BMR and counting calories

Red Corvette

I found out what my BMR is. It's a little over 1500.

Can anyone tell me how do I do the maths if I want to lose weight?

For example, I had 1580 calories today and I burned around 600 calories today from exercise.

Do I eat back the calories I burned?

bladespin

Add your bmr to calorific expendature, take about 20% off that and you should loose weight.
600 cal from exercise sounds a lot but activity during the day will add to burnt cals too.
1500+600=2100 @ 80% gives 1680.

ainecaine

I've also read that to lose a pound you need to save/not eat 8000 calories

Alf Veedersane

ainecaine wrote: »

I've also read that to lose a pound you need to save/not eat 8000 calories

The ball park figure is 3,500.

bladespin

ainecaine wrote:

I've also read that to lose a pound you need to save/not eat 8000 calories

About half that, 3500 cals to 1lb of fat.

Michellenman

bladespin wrote: »

About half that, 3500 cals to 1lb of fat.

I read that too but found it very inaccurate. I had an average weekly deficit of about 7000 earlier this year with calorie counting and exercise and found that I was only losing between .5 and 1.25lbs per week. For the first couple of weeks I lost 3 or 4lbs but despite my calories staying the same and me upping the exercise (running, so not muscle building) my weekly loss dropped dramatically. While the 3500 may accurate for some people it's not a fixed number for all. Just something to keep in kind, OP.

bladespin

As your weight drops so will your bmr, you will need to adjust. The calorific value in 1 lb of fat is pretty accurate, unfortunately our bodies aren't, BUT if you remain under your TDEE by 4k cals or so you will drop 1 lb, problem is it's difficult to accurately calculate the exact TDEE and it is a moving target too.

Mellor

Michellenman wrote: »

I read that too but found it very inaccurate.

It's actually pretty accurate. The energy contained within 1 lb of fat.
This can be tested in a lab.

I had an average weekly deficit of about 7000 earlier this year with calorie counting and exercise

^^^^ That's the part that's not accurate.
How do know really how much energy you were burning on a typical day.
Or from exercise? Did you discount sedentary expenditure from exercise? etc
There there food intake and all the inaccuracies that go with it.

Look at all the people who say that eat a deficit but can't lose weight. It's more likely that they are miscounting, rather than breaking the laws of physics.

While the 3500 may accurate for some people it's not a fixed number for all.

It's more or less a fixed number.
But BMR isn't a fixed number. If somebody has a below average BMR. The calculations will overestimate their energy use, and thus their deficit.

Alf Veedersane

Red Corvette wrote: »

I found out what my BMR is. It's a little over 1500.

Can anyone tell me how do I do the maths if I want to lose weight?

For example, I had 1580 calories today and I burned around 600 calories today from exercise.

Do I eat back the calories I burned?

The basic maths:

Total Daily Energy Expenditure (TDEE) = BMR + whatever calories you burn through activity

If above was correct, you burned 1500 (BMR) + 600 (activity) = 2,100 kcals

Intake: 1,580 kcals

Deficit: 520 kcals

You don't need to eat anything back. You can if you wish but it will reduce the deficit.

But it's not an exact science. The better measures of calculating calories burned through activity (and indeed BMR) are good approximations but they are rarely exact. Calorie intake may not be entirely accurate.

So your best bet is to forge on, see the results on the scales and tweak as necessary.

Michellenman

Mellor wrote: »

It's actually pretty accurate. The energy contained within 1 lb of fat.
This can be tested in a lab.



^^^^ That's the part that's not accurate.
How do know really how much energy you were burning on a typical day.
Or from exercise? Did you discount sedentary expenditure from exercise? etc
There there food intake and all the inaccuracies that go with it.

Look at all the people who say that eat a deficit but can't lose weight. It's more likely that they are miscounting, rather than breaking the laws of physics.


It's more or less a fixed number.
But BMR isn't a fixed number. If somebody has a below average BMR. The calculations will overestimate their energy use, and thus their deficit.

Learn something new everyday I always thought the 3500 figure was an estimate.

