MFP has a calorie floor. Fitbit doesn't. Who to believe?

JazzAmbassador · January 2015

I've done a bit of searching here, but haven't seen this exact issue addressed. I use MFP in conjunction with Fitbit (like a lot of us) and I've noticed that MFP seems to have a calorie "floor"; that is, once you input biodata, lifestyle, and weight loss goals, MFP calculates the number of calories you should stay under. That number may go up (with activity), but it never seems to be lower than the initial calculation. Fitbit, by contrast, even with the same data and goals, provides a calorie goal that doesn't seem to have any floor, so that inactivity results in a lower calorie allowance than MFP.

An example here might help. MFP allows me 2120 calories/day in my quest to lose half a pound a week. Last Sunday I was a binge-watching couch potato. MFP did not import any extra calorie allowance from Fitbit, but ruled that my calorie intake of 1973 calories was under my goal of 2120. Fitbit, by contrast, decided that my lazy butt only deserved 1845 calories that day, and so I'd gone over.

Maybe this doesn't matter that much; I've been using MFP's more generous allowance so far, and have still lost 20 pounds in the last 6 months. But I'm curious to know what others make of this and do. Thanks in advance.

StaciMarie1974 · January 2015

MFP assumes you were accurate in your stated activity level. Fitbit does not take your word for it, it bases on your actual calorie level. You can turn on negative calorie adjustments and both sites will get the same result. MFP does not use the negative calorie adjustment by default. (NCA means if your tracker says you were less active than MFP expects, MFP reduces your recommendation.)

Personally I would use my Fitbit to estimate where I'd be at the day's end, based on whether or not I was going to get in more activity. And either eat to meet my goal deficit, or move more to cover my intake. I never relied on MFP's goal strictly because I understood it was based on ME. So I had to live up to my end of the bargain for MFP to 'work' right.

JazzAmbassador · January 2015

That makes sense. If anything, I've low-balled myself on MFP, listing myself as sedentary with no activity (which was true that Sunday, but somewhat less true in general), and it still gave me that calorie allowance. So it's not so much me needing to be accurate as it seems to be MFP being too generous with their allowance for "sedentary" calories. Guess I need to start paying more attention to Fitbit's numbers.

TheVirgoddess · January 2015

Enable negative adjustments. That will adjust your calories just like they are adjusted on FitBit.

JazzAmbassador · January 2015

AHA! Never noticed that option (obviously). Thank you, Virgoddess! Let's see what that does. Of course, there's still the weird inequities in how each program projects calories; right now, for example, I'm about halfway to my 10,000 steps; MFP and Fitbit are both allowing me "extra" calories, but MFP says my daily calorie goals set is about 300 calories higher than Fitbit's. Still, allowing negative calories should fix the original issue I raised, so thanks again!

JazzAmbassador · January 2015

Okay, so here's a related issue -- seemed silly to start a new thread:

It's 10 pm. I'm done eating, done drinking, and done moving; I'm in bed and about to turn out the lights.

MFP says I can still eat 809 calories, 520 of which are "earned" calories from Fitbit. That number has been static for a while.

Fitbit, meanwhile, says I can still consume 505 calories. But 5 minutes ago that number was 497 calories. Five minutes before that, it was 502; 10 minutes before that, it was 511. All that while lying still in bed.

I know from experience that, when I sync for the first time tomorrow, that 809 "underage" on MFP is going to shrink to a much smaller number; I can't even begin to guess where Fitbit's count will be in 5 minutes, let alone at midnight.

So what's maddening to me is that, at any given moment, each app is providing a number of "calories left to eat" whose relationship to reality is a mystery. I want to use these apps in part to answer some variation of the question, "can I eat anything else today?" (e.g., "can I have that cookie? Or another glass of wine?"). But the answer the apps themselves give simply can't be trusted. Is anyone else bothered by this and -- more importantly -- found a way around it?

ana3067 · January 2015

If you are on average fairly consistent with your activity levels, it doesn't matter when you have a day or two out of the ordinary. I can have a really active high-walking day (pair that with a heavy school backpack with way too much stuff in it) or I can sit on my *kitten* watching TV. it all balances out over time.

Pick a calculator whose numbers are consistently more accurate for your goals and stick with it. If the number FitBit gives you tends to be too little on average then use MFP. If MFP is too high, use FitBit. Or just decide that you want to eat more/less when needed. This is something that you shouldn't be taking too seriously in the sense of trying to be 100% in control of everything, because you can't. I just realized that these past few days, whcih is why I'm now ditching my more regimented approach to tracking but still using the same static goal every day based on average actvity levels.

WalkingAlong · January 2015

JazzAmbassador wrote: »

Is anyone else bothered by this and -- more importantly -- found a way around it?

I never understood the Fitbit "moving target" idea. I would suggest you either forget the daily estimates/calories and focus on the chart in your profile, of 30 day average intake vs. burn. Keep those lines 500-750 calories apart. I lost my weight that way.
Or
Use yesterday's burn level to guide today's eating, based on the data from either app. If you were allowed 2000 calories yesterday, eat that today. At least it's a fixed value. Tomorrow eat from today's totals.

JazzAmbassador · January 2015

Good advice all, thanks.

MFP has a calorie floor. Fitbit doesn't. Who to believe?

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