Feel the Burn!

The science du jour is physics of weight loss, which is useful for this time of year when some of us tend to act as sanctuary for some extra mass (those poor, persecuted cookies and brethren, seeking asylum)

Here’s my own The Physics of Weight Loss

Matt has just posted on the topic over at Built on Facts:

The Christmas Calorie

Calories and Climbing

54! Surely something that difficult would burn a lot more calories, you’d think. And it does. The immense effort you expend in climbing is mostly budgeted to different bodily processes. You have to move extra air in and out of your lungs. You have to circulate blood at a much higher rate. You have to process the complicated chemistry required to keep your muscles moving. All of these things take energy, and by the time the shoe meets the stair most of the energy has already been lost, eventually ending up mostly in the form of heat. Your body can’t afford to overheat and so you begin sweating to carry the excess heat energy away. All that energy had to come from somewhere, and it came from the food you ate. By the time you’re on the observation deck looking over Manhattan you’ll have used up a lot more than 54 calories.

As Matt notes in his posts, this is all about thermodynamics. Your body is basically a heat engine operating somewhere around 25% efficiency, so that 54-Calorie change in potential energy is going to require that you burn about 200 Calories of food.

(related: No Sweat)