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Sudden Drastic Change in Calories Burned Estimation

Former Member over 10 years ago

I've just recently started having a problem with the calorie estimations.

I am a 5'5'', 120lbs. female.

Prior to December, I was consistently averaging about 525 calories burned for a 6 mile run (10km), for about 11 months.

Then one day in late November I got a reading for 320 for a 6 mile run. I thought this was strange, but wrote it off as an anomaly. However, even since then, I have been consistently averaging 320 calories burned for a 6 mile run.

I changed nothing in the settings. The only thing I can think of is I changed the battery in the HRM around that time. I do wear a heart rate monitor strap each time. Could this be an issue with the HRM or with the watch itself? My average HR readings seem to be the same.

What the heck?? There is no way that almost an hour of running (lots of hills usually) burns only 300 calories now!!

0 JSRUNNER_ over 10 years ago

If the HRM is giving you similar figures then I can't see that being the cause of the issue. Did you do a reset on the watch at the point you changed the HRM battery - that does seem to be a problem for users where they do a reset on the watch. Has your TE for the run changed too - I would expect this figures to have some sort of correlation?

0 Former Member over 10 years ago

My average heart rate readings have gone down by about 10 points. I used to average about 165 before and now I average about 155. I do not feel like I am working any less hard than I was before. If anything, I am pushing myself harder because I am disheartened by these ridiculously lowered calorie counts.

I did not reset my watch at the time of HRM battery change.

I do not know what my TE is because my watch does not track this. I have a forerunner 110.

It just doesn't make sense for my caloric expenditure to drop so drastically OVER NIGHT. In fact, it seems to be decreasing with every workout. At this rate, sitting on the couch for an hour will burn as many calories as an hour's worth of running!

All of the research I've done indicates that you burn .75 calories x your weight (in lbs.) per mile, GROSS, and .63 calories x your weight (in lbs.) per mile, NET.

So, for a 6 miles run my gross calories burned should = ~540 and my net calories burned should = ~482.

Those number are consistent with the numbers the watch and HRM were giving me for the first 11 months. There is no way I'm only burning ~320 GROSS calories on a 6 mile run now.

0 JSRUNNER_ over 10 years ago

Ah! If your heart rate reading has gone down then that would definitely affect the calorie calculation. If the drop occurred exactly at the point you changed the battery then I would take it out and refit again including making sure all the contacts are clean. If that leaves you on the same lower heart rate then try another new battery.

If that fails then you may need to look at a new hrm/strap. Mine became unreliable after about 12 months but tended to read too high and was giving me an average of 230 for some runs (I know my max is about 185).

I've had the new strap (fabric with a grey band) for about two years now and it is much more reliable and consistent than the original and still on the same batteries despite being used about 5 hours a week.

0 3950647 over 1 year ago

Same has happened to me. I’ve done a reset on my computer and uploaded data to connect. Not helped. Baffled and annoyed too! I hear ya!

0 3950647 over 1 year ago

Same happened to me. Exactly! Garmin help said to upload data on computer to connect app as was also getting storage data full message. It hasn’t worked. Baffled and annoyed!