Perhaps I am an anomaly. I weighed and tracked every morsel or food or drink that passed my lips (including oils and fats etc), wore a Fitbit 24-7 and a heart rate monitor while exercising so I know fairly accurately the calories I ate and calories I burned. Still my weight loss didn't adhere to what it should have been if it was 3500 cals per lb. I lost 23lbs over 15 weeks but it probably should have been closer to 33lbs if I lost a pound for every 3500 I was in deficit. This was 15 weeks of 1200 calories a day (except for 1 or 2 days in that period but I never ate more calories than I burned in any given day) and running upwards of 30miles a week plus Pilates once a week.

Tar.Aldarion

Calories burned is hard to measure, my tracker said I did 600 cals at lunch today, no way to know if it is actually accurate. Especially as it doesn't account for my efficacy at a certain exercise. Nor does it count muscle, fat and so on. My rule is basically that I have burned less than it says. Not to mention I have to take into account calories I would have used if I wasn't doing anything. I expend so much less energy doing the same exercise now than I did when i started out, I have muscles built up around it that means I barely sweat compared to the buckets I used to.

Mellor

HRMs and fitbits are based on estimates, they don't measure the actual energy you are using. They can be prone to overcount, esp over whole day. Mine definitely does for me. If you lost 23 lbs over 15 weeks, your bmr would have been dropping on a daily basis as you lost 1/4 lb or so. So every day, you're deficit got smaller until you recalculated.
The other issue is double counting.
Say I burn 2500 per day at rest. And today I went to the gym for an hour burning 320 cals lifting weights. For arguments sake, lets say both of those numbers are perfectly accurate.
Most people would add them together and assume I burned 2820. But that's forgetting I'd still have burned 120 or so had I sat on my ass instead. Which is counted for in the 2500. The real exercise expenditure is what I burn in excess of that, so 200 cals or 2700 total.

Red Corvette

Alf Veedersane wrote: »

The basic maths:

Total Daily Energy Expenditure (TDEE) = BMR + whatever calories you burn through activity

If above was correct, you burned 1500 (BMR) + 600 (activity) = 2,100 kcals

Intake: 1,580 kcals

Deficit: 520 kcals

You don't need to eat anything back. You can if you wish but it will reduce the deficit.

But it's not an exact science. The better measures of calculating calories burned through activity (and indeed BMR) are good approximations but they are rarely exact. Calorie intake may not be entirely accurate.

So your best bet is to forge on, see the results on the scales and tweak as necessary.

I'm also using my fitness pal and going by yesterday, I wasn't eating enough. It seems as if they want me to eat back the calories I burned.

Alf Veedersane

Red Corvette wrote: »

I'm also using my fitness pal and going by yesterday, I wasn't eating enough. It seems as if they want me to eat back the calories I burned.

I would just use MyFitnessPal to track intake. Other parts of it like estimating calories burned are not particularly accurate...it overestimates calories burned.

Macy0161

What I did was to not eat all the calories "earned". I tried to "earn" 500 a day that I didn't eat into, on top of my 500 deficit from food. I figured that gave more wriggle room if there was accuracy in the "earned" bit or the calories consumed!

Also you have to adjust down you weight on the device, as you'll burn less carrying less!

Mellor wrote: »

Say I burn 2500 per day at rest. And today I went to the gym for an hour burning 320 cals lifting weights. For arguments sake, lets say both of those numbers are perfectly accurate.
Most people would add them together and assume I burned 2820. But that's forgetting I'd still have burned 120 or so had I sat on my ass instead. Which is counted for in the 2500. The real exercise expenditure is what I burn in excess of that, so 200 cals or 2700 total.

Is that true of all devices? I have an old garmin (310xt) and a newer garmin (920xt), and the 920xt will give significantly lower calories burned than the old device for the same activity (with the same heart rate zones, weight, age, gps/ distance etc on both)? I still lost weight with the old device though to be fair.

Both are lower if I put a run or a cycle into myfitnesspal for an estimate, or what the likes of strava will estimate. And they're proportionately more off for walking than more intense activities!

Mellor

Macy0161 wrote: »

Is that true of all devices?

Pretty much. Whether they are wrist devices, chest straps etc.
They measure heartrate/cadence/GPS or whatever. And input those numbers into their algorithm to come up with a number. The algorithms are changed and updated over time. Which might explain the change with the newer model.
To measure actual energy used you need to be hooked up to device that measured respiration.