How many calories does weight lifting burn?

The_Big_Nasty

There are tons of online calculators for this:
http://www.healthstatus.com/calculate/cbc

clwydjpnrs

Well physics will tell you exacty how many calories are burnt lifting weights (well the absolute minimum at least). ossibly more precisely than cardio, which is quite complex, and HRM are very rough guesses (difficult to directly measure how much work your actually doing from your heart rate, it depends on - how fit you are, your weight, running up or down hill, stride, temperature etc...).

But for weights James Joule (19th Cen English Physicist) gave us precise way of defining amount of energy used lifting weights -

joule = (weight in kg x distance in meters lifted) / time in seconds squared

i.e. 1 joule = lifting 1 kg one meter off the ground in 1 second

1 joule = 0.239005736 calories

therefore lifting 1kg, 1 meter in 1 second burns 0.239005736 calories

So to burn 239 cal you'd need to lift 10 sets of 10 reps (i.e. 100 lifts) of 10kg one meter with each lift taking 1sec to complete. Note you don't need to do it all in one go - you can rest as long as you like between each rep (it makes no difference to the minimum energy used).

This is the very minimum amount needed, obviously the body is nowhere near 100% efficient. Critically, you wont just be dropping the weights once you reach the top, so you will also be using some energy holding up the weight at the top and energy slowing the decent of the weights on the way down too.

So I dont think it's entirely unreasonable to imagine a scenario where you did ~3 sets on 10 reps within 5-10 minutes x 3-4 sets in totall within 30-40 minutes and burn 500 calories.

clwydjpnrs

Opps.. accounting for gravity its actuallt 10 joules or 2.3 cal. and the other thing to note is that its cal rather than Kcal!

clwydjpnrs

So physics will show the bare minimum energy required, but total energy used by the body to actually lift the weights is going to be much higher.

mustgetmuscles1

I lost 50lbs and have been doing bulk and cut cycles for a couple years now using the estimate that MFP gives. It estimates a little over 200 cals per hour for weightlifting. I have found that using that estimate, and eating back my calories, weight gains and losses are near what they were expected to be. If it was off by 300 calories Im sure I would have noticed by now.

This is heavy weightlifting though. If you are doing some sort of circuit training then you need to use that as your input.

Chieflrg

*double post

clwydjpnrs

just to reiterate - cal in physics is not Kcal. i.e. the word cal we normally use everyday is actually Kcal. so the energy used, in terms of the physics, to move weights is very low. so maybe the 500 cal figure that's been quoted comes from that kind of confusion.

Obviously the actual amount of fuel burnt will vary from person to person, but the figure quoted by mustgetmuscles1 who speaks from experience is likely to be the most accurate kind of estimate.

noexcusesjustresults2014

Cerdwin wrote: »

So I was at the gym today and my personal trainer off handly said that you burn 500 calories in 20 minutes weight lifting. Is that even close to being true? :huh:

Your trainer sounds like an idiot. There is no chance you can burn 500 calories weight lifting in 20 minutes.

If I were you I would look for a new trainer