Is this math correct?

KnitSewSpin

I've been serious about counting calories and weighing/measuring my food for three weeks (this time anyway).

I've lost 6.8 lbs in 21 days
I've eaten 1,200 calls every day

In 21 days:
25,200 calls eaten
23,800 deficit (3,500 x 6.8)
49,000 divided by 21 is 2,300
2,300 is my TDEE

Is that right or am I doing this wrong?

KnitSewSpin

2,300 btw is exactly the number my Fitbit gives me. It is spot on.

KnitSewSpin

And I'm planning on eating more than 1200 cals so don't yell at me. Just did it for three weeks because I'm feeling motivated.

mom22dogs

Unless I'm reading your figures wrong, you're figuring a 3500 cal deficit per DAY? That's not right. To get 1 lb a week off, it's 3500 a week, or 500 cals per day. so 500 cal x 21 days is 10,500. Unless I just totally don't understand how you're figuring.

KnitSewSpin

No not per day. I calculated my deficit by multiplying lbs lost by 3500.

Nicklebee93

TDEE is BMI plus your activity level. BMI is what your body burns if you literally did nothing all day. So TDEE is BMI calories + activity level. So your TDEE might be right at 2,300 calories but your math is off.

It's 3,500 deficit per week to lose 1 pound.

mom22dogs

n1cholee93 wrote: »

TDEE is BMI plus your activity level. BMI is what your body burns if you literally did nothing all day. So TDEE is BMI calories + activity level. So your TDEE might be right at 2,300 calories but your math is off.

It's 3,500 deficit per week to lose 1 pound.

Yes, OP, you figured the 3500 deficit every day, which isn't possible. It should be per week. (and it's BMR is what your body burns if you do nothing all day, but you probably meant to say BMR and not BMI.)

KnitSewSpin

I figured the deficit by pounds lost in that period. I know I can't lose a lb a day.

jwschutz

I think your math is right
In 21 days:
25,200 calls eaten / 21 = 1200 Cal/day
23,800 deficit (3,500 x 6.8) / 21 = 1133 cal/day
49,000 divided by 21 is 2,300 or 1200+1133 = 2333 cal /day
2,300 is my TDEE

KnitSewSpin

Thanks jwschutz

sijomial

KnitSewSpin wrote: »

No not per day. I calculated my deficit by multiplying lbs lost by 3500.

Reasonable assumption but not just yet......
Your numbers will be skewed at first as a lot of the initial weight loss is water and not fat.
Smaller effect from smaller amount of food inside you as well.
So it's doubtful that you lost 6.8lbs of purely fat.

Hormonal fluctuations need to be accounted for as well.

Basically disregard your first month and then compare month on month to see your true deficit.

KnitSewSpin

That is reasonable and I've thought of that too. I will definitely check in with my numbers every few weeks to reassess.

Clawsal

With people saying you are wrong, I just did the math again:

21 days x 1200 calories eaten per day = 25 200 calories eaten
total pounds lost: 6.8 lbs
assuming it was only fat (doubtful) and that 1 pound of fat equals 3 500 calories
23 800 deficit

Total calories burned: 49 000
per day: 2333 calories, which yes, is your TDEE.

So your calculations are absolutely right and good job on losing the weight! Also, since I also have a fitbit I am happy to hear it is accurate.

I think you have also lost water weight (start of the diet) so your TDEE is probably a bit lower. I would love to hear from you in three weeks see if the numbers stay the same.

peacemongernc

I'm SO happy to see other calorie math doers out there! I feel like such a geek when I start doing those calculations. A couple of years ago when I was just using the desk top version of MFP, I spent more than an hour adding up, one day at a time, 6 months of my numbers to figure out my TDEE. The math has kept me sane when I've hit plateaus that have lasted as much as 10 weeks at a time, while eating a deficit the whole time. In the end, if I'm careful with my logging (meaning it isn't November or December, lol!) I end up within a few oz of where I think I should be once I have my weight loss "whoosh". I took all my numbers and compared them to what I got from a Bod Pod assessment and figured out that my metabolism fairly consistently about 5% more efficient than "normal", or I'm always about 5% off, but it gives me a reasonable place to start. I use 1835 as my TDEE, but the Bod Pod gave me 1925. I just go with the 1835, and the math works out.

Anyway, my only point is, your math looks good and I'm glad to see some folks similar to me out there.

peacemongernc

Clawsal wrote: »

With people saying you are wrong, I just did the math again:

21 days x 1200 calories eaten per day = 25 200 calories eaten
total pounds lost: 6.8 lbs
assuming it was only fat (doubtful) and that 1 pound of fat equals 3 500 calories
23 800 deficit

3500 calories is a pound of FAT? I hadn't heard that... I just assumed a pound of weight, but that makes sense. So how many calories is a pound of muscle?

If I'm losing about 75% of my weight as fat, but 25% as muscle (which seems to be how it is going), that might account for the difference I am finding between my calculations and those of the Bod Pod. So maybe I'm NOT 5% more efficient that I thought... maybe it's the difference in the composition of my weight loss.

Interesting.

BurnWithBarn2015

Your math is right on.

i did it this way and lost 130 lbs in 400 days......but @sijomial is right too. It will change.
closer to goal i had more fluctuations...the slow down and hormonal bloating etc.

Still i kept and doing all my data and it is almost spot on with my Misfit ( same as a Fitbit but water proof and a much cheaper device)

sijomial

peacemongernc wrote: »

Clawsal wrote: »

With people saying you are wrong, I just did the math again:

21 days x 1200 calories eaten per day = 25 200 calories eaten
total pounds lost: 6.8 lbs
assuming it was only fat (doubtful) and that 1 pound of fat equals 3 500 calories
23 800 deficit

3500 calories is a pound of FAT? I hadn't heard that... I just assumed a pound of weight, but that makes sense. So how many calories is a pound of muscle?

If I'm losing about 75% of my weight as fat, but 25% as muscle (which seems to be how it is going), that might account for the difference I am finding between my calculations and those of the Bod Pod. So maybe I'm NOT 5% more efficient that I thought... maybe it's the difference in the composition of my weight loss.

Interesting.

@peacemongernc
I believe that metabolising body protein is roughly a fifth of the amount of calories compared to metabolising body fat.
Start lifting to minimise loss of muscle!

Clawsal

peacemongernc wrote: »

Clawsal wrote: »

With people saying you are wrong, I just did the math again:

21 days x 1200 calories eaten per day = 25 200 calories eaten
total pounds lost: 6.8 lbs
assuming it was only fat (doubtful) and that 1 pound of fat equals 3 500 calories
23 800 deficit

3500 calories is a pound of FAT? I hadn't heard that... I just assumed a pound of weight, but that makes sense. So how many calories is a pound of muscle?

If I'm losing about 75% of my weight as fat, but 25% as muscle (which seems to be how it is going), that might account for the difference I am finding between my calculations and those of the Bod Pod. So maybe I'm NOT 5% more efficient that I thought... maybe it's the difference in the composition of my weight loss.

Interesting.

Well this 3500 number has been kind of floating around for a while but it is just an estimation. It does refer to adipose tissue, which is constituted mainly of fat (9 cal per gram - 4086 calories per pound).

What I meant was... it requires approximately a 0 calorie deficit to lose 1 pound of water and for 1 pound of muscle I am not sure of the number but it is certainly lower than 3500 calories.