The Physics Diet

bq. Most dieters are so concerned about second-order effects, such as daily fluctuations in weight and changes in metabolism, that they lose track of the first law of thermodynamics: conservation of energy.

bq. Want to lose a pound of fat? You can work it off by hiking to the top of a 2,500-story building. Or by running 60 miles. Or by spending 7 hours cleaning animal stalls. […]

bq. Exercise is a very difficult way to lose weight. Here’s a rule of thumb: exercise very hard for one hour (swimming, running, or racquetball)– and you’ll lose about one ounce of fat […]

bq. If you run for an hour, you’ll lose that ounce of fat and also a pound or two of water. By the next day, when you’ve replenished the water, you might think, “the weight came right back!” But you’d be wrong—you really did lose an ounce. It is hard to notice, unless you keep running every day for a month or more, and don’t reward yourself after each run with a cookie.

bq. There is a much easier way to lose weight, as we can learn from the first law of thermodynamics. Eat less.

The rest can be found at “The MIT Technology Review : The Physics Diet”:

posted at 1:36 pm on Saturday, November 15, 2003 in Links | Comments (2)


  1. Jeff K says:

    The conservation of energy? I’ve never heard anything so ridiculous. Chemical energy is stored in chemical bonds, which are goverened by E=mc^2, or more precisely, the conservation of mass-energy. ..and anyway even that is irrelevent. That’s BAAAAD science. You want to know what the body does with the results of combustion of x calories in an ounce of fat (mass is conserved (- the E=mc^2 part, which can be ignored on the bathroom scale))

    I propose a new title for your diet science: The conservation of crap. If crap is conserved, one is full of sh.. er, I digress.

    Some people believe and hope that fat is converted to muscle. I can only go by my own experience, which is that
    1. Excerise produces more muscle and less fat and a 20 minute regime each day can change the body drammatically in 6 weeks.
    2. I eat the same as thinner people.

    Anyway, I invoke Newton’s first law of motion, according to my calculations, a body in motion stays in motion, so running 60 miles should consume 0 calories.

    Isn’t science great?

  2. Harald says:

    The “physics” side of the article is over-simplification, perhaps; it was intended as humour. But the point of the quoted section is simple: exercise alone isn’t going to lead to weight loss, especially if you’re treating yourself after workouts.

    The vast majority of the food calories you consume get used merely keeping you alive (the so-called basal metabolic rate). The more you weigh, the more energy you need (and yes, fat cells need energy too). This is why many people on weight loss programs “plateau”; they have to reduce the amount they consume as their weight drops. Also, overweight sedentary people can eat as much as skinny active people; the excess body mass consumes more energy than the exercise.

    Ignore all the fancy diets; the weight-loss equation is simple. Consume fewer calories than you expend, and you’ll lose weight. Consume more, you’ll gain weight. Everything else is management.

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