Oversimplifying TDEE

stryker520 · February 2019

If you plug your age and height and DESIRED goal weight into a TDEE calculator theoretically, so long as you stay at or under that caloric number, won't you achieve that goal weight (eventually)? I guess the only thing that is missing is how long it would take with this methodology. I am sure it is more complex than this but someone will have to explain to me how/why because this just seems like straight logic to me.

janejellyroll · February 2019

If the estimates for your TDEE is correct, yes.

There are people who have success basically eating for the "goal weight." I have heard, just anecdotally, that this will take longer but I don't know anything more specific than that.

Tacklewasher · February 2019

It may take a long time.

I punched in some numbers for me.
To maintain at my goal weight and just sedentary (I'm ignoring exercise for now) it gives me 2185 cals
To maintain at my current weight (30 lbs more) it gives me 2340

So if I eat 2185, I'd be in a deficit of 155 cals. That's a weekly deficit of 1,085. That would give a weekly loss of .31 lbs. So it would take 97 weeks (just shy of 2 years) to lose the 30 lbs.

But it would take even longer than that. As every pound I lost would lower my then maintenance number, which would lower the deficit which would make the process take longer.

I've no idea the math to show how long it would take.

steveko89 · February 2019

I had some issues successfully using the MFP math when it came to exercise calories so I switched to more of a Target = TDEE - deficit strategy and feel like I have better process control with fewer variables at play.

Theoretically, eating for your goal TDEE should work, assuming your goal weight and TDEE estimation are appropriate. Overall, this is likely going to take longer than following the suggested deficit guidelines would. The difference between my TDEE at current weight (175lbs) vs. +50lbs is only about 300 calories, and only get smaller as weight is lost.

commonly suggested loss rates poached from another thread:
If you have 75+ lbs to lose 2 lbs/week is ideal (-1000 calories/day)
If you have 40-75 lbs to lose 1.5 lbs/week is ideal (-750)
If you have 25-40 lbs to lose 1 lb/week is ideal (-500)
If you have 15-25 lbs to lose 0.5 to 1.0 lb/week is ideal (-250 to -500)
If you have less than 15 lbs to lose 0.5 lb/week is ideal (-250)

By following the process you suggested, by the time you get to 15lbs over goal weight, you could easily have a deficit <100 cal/day which will make those last few lbs come off very slowly.

stryker520 · February 2019

Thanks for the input. This makes sense. In theory the logic is correct but the duration would be exhausting; especially as you get closer to goal weight.

cmriverside · February 2019

I think - pick one way or the other. Stick with it till it doesn't work any more. Keep good records. With knowledge comes power.

I lost my first 30-40 pounds at a pretty low calorie goal. I was obese when I started. Then I added 400 calories or so which put me at about 1600 (without exercise, I used MFP's method of eating more on exercise days.) It turns out (after ten years in Maintenance) that 1600 is way too low now at my goal weight - even though the calculators actually put me at 1500 to maintain. I maintain at 2000 PLUS exercise calories.

Keep good records. The calculators are just guessing. Your numbers will be your most valuable tool.

estherdragonbat · February 2019

Tacklewasher wrote: »

It may take a long time.

I punched in some numbers for me.
To maintain at my goal weight and just sedentary (I'm ignoring exercise for now) it gives me 2185 cals
To maintain at my current weight (30 lbs more) it gives me 2340

So if I eat 2185, I'd be in a deficit of 155 cals. That's a weekly deficit of 1,085. That would give a weekly loss of .31 lbs. So it would take 97 weeks (just shy of 2 years) to lose the 30 lbs.

But it would take even longer than that. As every pound I lost would lower my then maintenance number, which would lower the deficit which would make the process take longer.

I've no idea the math to show how long it would take.

And the other thing is that nobody consistently eats the same amount of calories every day. Even if we try, we know that the counts on labels are estimates, scales can start to fall out of calibration for a bit before we realize, "hey, that's got to be off".

That's why I get annoyed by those articles that say, "If you forgo one pat of butter on your toast every day, you'll drop 10lbs in a year." Because the reality is, it's like the "In five weeks you will weigh X" message when you close your diary. If I forgo that pat of butter? That's 40 calories. If I have a slightly-more-heaping than usual cup of shredded cheese topping my salad at lunch, I might get them back. Unless I ALWAYS eat exactly the same, to the gram and to the calorie... those little factoids are meaningless.

jelleigh · February 2019

I think this calculator would tell you how long it would take?

http://www.weightloss-calculator.net

ahoy_m8 · February 2019

stryker520 wrote: »

Thanks for the input. This makes sense. In theory the logic is correct but the duration would be exhausting; especially as you get closer to goal weight.

On the other hand, one MFP user grew exhausted with her deficit as she neared goal, so she just started eating at goal TDEE and stopped worrying about how long it would take. She felt better and it made maintenance an easy transition. It was a great strategy for her.

Oversimplifying TDEE

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