[Quaganoca]

Here is a post from another board that I thought folks here would find helpful as it has been discussed before.

exercise fatigue
All,

I found an answer to my previous question about feeling fatigued during my (regular) workouts for the first two weeks of induction on the Atkins diet. I am posting this new thread in hopes it helps others.

I discovered a book called "The Ketogenic Diet" by Lyle McDonald, which is available only as an online download. It is very technical and describes a lot of the physiology behind Ketosis and the body's fuel sources. Highly recommended if you want to know what is going on inside your body during one of these diets.

He asserts (and I confirm) that a standard low-carb diet cannot sustain an aggressive exercise program. The reason is that the glycogen stores of the muscles are completely depleted, which is one of the goals of this sort of diet.

The fatigue problem is particularly acute during the first few weeks as your body switches fuels, from glucose to fat. At first, the ketones are used by all of the tissues of the body, and after a workout, this may lead to a fair amount of fatigue and "brain fog" because your body is not producing enough of them.

After about the third week, many of the body's muscles will switch from burning ketones to Free Fatty Acids and thus preserving the ketones for brain function. The brain cannot burn Free Fatty Acids, but it can use ketones for about 75% of its fuel. The rest must come from glucose (and that is why you need some carbs).

He calls this process "adaptation", and says it generally takes about three full weeks. I am just entering my third week, so I will let you know if my overall fatigue and workouts improve.

His book has a lot of additional detail and technical reasons, but I won't go into that here. It also contains some recommendations for tweaking the low-carb diet for people that do more strenuous exercise as well as aggressive weight training. It involves targetted carb consumption.

I hope this helps someone.

John L.