Sunday, December 23, 2012
I've read so many good books about exercise and nutrition this year. But for me the the absolute favorite is the book by Jeff Volek and Stephen D. Phinney "The Art and Science of Low Carbohydrate Performance."
This book came out early this year and I was lucky to find it shortly after.
This is the first and possibly still only book that talks in depth about why a very low carb ketogenic diet may not just be useful for weight loss, insulin-resistance, metabolic syndrome, heart disease, epilepsy and autoimmune diseases but also to significantly improve athletic performance. The authors have many years of research experience in the field of low carb nutrition and had published another outstanding book, "The Art and Science of Low Carbohydrate Living" last year which focused on the details of getting low carb eating right by avoiding the many possible pitfalls.
This new book is written for athletes who want to improve their performance, but also for people who want to be athletes and never could be because their body would not cooperate on a higher carb diet.
The authors explain in detail how on a higher carb diet the body is dependent on glucose for most of its functions including muscle functions and brain function.
Glucose can only be stored in our body in a fairly limited amount, somewhere around 2000 calories. When this supply is close to being exhausted we need to refuel with carbohydrates to keep functioning or we will "hit the wall" as endurance athletes call it, meaning our brain and muscles are running out of fuel. When eating a high carbohydrate diet our body can not quickly switch from fueling with carbohydrate to fueling with fat, even though even a slim person has 40,000 calories of energy on their body at all times from fat.
This fat can only be accessed to fuel the muscles and the brain for most of their energy needs if the body is used to using it. Fat is converted to ketones which can fuel the muscles and the brain for most of their energy needs in a keto-adapted person.
For keto-adaptation to happen carbohydrate intake has to be drastically reduced, usually at least down to 50 grams/day, in many people to under 20 grams/day at least initially. The reason is that higher carb levels than this will lead to more insulin production and insulin inhibits release and use of fat from our fat storage cells. The graphics in the book show that with even moderate carbohydrate intake (of any form) there is too much insulin for the body to be able to access any significant amount of fat as fuel.
Once carb levels are lowered enough the body will start producing ketones from fat and from that point on it takes a few weeks for our body to make all the necessary changes to become fully keto-adapted. The whole process typically takes about 6 weeks, which is why many benefits of a low carbohydrate diet are only optimized after this period. Some improvements, like a lack of hunger and a reduction in body fat, can be seen much earlier, often after just a few days.
Once the body is fully keto-adapted something amazing happens:
Fat use during exercise increases tremendously with moderate exercise for both endurance exercise and resistance training. In a study of high-level cyclists who had been keto-adpated for 4 weeks the average fat oxidation per hour at about 65% VO2max was about 90 grams/hour.
So far I have just summarized the first three chapters. The rest of the book talks about implementing the diet, macronutrient levels, faster recovery rates on ketogenic diets and fluid and mineral management.
Just to make sure nobody who buys this book is going to be disappointed: The diet itself is not very different from what you can find in the original Atkins diet: low carb and high fat although there is some additional info here as well. The main benefit I get from this book is to understand how to optimize a low-carb diet to get far superior results from the time I spend exercising.
I am planning to measure this by recording my body weight, body fat percentage vs. lean muscle mass and by recording improvements in my running and resistance training over the next 3 months.
I found out that for me even with carbs around 50 grams/day I am barely, if at all in ketosis so have lowered my carbs down to 20 grams/day for the next 2 weeks and will then increase by at most 5 grams/day per week. Today is only my second day in ketosis so I am expecting it to take about 3-4 weeks to see significant improvement in performance, although I should be seeing a drop in weight and body fat earlier.