Low-Carb Eating & Running – First 2 Weeks

On Saturday August 20, a day before my epiphany, and at 171 lbs, I went for a 20 mile group run in Hinckely. I was a bit tired, walked a bit, but finished the 20 miles at a pace of 8:54.

On Sunday August 21 I started eating low carb. On Tuesday I ran to the Rec Center and back through the trails, a total of 13 miles and felt good. On Wednesday my wife and I normally do our 5 mile tempo run at the towpath. Instead of going in the morning, we went in the afternoon. It was a hot day (70F +) Something weird happened: I warmed up one mile, then tried to run fast but I could not go too fast. By mile 3 I had to stop and walk. I was soaked in sweat. And the sweat was salty. And I was thirsty. I was definitely sweating more than it can be explained by the temperature or anything else. What is going on?

Books on running (like “The Lore of Running”) tell us that when we run, we burn a mixture of glycogen and fat. More glycogen at first, or the faster we go. Glycogen is tied to water in a ratio of 1:4. Every gram of glycogen burned releases 4 grams of water. This kind of sweat in my experience does not carry a lot of salt, plus it does not make me thirsty. So something more was happening here to explain that the sweat was salty and I was thirsty. Books on low-carb running say that the initial weight loss on a low carb diet is due to the release of salt and the associated water. Salt is stored in our bodies (liver) and it is being released. I think this is what I was experiencing.  I experienced this one more time on week 2 and then it was gone.  Definitely a transient phenomenon.

By the end of the first week I had dropped 7 lbs but I was worried about the weekend because I had two major running events:

• Saturday: I had a 20 mile training run along the blue line, in preparation for the Akron marathon
• Sunday: I was running the Buckeye Half Marathon.

Friday night I decided to eat a bit more carbs so I ate a bowl of brown rice and had an extra fruit. On Saturday and Sunday morning I ate carbs for breakfast, a bit of oatmeal with chocolate, honey, some peanut butter and yogurt. I took plenty of water and had Gatorade during the runs.

I was surprised to find out that everything went fine! My 20 mile training run was strong, I was not to thirsty, and my pace was 8:30 and finished strong (compare this to the previous 20 miler, a week ago, pre-carb, 8:54 pace and walking). The half marathon race on Sunday also went well. My pace was 7:40, a bit on the slower side (compare with 6:53 in the 10 miler, two weeks ago) but I felt strong overall (especially considering that the previous day I had run 20 miles)

After two weeks of eating low-carb, my running was strong, so I felt I had nothing to worry about.  But the real test would be in the next 4 races:

• Leave no Trace Half Marathon Trail Run
• River Run Half Marathon
• Youngstown 25K
• Akron Marathon

Reports on these races follow next. Just a clue to increase your interest: Things got even better!