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Old 04-01-2013, 04:22 AM   #6
Senior LCF Member
Join Date: Dec 2012
Location: Canada
Posts: 875
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I am an endurance athlete and also trying to work my way towards being able to compete in a body building competition, which means I am trying to lose fat and preserve my LBM. I am finding it very difficult for a number of reasons. A lot of competitive endurance athletes when they think about weight loss, although they prefer losing fat mass, it doesn't really matter what type of weight they lose. Lighter means faster. If you have read any of Gary Taubes books. I recommend them because he explains in a lot of detail why endurance exercise works against you when you are trying to lose weight. And I have found that the research he quotes in his books is exactly what I have experienced: The more you exercise, the fatter you become. The exception is that if you can restrict calories, you will lose weight but its an emaciation type of weight loss, meaning you lose fat and muscle.. It results in what is commonly now called a "skinny fat" body. To a marathon runner, skinny fat doesn't matter, because it is the overall weight that is the advantage in running. Ie. lighter weight = faster time.

In Gary's books he alludes to the ketogenic diet being a solution to the above, but what I have found is that eating no carbs, doesn't exactly fix the problem above. This is because to lose body fat you have to eat at a deficit. Eat less calories than you burn. There is no other way around that. And exercise, stimulates appetite. It doesn't matter what type of diet you are on, it is almost impossible to eat at a deficit when you are exercising a lot. Even if you do manage to restrict your calories, your body will shift into downregulation which means lower its metabolic rate to adjust the the lowered amount of calories, you can't get around that either.

Another issue has to do with the type of fuel used during exercise. With endurance exercise you use 4 types of fuel: muscle glycogen, free fatty acids, muscle triglycerides and blood glucose. Depending on the intensity, the ratio of these fuels change. With high intensity and anaerobic exercise you use a lot more muscle glycogen and with aerobic and lower intensity you use more free fatty acids. For marathon training you probably will be doing a lot of aerobic training which will burn a lot of fat. However, you also need muscle glycogen for aerobic training which sets up a bit of a paradox. You can't go completely ketogenic because you will be running a lot, you are going to need muscle glycogen to fuel your workouts, on the other hand if you eat too many carbs your body will spend a lot of time converting the carbs you eat into fat. This will teach your body how to shuttle its carbs off to become converted to fat. Combine that with the tendency to overeat and you will wind up with a fat storage issue. Gary discusses research some about how runners become fatter over time, this is most likely why.

Now, I don't necessarily agree with all of Gary's research. I think people who are really overweight can lose weight with endurance exercise. Because it isn't necessary for the body to carry a lot of extra body fat and it will readily shed the excess weight for someone who is 60lbs overweight. I think it becomes more problematic for people who are trying to get rid of their last 20lbs.

Just to give you an idea of the direction I am headed. I love being an endurance athlete, but I still have roughly 5lbs of body fat to lose. I also can't afford to lose any LBM. I have cut down my endurance exercise from 20hrs a week to about 5 hrs a week. And I have many days where I don't exercise at all. To get rid of the extra fat I am planning on sticking to some very low intensity jogging and light spinning on my bike trainer. Physical activity that occurs in the zone 1, burns almost 100 percent fat. It will allow me to lose the fat without putting a requirement on my body to build up my muscle glycogen, which is difficult on a ketogenic diet. You can do it, especially if you are eating an excess of protein, but the recovery is slower than when you are using carbs. And if you aren't over eating protein, your body will use some fat to build glycogen, but recovery in this case is really slow.

I ran a half marathon last year in the fall and thought about training for a full marathon this october but I am very concerned with losing lean body mass. From everything I have read it is very high risk when not fueling with carbs, if eating at a deficit. I suppose if you could keep all your training in the first zone, you could. But is that possible? To be in zone one you have to be able to have a full conversation with someone while doing the activity. That is why they suggest light activity for people who are using exercise to help lose body fat.

Anyways, if you haven't read Gary Taubes books: Why we get fat and Good calories, bad calories. I suggest reading them. If it is just about losing weight for you then you might be fine with your plan. My goals are different because I can't afford to lose any lean mass.
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