How accurate is Myfitnesspal and Gym equipment when it comes to burning calories through exercise?

StevenC987

Hi folks I was wondering how accurate Myfitnesspal and Gym equipment are when it comes to burning calories through exercise. I tend to be a bit skeptical so when it says I burned 500 calories. I note it down as 250 burned off am I being too hard on myself is it closer to 80% rather than say 50%?.

sijomial

There isn't one universal number for all the various and very different pieces of exercise equipment and exercise types. Or different people....
Which is why the "group think" advice of eat back 50% doesn't actually make sense in terms of improving accuracy - it simply makes the numbers much smaller.
One of the cardio devices I use at the gym is extremely accurate and halving a good estimate clearly wouldn't be sensible.
I've also used some equipment that is over by about 20% and some that are worse than that but I've never had an estimate I believe to be double reality.

For the database here a lot of the content is based on METS values from the Compendium of Physical Activities and although they will be research based that has two generic problems:
They are gross calorie estimates whereas the MyFitnessPal method of accounting for exercise really wants net calories.
METS are based on a person's weight and weight isn't a great indicator of fitness and physical ability. There's a guy at my gym who leg presses 600+ kg but a less strong but same weight person would get the same calorie estimate pressing far less weight.

Best to focus on you and your particular exercise selection to improve accuracy to the realms of reasonable (precision isn't required for purposes of calorie balance management).

What did you do to get that 500cal estimate?

StevenC987

The 500 was an example. My planned exercise for the day is a 40 minute walk at a moderate pace
and 30 minutes on the cycling machine I get roughly 600 calories burned which I dont believe is accurate. I dont plan on eating back 50% of what I burn off, this is more just to aid me in hitting my 1500 cal a day target.

sijomial

For walking I would use the net calorie option from this calculator (long duration, low intensity exercise is where the difference between net and gross causes a bigger percentage deviation). You can overwrite MFP's suggestion with your own numbers.
https://exrx.net/Calculators/WalkRunMETs

Cycling is my main sport and there is a massive range of what is possible from someone pedalling easily (lets say 288 net cals / hour) to a highly fit persoon pushing hard and burning over 1,000 cals an hour to an elite cyclist churning out 1,440 / hour).

METS for a non-weight bearing exercise is pretty useless as performance is mainly down to fitness level but if your bike shows your power in watts then you can get a very good estimate from the average watts (watts X 3.6 / per hour).

Without knowing anything about you and your capabilities all I can say is that 600 in just half an hour would be highly impressive! On a level which a very good club cyclist pushing really hard for the whole duration perhaps.

StevenC987

Oh sorry for not being clear the 600 calories was the combined 40 minutes of walking and 30 minutes cycling

Retroguy2000

tldr - They tend to inflate calories burned, and you're probably being a bit hard on yourself.

It's important to consider MET. You'll do 1 MET per hour just resting, which is 1 calorie per kg per hour. A low effort exercise then, will not burn many more additional calories than resting. I've also read that on average cardio machines over-report by about 7%. Myself, I estimate my workouts as follows:

30 minutes on the stationary bike, it says 330 cals, I lop off 10% and report it as 300 to MFP. It's entirely possible you're working harder on the bike than I am.

60+ minutes of free weights at home. I call that 200 cals, which is a rough estimate based on MET's, from this source. Estimate your MET from the exercise, subtract 1 which is your MET while resting, and that's your additional burn.

Now that I see it written down, I should probably take off another 50 from the cycling estimate to account for my 1 MET resting rate, but I also picked a low MET of 3 for the weights, so it probably comes out in the wash anyway.

https://www.shape.com/fitness/tips/calories-burned-lifting-weights

Lietchi

For walking, you can compare with this calculator (choose net calories instead of gross, to avoid double counting BMR calories):
https://exrx.net/Calculators/WalkRunMETs

spiriteagle99

Generally neither is very accurate, though it might be for you if you burn more calories than most. I have always gone by MFP's numbers and that has worked for me, both to lose weight and maintain it. I seem to burn a lot of calories in exercise for someone my age and size. For me, your exercise example would burn 150 calories for the bike, according to my bike and MFP (about 11 miles in half an hour) and 75-100 for the walk (assuming 3+ mph). I have a treadmill that gives highly inflated burns, so I use MFP's numbers. (It also doesn't have the option of inputting my weight, so it may assume I weigh a lot more than I do.) What most people do is pick a percentage of the calories indicated and see how that works in real life. Some may be good with 100%, some with 75 or even 50%.