Ketosis is not, unfortunately, a little known Greek island. I am far from soaking up the sun on a mini-break on the Mediterranean and actually sitting in England watching the rain for the second consecutive day of the weekend. So if it’s not a Greek island, what is ketosis?

Well, if you are rejecting surgery as an answer to getting rid of the excess fat you are carrying, ketosis is the only way you are going to do it. Ketosis is the state in which the body is using primarily fat for energy i.e. “fat burning”. Ketogenesis is the process by which the body turns fat into energy. Here’s what it looks like:

The two molecules at the top are acetyl-CoEnzyme A and are the result of the breakdown of fat molecules either directly from food intake or, if you are losing weight from your stored body fat. The three molecules at the bottom in pink are what is known as “ketone bodies” and are what the body actually uses as fuel. Wikipedia tells us that:

“The three ketone bodies, each synthesized from acetyl-CoA molecules, are:

• Acetoacetate, which can be converted by the liver into β-hydroxybutyrate, or spontaneously turn into acetone
• Acetone, which is generated through the decarboxylation of acetoacetate, either spontaneously or through the enzyme acetoacetate decarboxylase. It can then be further metabolized either by CYP2E1 into hydroxyacetone (acetol) and then via propylene glycol to pyruvate, lactate and acetate (usable for energy) and propionaldehyde, or via methylglyoxal to pyruvate and lactate.
• β-hydroxybutyrate (not technically a ketone according to IUPAC nomenclature) is generated through the action of the enzyme D-β-hydroxybutyrate dehydrogenase on acetoacetate.

β-Hydroxybutyrate is the most abundant of the ketone bodies, followed by acetoacetate and finally acetone. β-Hydroxybutyrate and acetoacetate can pass through membranes easily, and are therefore a source of energy for the brain, which cannot directly metabolize fatty acids. The brain receives 60-70% of its required energy from ketone bodies when blood glucose levels are low.”

So, if you want to burn off your body fat, all you have to do is persuade your body to break down the fat into acetyl-CoA then turn it into ketones and use it for fuel. Simple!  Unfortunately Wiki also tells us however that:

“Ketogenesis takes place in the setting of low glucose levels in the blood, after exhaustion of other cellular carbohydrate stores, such as glycogen.“

Hmm… so how do you do that then? Wiki to the rescue:

“Depletion of glucose and oxaloacetate can be triggered by fasting, vigorous exercise, high-fat diets or other medical conditions, all of which enhance ketone production.”

Now I don’t ever suggest getting ill is a good idea so let’s rule out the last one “medical conditions” which leaves us fasting, vigorous exercise and high fat diets. Does that remind you of anything? Oh yeah… a “primal” way of living. This is interesting! But if we were actually meant to base our diets around carbohydrates then why did we bother to evolve ketogenesis as it looks pretty complex? Because in reality, for early people, carbohydrates were not common in large amounts and an unreliable food source, we experienced frequent bouts of fasting when hunting was poor and when hunting was good, we undertook large amounts of vigorous exercise to catch stuff. And finally, if we were lucky enough to find carbohydrate to eat we immediately shut down ketosis to preserve our fat stores because fat is the body’s insurance against bad hunting. If we reflect on that for modern people, basically, if you are trying to lose weight you can only do it by using fat for fuel and if at the same time you are eating carbohydrate you are telling your body to stop burning fat. No wonder people feel weird on a low fat/high carb weight loss diet!

OK I hear you say, that all pretty easy to write but can you demonstrate any of it? have a look at my week. The pictures are of what are called Ketostix and they measure the amount of acetoacetate (one of the ketones) in urine. The more purple the end of the stick the more ketones and the stronger your state of ketosis i.e. the more fat you are burning. This isn’t scientific but I tested myself at the same time every day for nine days. My diet was mainly very low carb. Ketostix are not an accurate way to measure ketones in your blood as they are measuring the overspill in your urine, but they do demonstrate that some ketosis is happening.

Monday – low carb diet and lunchtime workout that was pretty strenuous. Heavy fat burning.

Tuesday – the same as Monday and still heavy fat burning.

Wednesday even more so!

Thursday and its the same again. Same routine same result.

On Friday I change my workout to a lower intensity stretching session and my ketosis dials back as I don’t need as much energy from my fat.

Saturday and I take the day off exercise and down it goes again but still in ketosis – still burning fat as my diet is very low in carbs and so there is very little glucose in my body – one of the conditions for ketosis. But watch what happens on Sunday…

BOOM!! NO KETOSIS!! Or almost none anyway – what happened here to stop things so abruptly? Carbs happened. For breakfast I ate half a smallish potato rosti fried in butter. Maybe the equivalent of half a medium sized potato and my fat burning almost completely stopped dead. Check out how much carbohydrate it took… half a medium potato thats all! No fat was getting burned by my body as it was preferentially using the carbohydrate from the potato and preserving its fat stores. I took all my readings at 6pm and so I had lasted the whole day on half a medium potato without having to touch any fat for fuel.

Monday was back to the usual routine and back to very low carbohydrate and working out at lunchtime and back into ketosis and back to fat burning.

Tuesday I worked it a bit harder in the gym and I think I just about went off the scale…

So there we have it. Don’t eat carbs and burn body fat, eat carbohydrate and completely shut down your fat burning and preserve body fat.

So how people expect to eat a low fat/high carbohydrate diet and lose their body fat at the same time is simply a mystery to me. Unless of course what they are actually doing is actually starving themselves by reducing their intake of food to a level that does not support the normal functioning of their body  in an effort to lose weight…. that might explain why they feel ill, suffer depression, find it unsustainable and put all the weight and more back on when they stop starving themselves.

One lump or two?