Fitbit Adjustments Causing Confusion? Please Help!

A couple of questions. Do you have the same goal at Fitbit & MFP? Make sure you don't have one set to 2 pounds a week and the other set to 1 pound a week, for example. Also do not log step based activity, Fitbit will cover that.

MFP will only see Fitbit results after syncing your Fitbit. If you haven't synced in a while, MFP is going off your last sync.

Here is how I use them together:

Based on my activity level & stats MFP presently has me a goal of eating 1610 per day, which is for a 250/day deficit. MFP thinks I'll burn 1860 a day. Fitbit estimates my burn as of last sync, and if I'm ahead of schedule: MFP gives me extra calories. Right now MFP shows:

Goal 1610, Food Eaten 1636, Exercise 172, Net 1464, Remaining 146

This is because I'm on course to burn more than the 1860 MFP expects. Fitbit has similar #s but shows 193 calories left. It expects me to burn more in the last few hours of the day than MFP does. Its now almost 9pm. If I were to do nothing I'd burn another ~200 and be at 1979 burned less 250 deficit less 1636 eaten = 93 calories earned but not consumed.

The 'extra' # changes because both MFP & Fitbit estimate what you're going to burn and you may be more or less active in the rest of the day.

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What I suggest: Use Fitbit to get an idea of your daily total burn and set a goal for yourself. NO MATTER WHAT, hit that #. Subtract 600 (which is 500 for a 1 pound per loss rate and an additional 100 comfort since Fitbit is an estimate of your burn and may not be accurate) and eat about that. If you set your MFP to a 1 pound loss, it should balance out at the end of the day close to what Fitbit shows.

Ok so:

How fitbit works:
It tracks your activity over the day and estimates (based on what you've done) your daily calorie burn. Then syncs with MFP and "adjusts" your daily calories accordingly.

So the issue you may have are:
1. Go for a massive run in the morning, burn tons of calories

Fitbit would assume your daily activity would continue like this and estimate you calorie burn very high, giving you "too many" calories for the day. But as the day passes and fewer calories are burned it would continually adjust this till late in the day it would be completely correct.

2. You do nothing all morning (planning to work out at night) it would assume you're doing very little all day and restrict your caloric intake accordingly, so at midday you'd look at MFP and be like "WHERES ALL MY CALORIES?!", once you've gone done your exercise it would re-evaluate and assign you the correct values.

The most important thing to remember is that Fitbit calorie burn is an estimation for the rest of the day based on your activity up until the time you view it. So take it with a pinch of salt, if you know you're going to work out soon and it says you have few or no calories, disregard, eat and then work out, it will soon bump back up.

My reccomended settings are:
MFP: Activity level: Sedentary
MFP: Fitbit negative calorie adjustment: Enabled

Always use sedentary as activity level, then fitbit will add anything else on in due course, otherwise you;l be assigned too many calories and it will look like FItbit is trying to crush your soul by taking them all away lol Fitbit tracks activity level, so you don't need it on MFP, just use sedentary.

Best of luck!

Feel free to add me, I use Fitbit all the time and I'm still working out/losing

P.S whatever calories MFP says you have left after the Fitbit adjustment, you SHOULD be eating those back, otherwise you'll find yourself at a massive deficit, hungry and weak. I won't give you nonsense about starvation mode but eating below your "target" is not healthy or recommended as your "target" is already adjusted to lose weight.

I am a newbie with a fitbit and this is what I have found so far:

I want to lose 2lbs a week so have set both my fitbit and my MFP to this. So I need to have a daily calorie deficit of 1000 calories to lose 2 lbs a week. However, a 1000 calorie deficit takes me below 1200 calories based on my base sedentary TDEE. This is because of my age and the fact that I don't have that much to lose. It isn't recommended to eat less than 1200 calories.

This is where the problem comes in which affects the fitbit and MFP readings so bear with me while I explain this a bit further. So I know that if I am not more active and still eat 1200 calories then there is no way I will lose 2lbs a week as I won't have the 1000 calories deficit. The only way therefore that I can achieve a 1000 calorie deficit is through being more active.

This is where the crucial difference I have found between fitbit and MFP. MFP will not set your starting calorie goal to less than 1200 calories. Fitbit will.(nb If your starting sedentary calorie goal is not below 1200 you will not have a problem with the figures between MFP and fitbit.)

So my starting calorie goal on fitbit each day is 825 calories as my estimated TDEE is 1825 burn. My MFP calorie goal is 1200 calories. Clearly, it is not healthy to only eat 821 calories so I ensure I eat 1200 calories every day.

BUT when I earn more than my usual TDEE fitbit gives me more calories to add to my daily total. However, fitbit adds them to its starting point which is below 1200 calories ie today 821 calories. MFP adds the calories onto 1200 starting point and DOES NOT ensure there is a 1000 calorie deficit.

If we take yesterday as an example, fitbit said I burnt 2519 calories. I didn't do any exercise but I was more active than normal. So to have a 1000 calorie deficit according to fitbit I should eat 1519 calories. This is above 1200 calories, the deficit is not more than 1000 so is perfectly healthy.

However, as MFP starts my daily goal at 1200 calories it added on my activity calories to that and gave me 1898 calories goal. This means given my burn was 2519 I only have a 621 calorie deficit. If I eat what MFP states I am not keeping a 1000 calorie deficit and therefore will not lose 2lbs a week.

Also the info mcornall gave about how fitbit assumes you will be extra active all day if you have exercised in the morning is not what I have found. My fitbit always assumes I will be all day whatever I have set it to (in my case sedentary) and then adds on extra just for the period I have been more active. It does not readjust the whole day or it would be all over the place. This is why you set a 'base' for it to work from.

So what has worked for me to use fitbit - use fitbit for what it is saying you are burning each day and add in any specific exercises through MFP to get a realistic daily burn. Then ensure your calorie goal is at the deficit you want and is not less than 1200 calories.

The point mcarroll was saying in terms of 'exercise' calories being eaten back can misunderstood in terms of the fitbit. As long as the difference between your daily burn and intake is not more than 1000 calories and your calorie intake is above 1200 calories there is no reason you should feel weak or hungry. The whole eat back all your calories came from where people were setting their calorie goal to 1200 but their daily burn was 3000. This gave a deficit over 1000 calories which is not recommended.