TDEE/BMR questions about accuracy and stuff

eunialy

For calculating BMR/TDEE for someone with 40% or higher body fat, which formula would be the best?

I was eating around 500 below BMR (my BMR is around 2000 for 5"8, 250lb) for a few days before I realized I got BMR and TDEE mixed up. I'm trying to get a good idea of what my TDEE should be now for a more accurate number on daily calorie intake to lose weight, but using something like the IIFYM TDEE calculator, the BMR/TDEE values vary a lot depending on the formulas.

For example, under Katch-McCardle my BMR and TDEE for moderate activity is 1843/2695, compared to Harris-Benedict which says 2351/3438. Not really sure which one I should go by honestly.

Also, if the only goal was weight loss (just theoretical), what would be the difference between exercising more and eating more, to exercising less/not at all and eating less? It seems like I'd just end up with a skinnyfat body and lose weight at the same pace if it follows calories in/calories out. If it worked in that way, would there be any issue with calculating TDEE at sedentary levels, then eating -20% of that while still working out moderately?

Thanks!

Fitteacherc

BTW, this is the best thread about BMR/TDEE I've ever seen: http://community.myfitnesspal.com/en/discussion/931670/bmr-and-tdee-explained-for-those-needing-a-guide/p1

I'm in a similar boat as you. At the end of the day, I think that your diet is the most important factor in changing your body. Some people think that they can exercise their way out of their diet choices. I think you should experiment and figure out what works for you - some people like to eat a smaller deficit and work out more and some eat a large deficit and work out less.

Instead of selecting an activity level, it might be better for you to use the "sedentary" number, log your food/exercise, and then eat back half of your exercise calories (the post I linked above explains that method).

ana3067

HB calculation is generally considered to over-estimate, especially for over-weight/obese. Mifflin St-Jeor or KA are better calculations. I just did a quick estimation and got around 2500/3200 based on using body fat % or height.

Because these numbers are so different, I would recommend eating the larger one, assuming body composition is important to you. Subtract 20%, set that as your goal. If you calculated your needs with exercise in mind, then you are eating TDEE and do not need to log and eat back exercise calories. If you did not include exercise then you need to log and eat back exercise calories.

So go with the 3400 (around 2700 at a deficit) and monitor your weight for 1-2 months. If you've not lost ~4lbs/month then lower it a bit (if you saw no weight loss, or almost none, I'd say lower to 2500, otherwise 100 cals is fine) and monitor another month. Keep doing this until you are losing consistently. The reason I recommend a month is because sometimes you don't lose on the scale for a week or two, but then when you average it all out over the month you are losing. I'm actually probably going to increase my calories a bit if the weihgt lost for the last 4 weeks is more than 4lbs, at this point it's about 3.2 for the last 3 weeks. So it's all about monitoring and adjusting as necessary. It's better to start with the highest number so you can easily lower it as opposed to starting too low and having nowhere to go with it.

As for your last hypothetical... there is no difference. Strength training will be ideal for body composition, but working out vs not working out will not change whether you do or don't lose weight. Protein intake is probably more important than strength training even. If you want to calculate a sedentary TDEE and subtract 20%, then you need to be doing so because you do not exercise. If you want to calculate your minimum needs without exercise included, as MFP defaults to, then you can go ahead and calculate that and then log and eat back exercise calories.

yarwell

eunialy wrote: »

For calculating BMR/TDEE for someone with 40% or higher body fat, which formula would be the best?

Katch McArdle - a man with 40% body fat would probably be an outlier in the studies that produce the regression equations. At 38 BMI body fat on a man isn't usually as high as 40% - did you have it measured ? The difference between a more typical 34% and 40% is only ~100 calories on K-M.

I think you can safely say your TDEE is well over 2000 and with that much fat in stock you can run a higher deficit for several weeks. I would shoot for somewhere around 1600. Why dawdle around.

If fat loss is the only goal you would retain a bit more lean mass making part of your deficit with exercise but that's perhaps something to worry about when you get to overweight.