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Enters Starvation Mode

2010-04-08 3 min read marco

One of the things calorie counters like to say is that if you don’t eat enough, then your body enters “starvation mode.” I held that to be a bit of hyperbole, akin to the notion of ketosis in Atkins Diets, but I could finally watch that happen in real time.

For that, I have to thank a combination of habits I’ve developed:

  • I wear my heart rate monitor at every workout
  • I perform some workout every day
  • I started calorie counting after my accident and the resulting loss of exercise and gain in weight

What happened? Lately, the weather turned really nice in San Diego. I mean, summer in March kind of nice. And when the weather turns for the better, I lose (temporarily) all interest in food. So I would get to the end of the day with sometimes 1,000 calories to spare – almost half my daily intake. I wasn’t trying, I wasn’t going for it, it just happened.

Now comes the interesting part: for the first few days, I lost weight very, very rapidly. It was about 8 pounds in just a matter of three or four days. Then, miraculously, the weight loss stopped completely. I didn’t lose weight, didn’t gain much, either. I just floated at the same level for three or four more days. That was quite frustrating at first, considering that I was still undereating a lot.

Then I noticed something strange. I start my workouts with the same routine all the time: I get a medicine ball and do 50 throwing crunches, where I throw the ball up in the air and catch it, while lifting my back from the floor. It’s a great abs exercise, is decent warm-up, and tells me at once how I feel that day.

Typically, on a set of 50, I will get up to about 120 beats per minutes (bpm). If the ball is heavier it can get to 130, in the opposite case I get up to 115. But when starvation mode entered the picture, I could only get up to 100 bpm. The pattern continued throughout the workout: no matter what I did, I could barely move my heart rate up. Even when it went up, it almost immediately fell down to a resting pulse.

Now, if you extend this to the whole day, then my body would have decided to actually save energy by shutting down the expendable fueling. If you need the energy, we’ll produce it. If you are not using it, we’re turning it off. Sorta like a smart furnace at home.

With two differences: first, you don’t lose weight any more, because your body doesn’t burn more than it gets. And second, the “empty” energy is actually used to fuel your muscles (including your heart) and make them run more smoothly. Working out in starvation mode is like chronically omitting your warm-up. You are cold at every machine, with the risks that go along with that.

Scary thought!

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