Calories Burned vs Food eaten

[craigfarrall]

Hi All,

I have had my FitBit Blaze for around a month now.

I just have a quick question that I am hoping somebody will help me answer. When I review the previous day's calories burned, if this is more than the number of calories eaten, does that mean you are likely to lose weight?

For example, on average my calories burned per day varies between 2,200 - 2,400 - therefore, if I ensure I eat no more than 2,100 calories per day, does that still mean I am likely to lose weight over a long period of time? Obviously the less I eat the more quickly I am likely to lose weight.

If you could let me know if this is correct and how accurate the calories burned is. I am using the MyFitnessPal app, so I am aware of the number of calories I am eating.

Thanks for your help.

[Dominique]

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@craigfarrall wrote:

When I review the previous day's calories burned, if this is more than the number of calories eaten, does that mean you are likely to lose weight?

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Yes, this is the idea: you need to eat less than you burn in order to lose weight. Not necessarily everyday, but at least on a weekly basis.

Note that neither estimating calories burned (what your Fitbit does), nor counting calories eaten (what you do with MFP) is exact science: there is a margin of error in both (see this article and this one). This is especially true if you have a very small deficit, as in your example (2100 vs. 2200-2400 calories). Your Fitbit may overestimate calories burned and you may underestimate calories eaten.  If you don’t get expected results in terms of weight loss after 2-3 weeks, make slight adjustments to your intake (eat slightly less) and/or your activity (move slightly more).

[craigfarrall]

Thanks for getting back to me.

I am aware that both the Fitbit and also the MFP aren't 100% accurate, which is understandable - but how accurate would you say the Fitbit calories burned is?

I understand the premise of weight loss, as I have lost a few KG's in the last couple of months, I was just wondering if the numbers of Fitbit were a fairly reliable number to take when looking for a maintenance number. I was previously eating around 1,600 calories per day during the weight loss, however I am looking for for more of a maintenance figure, so would you suggest eating around 2,200-2,400 per day for this, if on average that is what I have within my Fitbit app?

Thanks for your help as always.

[JohnRi]

If you want to maintain your weight, (I can't wait until I get to this problem in 6-8 months), you going to have to play it by ear a bit. 

What I mean if you eat 2100 calories, and you notice over a month or two, you lose a couple of pounds, then I'd increase to 2200.  Wait another month or two and see what happens.  You'll find your balance eventually.  Keep in mind as we get older, the amount of calories we burn goes down.  So keeping an eye on your weight and diet, well that never ends.

As for how accurate the Fitbit is, it's no where near 100%.  Is it 80% to 90%?  For many it is, other it's not.  I just treat it as it's in the ball park of correct.  But that leaves a lot of room for error. 

For you might be actually burning 2000 calories, you could be burning 2600 calories.  So give it time, and just monitor your weight and adjust as needed.

[GershonSurge]

I've carefully tracked calories eaten vs. weight change on both the Zip and the Surge. Based on a 3,500 calorie deficit per pound lost, the Surge is quite accurate for me over time -- say 30 days. The Zip measures about 20% fewer burned than what I actually burn. 

What's important is the numbers are consistant. To make it work, a person needs to accurately calorie count. This means checking labels and weighing portions. 

To maintain weight, I'd suggest eating the number of calories shown on the Surge or 20% fewer on a clip-on. Adjust if it's not working.

[Dominique]

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@craigfarrall wrote:

how accurate would you say the Fitbit calories burned is?

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I wouldn’t know, because I don’t count my total caloric intake (the only thing I count are proteins, and even that, only for the past four months). What I do know is that on very active days (more than 20k steps) I burn more (according to my Surge) than on low-activity days (5k steps). I use that to adjust my eating to some extent and the scale is the ultimate judge (I weigh myself daily). As you can see from my profile, my activity level varies quite a lot on a daily level:

I probably over-eat on low-activity days and under-eat on high-activity days. 

I’ve been losing weight at a very low pace, 1.5 kg (3.3 lbs) in three months:

That’s a 128 calorie calculated daily deficit. No way I could accurately plan this by counting calories and adjusting them to what my Surge tells me I burn!