Dieting is Less Work

I was wondering how many calories I burn doing squats. If I did the calculation right, it’s not nearly as bad as it feels ๐Ÿ™‚ . I figured I’d burn off 50-100 kcal. But then I calculated…

My squat is about 1 meter in length, roughly half my height. A 1-kg weight exerts a downward force equal to gravity, 9.8 m/s2.

Work = force x distance = 9.8 * 1kg * 1 meter = 9.8 for a 1 KG weight

Now multiply for the number of kg i’m lifting. Let’s say 135 lbs = 61.4kg.

Then add the amount of my weight I’m also lifting (est) = 180 lbs = 82kg.

So the total mass is about 143.4kg.

Work = 9.8 * 143.4 * 1 = 1405.32 joules for 1 squat.

Convert to calories (1 cal = 0.239 J), that’s 335.8 calories per full squat. Note that these are *regular* calories, not kilocalories, as food is measured. So at some point I’ll have to divide by 1000. Also note that I’m only calculating the upward motion of the squat. Obviously the downward motion takes effort too, but for now I’ll assume that effort is not greater than the effort of the upward squat. So at the end we’ll at most double the estimate of calories burned to account for this.

Say I do 12 squats of 135lbs. That will burn 335.8 * 12 calories = 4030 calories. If I do 4 sets of this, that’s about 16000 calories burned. If we assume that the downward motion of the squat is half as difficult as the upward motion in terms of energy usage, we get a total of 24000 calories burned for a full squat exercise.

Now I know I feel equally wonderful and terrible after doing squats, but I also know I didn’t burn 24000 calories. I guess this is where that kilocalorie calculation comes in. Dividing by 1000 gives us 24 calories (in terms of food) for a full squat exercise at 135lbs. Still feels like more to me!

Some other estimates:

  • 135lbs: 24 cals
  • 205lbs: 29.5
  • 225lbs: 31
  • 275lbs: 35

And now, since squat is my hardest lift and I feel the most exhausted after it, I can use it as an upper-bound for calories burned on any exercise. So if I do 6 exercises in a day at the gym, and each of these is < = 4×12 squats at one of these weights, then the most I can be burning in a day is…

6 exercises X 25 cals = 150 cals.

Which is like a single can of soda or beer. Wow, I’m suddenly rededicated to dieting!

Comments

  1. avatar DevilDog says:

    Why can’t you apply the time you have for writing equations fro Cal loss, to writing and equation that will help me win the LOTTERY!!!

    Also, don’t the measurement have to be in lbs/f? or lbs/m?

  2. avatar Cubicle Warrior says:

    I’m not sure that there is an equation that would help you win the lottery. Or rather, one that could dictate the profitable pursuit of it.

    Also, since work is force multiplied by distance, the measurement would be lbs*ft – pronounce “foot-pounds.” Since the equations are all in metric, this comes to meteres*kilograms… or the more convienent term Joule.

    Check it out, it is all there in the conversions listed above.

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