Exercise on a low carb diet

I thought that I could do a post on exercise on a low carb diet. This is because one of the most common questions that I get asked is "don't you have a lack of energy?" and I can understand the reasoning behind asking this as carbohydrates are normally seen as the primary energy source used by the body. 

Whilst it is true that the default source of energy for the body is sugar (in the form of glucose) our body is also capable of using fat and indeed protein as an energy source. The process of switching from using carbs to using fat as your main energy source takes time, around a couple of weeks is my understanding and during this time you may go through ketone flu (post on that to follow) and you will default back to carbs if your carb intake goes over a certain level. 

Just to side track slightly but once you have been doing this diet for a few weeks you are through this low carb flu and probably losing lots of weight (I lost 2 stone in first 6 weeks and regret cheating over Christmas) and there is added motivation to stick to it as you know it will take a couple of weeks to get back into it if you do cheat. I'll do another post looking at when I cheated as the difference in weight loss compared to surrounding weeks is massive. 

Right then back to exercise. You can skip exercise in those first few week whilst your body is adjusting and exercise is not always required to lose weight on this kind of diet, however you will find that you will lose a higher percentage of body fat compared to muscle if you are exercising. In the long run this is better because you are going to be leaner and muscle burns more calories. 

There are several easy ways to get into exercise, I went through the route of running and couch to 5k. 

The couch to 5k system builds you up through run walking until you are able to run for 30 minutes or 5k. Swimming can also be great if you are really overweight (like I was) or have issues that meant you don't want to run, equally I didn't want to swim because of the poor body image I had of myself. Some reports I have seen suggest that you are better off losing a bunch of weight first anyway because you will put significantly less stress on your body. 

Energy when running on low carb:

The exact number might be off but the estimations should be sufficient. Your body stores at most around 2000 or so calories in the form of sugar and as mentioned above it takes a whilst to transfer to efficiently burning fat, so you can run out of energy fairly easily, in fact this is exactly what hitting the wall is. In contrast you can store 20,000 calories in the form of fat (even if you aren't massively overweight). I mean think about this, the common number I see is that it takes 3500 calories to burn 1lb of fat so even if you only have 10lbs of fat on your entire body that is 35,000 calories. So on a low carb diet you are less likely to hit the wall. It is true that burning fat can be less efficient than burning sugar however tests have been done (see the art and science of low carbohydrate performance) that show that this has minimal if any impact on endurance performance. 

So basically in our experience there was no impact on running on a low carb diet in terms of performance etc, in fact we both feel like we have more energy now. As for speed, well because of the weight loss my 5k time has probably come down by about 10 minutes (guessing slightly from recent runs) and that is lowering my best ever PB by about 5 minutes and Katie is going quicker than ever as well. 

In fact we are both so confident that we have signed up to run a half marathon next year (enough said?)

(I realise that I am missing a lot of references on this but the knowledge is either from my degree or from the masses of reading I have done over the past 6 months whilst on this diet, if see something that is wrong I am happy to look for the evidence to back it up or if need be remove it, after all I am not a doctor).