Figuring TDEE based on data, rather than on calculators

emilysusana

I’ve been logging for 9 weeks, every day without fail. I use a food scale, wear a Fitbit, and get most of my exercise calories from walking and running. I’m not too worried about accuracy for my intake, as I’m fully steeped in the “weigh everything, guesstimate nothing” doctrine—I’ve lost before on MFP with success (didn’t sustain it because of my approach to maintenance).

What’s new this time is the Fitbit. I’ve only been eating back roughly half of my exercise calories because the numbers of calories on my Fitbit adjustment me seemed astonishingly high. I have my activity level set to sedentary even though I’m not, because I like to see my activity as a tangible bonus. When I did this before without a Fitbit, I logged my runs and purposeful walks manually, but there again had my activity level set to sedentary.

Now that I have about 9 weeks of data, I’d like to reevaluate my “eating back half” plan. What’s the best way to calculate how much I’m actually netting?

emilysusana

The numbers I have to work with are: my average intake (MFP), my average daily burn (from Fitbit), my weight loss based on moving average (Happy Scale)... these are the numbers I need, right? I should find out what my deficit has been based on weight lost and compare that to what the numbers say it has been? And see if I’ve been losing more quickly or more slowly than what the in/out calories say?

hypocacculus

There is no way to determine exactly what calories you are using in reality without the aid of a bunch of technicians and a laboratory; The same goes for weight loss - you cannot know what proportion of your loss was fat, water, or glycogen etc. without specialist equipment.

All of these calculators and gizmos help you to make decisions on what to eat and do, but are often very inaccurate. For example, is your fitbit giving you calories you burned doing exercise, or the calories burned doing exercise plus the calories you would have burnt anyway just by being alive? Because if it is the second, you are double counting with your base calorie allowance in MFP.

robertw486

You have all the right feedback, and the data to figure out what your actual average deficit is. Being weight loss isn't often linear it might help to review as you add data points to help solidify the long term average.

Actual loss over time should give you the deficit, and then you have that to compare to your Fitbit calories and where any error is. Since it sounds like you have food tracking down to the specifics, likely any error you find is going to be with the Fitbit calories. But some claim their Fitbit is very accurate for them, so maybe you'll get lucky and the numbers will be on track with expected weight loss.

lemurcat2

Just calculate total calories consumed over that period and then add 3500 for each lb lost, and divide by the number of days. That's your TDEE based on your current activity level.

To determine if you should be eating more than your 1/2 of exercise calories, have you been sticking to your goal? Doing so, did you lose more, less, or the same as planned?

tinkerbellang83

emilysusana wrote: »

I’ve been logging for 9 weeks, every day without fail. I use a food scale, wear a Fitbit, and get most of my exercise calories from walking and running. I’m not too worried about accuracy for my intake, as I’m fully steeped in the “weigh everything, guesstimate nothing” doctrine—I’ve lost before on MFP with success (didn’t sustain it because of my approach to maintenance).

What’s new this time is the Fitbit. I’ve only been eating back roughly half of my exercise calories because the numbers of calories on my Fitbit adjustment me seemed astonishingly high. I have my activity level set to sedentary even though I’m not, because I like to see my activity as a tangible bonus. When I did this before without a Fitbit, I logged my runs and purposeful walks manually, but there again had my activity level set to sedentary.

Now that I have about 9 weeks of data, I’d like to reevaluate my “eating back half” plan. What’s the best way to calculate how much I’m actually netting?

What is your average rate of loss during the 9 weeks? Your trending rate of loss will tell you more about what you're burning than anything else. It's pretty much maths.

If you want to see this info easily you could use a trendweight app like Libra or Happy Scale.

sijomial

Would suggest just using last four week's data to get your recent levels, you don't need to use your output (activity & exercise) estimates or your Fitbit numbers at all.

Add up all your food calories eaten for last 4 weeks, add 3500 for each pound lost in that time, divide the sum by 28 - that's your TDEE.
(You could do 8 weeks and divide by 56 if you want but I'd exclude the first week when loses can often be out of proportion to your deficit (water & food weight).

By the way "activity level set to sedentary even though I’m not" is why you are getting a large adjustment.

emilysusana

lemurcat2 wrote: »

Just calculate total calories consumed over that period and then add 3500 for each lb lost, and divide by the number of days. That's your TDEE based on your current activity level.

To determine if you should be eating more than your 1/2 of exercise calories, have you been sticking to your goal? Doing so, did you lose more, less, or the same as planned?

Thanks everyone. I did what lemurcat2 and sijomial suggested and calculated my TDEE as 2200. It looks like my Fitbit calories are right on the mark, actually, because Fitbit says I burn around 1400-1500 most days, and I’ve been losing 1.5/week.

Good to know, I could eat about 250 more calories a day and still lose a pound a week. I’ll do that soon once I get myself out of the overweight range! Right now everything feels good so I’ll go with it!