroscience; harnessing the exciting intersection between biology and technology.

Nick has developed his Peak Performance Coaching Programmes to enable his clients to deliver extraordinary results across all aspects of their personal and professional lives.

He runs his Coaching sessions face to face in London & Surrey and across the World via Zoom.

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