heybales wrote: »

Section Two - More Details

Why should I manual log a workout?
For non-HR devices, the calorie burn for movement is totally based on steps and distance seen and your weight.
This can actually be very accurate, more than HRM if flat and distance is correct.
Your device does dynamically adjust stride length as you walk, but it is based on the set stride length and your weight, which gives an expected impact on each step. The amount of actual impact compared to that figure results in a stride length that is actually used right then.
So dynamic stride length and time = pace and weight = calories burned.
Different formulas for walking and running lead to that accuracy, and are only valid for walking and running flat, since the device has no idea of incline, or even carrying extra weight (which would effect impact seen) for that matter.
So other exercise that is not step based, would not be valid calorie burn based on those formulas, and that's assuming all the non-"steps" are even seen, which they probably aren't. Like biking or elliptical.
Some exercises don't even have steps for all the hard effort, like rowing, lifting, swimming, yoga, pilates.

For HR devices, calorie burn for daily activity is still step based as that is more accurate, but for exercise it's based on HR formula. HR formula is used when you start an activity record with button press, and your steps are high enough to indicate the higher HR is indeed from exercise, or HR and steps go up to show exercise is being done. Otherwise it thinks elevated HR due to something else and just uses step calculation.

HR formula is only a decent calorie estimate when the exercise is steady-state aerobic, same HR for 2-4 min. Anything anaerobic, like good lifting or interval workout, which is also non-steady-state HR, is not valid use of formula and will result in inflated calorie burn. Step based would actually be best for intervals.

So lifting should be manually logged with either device type.
MFP has Strength training for 5-15 reps and sets and rests of 2-4 min, Circuit training for 15 plus reps and rests of 1 min or less and several circuits, Calisthenics for body weight usually over 20 reps and brief rests. Fitbit has Weights, Circuit Training, Calisthenics to match.

Reasons for Fitbit estimating better calorie burn on manual logging than MFP.
Mainly applies for non-HR devices, or if HR seen is not accurate.
MFP and Fitbit and many other sites use the same METS database that is publicly available. Results of database for activities are given as a multiplier of your resting metabolism - 1 MET.

For MFP to use it based on your weight, they use a common assumed conversion (1 MET = 1 cal/kg/hr). But it can be clearly seen that 2 people with the same weight can have very different resting metabolism (RMR), so those assumptions can have some inaccuracy. A young muscular goal weight male could have the same weight as an older overweight female. Guess who's MET calorie burn is actually higher? Guess who receives inflated calorie burn using MFP's database? Yes, MFP could indeed improve this, but that's why they sync with activity trackers now. Same as Fitbit won't improve their food log because just easier to sync with MFP and others for that.

So Fitbit leaves the database at METS, and actually uses the calculated BMR they use for all non-moving calorie burn, as the basis for exercise calorie burn.
Their database also has some exercises with more options for intensity, like swimming or biking based on actual speed, or elliptical and spinning with choices of intensity, at least giving a chance to get better accuracy.
So yes you could manually log either place, especially if you have a more accurate calorie burn anyway, but Fitbit is better if using the database entry.
To inform your friends that you are indeed working out, just make a wall posting about the workout, including more useful info than 1 line would provide. More inspiring that way too I think.

Why does MFP have a different eating goal than Fitbit's?
So even if you have both sites setup for same 500 cal deficit say, they will not match for eating goal until the day is finished. While the day is progressing, they use different methods, more on that later.
Recommend don't follow 2 roads to same destination, use MFP for food and eating goals, use Fitbit for daily movement goals and exercise logging.

How does the Fitbit calorie adjustment work?

How it works will allow seeing why the differences occur too. But have to understand the basics first.
Laying out some numbers to use for pretend person in below math.
BMR : 1600
Sedentary on MFP gives daily non-exercise calorie burn : 2000
Deficit for 1 lb weekly loss : 500
Eating goal on non-exercise days : 2000 - 500 = 1500

What happens without Fitbit data at end of day.
Log 300 calorie burn exercise.
Daily burn 2000 + 300 exercise = 2300 total estimated daily burn
2300 - 500 deficit = 1800 eating goal
MFP keeps it simple by just adding the exercise to eating goal though.
1500 + 300 = 1800 eating goal. Same 500 cal deficit.

So that activity level may or may not be true, MFP is going to use Fitbit data to correct it, here's how at end of day again.
Fitbit reports daily 2500 calorie burn, perhaps that includes a manually logged workout in it, or that's what it saw anyway so no logging needed.
Fitbit 2500 - 2000 MFP estimate = 500 calorie positive adjustment.
Eating goal 1500 + 500 = 2000 new eating goal. Same 500 cal deficit.

Say you log that 300 cal workout on MFP so it knows about it. And it matches what Fitbit thought you burned anyway, so overwrite on Fitbit causes no change in data.
Fitbit 2500 - 2000 MFP - 300 exercise = 200 cal adjustment.
Eating 1500 + 300 exercise + 200 adj = 2000 new eating goal. Same 500 cal deficit.

Say Fitbit said your daily burn was 2600 prior to manually logging, then after manual logging 300 cal workout it went down to 2500. That means it estimated 400 cal for that workout, but you replaced the calorie burn. Logging the workout in Fitbit or MFP would be the same effect.

So what happens when you have big adjustments but no exercise done?
It means your actual activity is higher than you selected in MFP. If you can still meet your eating goal daily with big adjustments, that's fine.
Otherwise it might be wiser to increase activity level to reduce adjustments, because better planning leads to better success, in most cases.

So what happens when you have smaller adjustments than what the exercise did burn?
It means either your activity level is lower than you selected, or your body is doing the first thing it does when undereating by too much - it makes you move less.
Fitbit tries to help with that effect by having the step goals, to try to keep you moving. Sadly, if the body can't adapt by moving you less, it'll slow you down in other ways to still compensate.
But you may easily see that you have a hard 800 calorie burn workout, but then move around a whole lot less in the evening, leading to an adjustment that is only 700 calories.

So Fitbit 2700 - 2000 MFP = 700 cal adjustment.
Eating goal 1500 + 700 = 2200 new eating goal. Same 500 cal deficit.
If you manually logged that in MFP so you could see it, and it matched what Fitbit saw already, you'd get:
Fitbit 2700 - 2000 MFP - 800 exercise = - 100 cal adjustment. That's negative.
Eating 1500 + 800 exercise - 100 adj = 2200 new goal. Same 500 cal deficit.

Isn't that wonderful the way it works! Helps you to always eat less than you burn. And if you picked a reasonable weekly weight loss goal, you'll always have the same deficit no matter what.

Perhaps you do best with a single daily eating goal though no matter the daily activity which is pretty consistent week to week, so you want to use Weekly average TDEE deficit method.
You need to confirm you are manually logging on Fitbit whatever workouts you should be.
You need to unsync accounts so your manually set eating goal doesn't change.
You need to look at your weekly Fitbit report under Total Cals Burned - Daily Average. Take that x 0.8 for 20% off or x 0.85 for 15% off, ect, and set that new figure as your eating goal, reached every day.
Just adjust as needed if the TDEE changes enough. Your MFP activity level, weight loss goal, ect, don't matter now. But neither will the math that MFP does, because it isn't aware you are doing exercise. Which if you log workouts on MFP too, it must be done as 1 cal, but better just to make a wall post about it anyway.

What happens to those Fitbit calorie adjustments during the day?
Same pretend person as above, but using 3 pm as sync time, or 15:00 hrs, which is 62.5% of the day (15/24), meaning 37.5% is left.

MFP estimated daily burn 2000 x 0.375 = 750 more calories to the day.
Whatever Fitbit reports for the calorie burn up to that point, 750 is added on for Full Day Projection.
Let's say no workout yet, Fitbit reports 1375 burned.
Fitbit 1375 + 750 MFP rest of day = 2125 projected.
Fitbit 2125 - 2000 MFP estimated = 125 cal adjustment so far at 3 pm.

Let's say you did that 300 cal workout 2 - 3 pm and sync right then.
Fitbit 1675 + 750 MFP = 2425 projected
Fitbit 2425 - 2000 MFP = 425 cal adjustment.

So any exercise done early in the day does NOT cause inflated for rest of the day. Rest of the day is based on the activity level you selected in MFP.
This would be a case for seeing if your whole evening is pretty sedentary after work, then setting MFP to Sedentary even though rest of the day is say Lightly active or more, might make sense. Just depends on what you find out the morning after the day has completed. If you met the last eating goal you saw before going to bed, but the morning says you went over by 100 calories or more, then going down an activity level might be good.

Now, there is a twist to this depending on how often you sync, and that is what Fitbit reports to MFP. Fitbit has 2 options for calculating your per min burn until you sync device and it has real stats to look at.

Sedentary or Personalized under Log - Food - Food Plan section - settings icon, some older accounts also call this Calorie Estimation under View Settings - Settings.

Sedentary means Fitbit is estimating a per minute calorie burn barely above BMR and much less than MFP's Sedentary setting, and until a sync gives updated stats, that's what it reports to MFP.
So if you don't sync until late in the day, Fitbit could be reporting to MFP very underestimated calorie burn and you'd see negative calorie adjustments, until you finally synced and possibly got a big surprise you might have problems meeting as an eating goal.
If you sync often it wouldn't matter as much, as each new device sync causes a new sync with MFP with that new data. Or at least sync before final meals.

Personalized means Fitbit is estimating a per minute calorie burn based on historical daily data (week and weekend different), and until a device sync that gives updated stats, that's what is reported to MFP. If each day is close that's not so bad, and if you sync at end of day, there wouldn't be as much of a difference. Calorie adjustments would slowly increase but not jump after a workout that you didn't sync yet, but by end of day it would be in there if it was normally done.
Again, if you sync often it doesn't matter.

Fitbit syncs to MFP after daily calorie burn goes up by 100, or a device sync or change of stats that it syncs over.
So if Fitbit is set at Sedentary, it should take longer than 1 hr to sync new daily burn to MFP, if set to Personalized, it should be under 1 hr. Or quicker if device syncs or manually logged workout.
[Thanks for posting all of this. I am looking forward to seeing how all of this works together]