Wednesday, September 3, 2008

Blood Glucose

I found a quote by Dr. Eades yesterday buried in the comments in his blog that I found interesting. He was helping a woman who was struggling with a low carb diet. After helping her set up her macronutrients, he wrote:

Based on caring for a large number of patients, I would assume that your body fat right now is around 33-35 percent. At 189 pounds, this means you are carrying about 60 pounds of fat and 129 pounds of lean body mass. At your ideal weight and body fat percentage, you will have a lean body mass of 104 pounds, which means you will lose 25 pounds of lean body mass. Which is okay since you won’t need that lean mass when you are 59 pounds lighter. (As a corollary, if you want to gain lean body mass all you have to do is strap on a 59 pound pack and wear it 24/7.)

The muscle mass you lose will be converted to glucose to make up for the glucose your body uses while getting only 30 grams per day. Under stable low-carb conditions, the body needs about 130 grams of glucose per day (normally it needs about 200, but ketones take up the slack for about 70). If you provide 30 grams in the diet, the body gets the other 100 grams from lean mass breakdown. 100 grams times 10 days equals one kilogram, which is 2.2 pounds. Add that to the fat you will be burning from the spontaneous caloric deficit a good low-carb diet provides, and you should find yourself losing 2-3 pounds per week.

Low Carb and Gymnasts

Anthony Colpo wrote a while back that ketogenic diets were catabolic (muscle wasting) and was jumped on by the low carb community. Here, Dr. Mike verifies that it is true.

Some of this can probably be avoided by dramatically raising your protein intake. Since glucogensis (converting protein to glucose) is very inefficient (I've seen anywhere from 35 to 70% efficient), it would take an additional 150 to 200 grams of protein a day on top of your regular protein intake to make up that deficit. That is an additional 600-800 calories, not counting any other calories that ride along with the protein source (i.e. fat). Not all of calories will "count", as some are lost in the glucogensis conversion, but it is still a net gain in the energy balance.

Now, most women reading this are probably thinking "So? I don't want to be bulky anyway". The problem is that if carbs are kept that low, you will need to burn that protein up every day, regardless whether you lose any fat in the process. This means you can lose muscle ahead of the fat, which can lower the basal metabolic rate which can make it harder to lose the fat later on.

You see a lot of people on the various low carb boards that claim they lost X number of pounds by just reducing carbs to a really low level but seem to be eternally stuck 25-40 pounds overweight. A big portion of those X pounds were probably muscle and now they have settled into a lower metabolic state.

As an aside, after the fat is gone, the body will readjust the muscle levels down, so losing just fat won't turn one into a muscle bound freak.

I know carbs are villified by low carbers, but there are advantages to a slightly higher intake over increasing protein intake. For one thing, carbs can be stored in the body as glycogen in the muscles and liver. From there, it can be used to maintain blood glucose levels and for quick energy when needed. Protein isn't stored, except as lean tissue (protein's amino acids circulate in the blood stream for a while but are eventually cleared). Also, some insulin is necessary for nutrient uptake into the tissues of the body (it is excess insulin that can cause problems). Finally, 100 grams of carbs is only 400 calories verses the almost double amount needed with protein).

Lyle McDonald recommends about 100 grams of carbs a day. At this level, the body is still ketogenic (yes, it really is), so the ketones are still used but you have enough carbs to make up the difference instead of using muscle. It is also a low enough level that high insulin doesn't become a problem.

So what does this mean for me, since I am not counting anything? It just verifies my decision to include some carbs along with my protein heavy meals. For example, last night, I had a small bowl of beef stew for dinner. K makes the stew heavy on the beef, but there are a few carrots and potatoes. Since I don't eat a lot at a time, I doubt there was more than 25 grams of carbs in the whole thing.

No comments: