Question about something Melkor said...

Hi Melkor and others,

On another thread where someone had little weight to lose, Melkor said:

And given that you'd need to run at most a calorie deficit of 500 cal/day with the relatively miniscule amount of body fat you have to lose... well, that's 6-8 weeks that Pilates will be enough, and 6-8 weeks to lose those last 6-8lbs.

My question is, I only have 5-7 pounds to lose - should I have a MAXIMUM of 500 calories a day deficit?  I've been trying to eat more on workout days, but I still have a bigger deficit than that...  and my losses have stalled. 

What's your current weight?  I'd guess if 5-7 lbs. is all you have to lose, then your 500 cal/week deficit is probably about the most you would want to lose.  Remember, we're all limited in how much fat we can lose based on the total amount of fat on our bodies.  If you're that close to your target weight, you may not have enough fat mass to support losing more than 1 lb./week...

There's a limit to how much energy you can get from fat in a day due to the limitations of the reaction speed of the lipase enzymes that work to mobilise fat stores for energy.

A limit on the maximum energy transfer rate from the human fat store in hypophagia is deduced from experimental data of underfed subjects maintaining moderate activity levels and is found to have a value of (290±25) kJ/kg d. A dietary restriction which exceeds the limited capability of the fat store to compensate for the energy deficiency results in an immediate decrease in the fat free mass (FFM).

S.S. Alpert Journal of Theoretical Biology Volume 233, Issue 1, 7 March 2005, Pages 1-13

Works out to about 31cal/lbs of fat mass/day, so if you don't have a lot to lose, even a 500cal deficit exceeds your body's capacity to mobilize fat stores and starts in on your muscle.

 For a not-completely-inaccurate guess at bodyfat you can use Covert Bailey's online body fat test - that one tracks an electrical impedance test to within 1-3%.   Don't push it to the edge of what's possible though, the margin of error is too large to take chances. 

I am a little bit confused, are you saying that happyteachers 500cal/day is too much? If so what is the solution?

Happyteacher are you at the end of a large weight loss goal, or do you just need to loose a 5-7lbs and your just starting?

Melkor, is Covert Bailey's really that accurate? It gives me 24% bf, while the bf function on my Tanita scale at home gives me 31%. Is Covert Bailey likely more accurate than a Tanita monitor? I'm trying to get a handle on my body fat percentage so I can adjust calorie intake accordingly.

I should probably just get some calipers.

 Are you sure you're using the right setting on your Tanita? There's an "athlete" setting there for people who exercise a lot and I think you're in that category - which should give you a considerably lower result.

 Also, keep in mind that the Tanita uses electrical impedance that passes through your lower body while Covert Bailey's test is mostly concerned with upper body measurements - it's entirely possible that you've got an uneven distribution of bodyfat and consequently a lower percentage in your top half.

 I would however trust the Tanita over Covert Bailey's test assuming you've used the correct setting for yourself - there is a larger uncertainty inherent in the measurements you use in Bailey's test.

 And yes - how much fat you can burn in a day depends entirely on how much you have. If you have a lot to lose, you can safely run higher deficits than the baseline recommendation, assuming you don't go beyond the "lose at most 1% of your bodyweight a week" rule. If you have only a few pounds left to lose the deficit you can have before it starts costing you muscle mass is very, very small in comparison.

  I don't recommend that you try to push things to the bleeding edge of what's possible based on the Covert Bailey test - or the Tanita one. The uncertainty in both methods is far too large. But I think it's nice to know that there's a reason why you should take it slower the closer you are to your goal, neh?

Thanks! I appreciate it.

I guess I haven't been looking in the right places for information...this is the first thing I've read that doesn't sound like a quasi voodoo one-size-fits all explanation!

Melkor, Am I following correctly that if I have 26% bf and weigh 135, my max deficit should be 1088? (31cal/lb fat/day x 35 lb fat = 1088 cal/day)  This would be whether the deficit is from exercise or just reduced caloric intake or both, yes?

That is a conservative number for me as my home scale and a hand held read 31.5% bf.  No great worries anyway because without greatly increasing my exercise, I don't get anywhere close.

Yup, sounds about right - for various reasons to do with maintaining lean mass, enzyme activity and getting your nutritional needs met I think that using your BMR as a practical lower limit on your calorie intake and aiming to get your calorie deficit mostly from activity has the greatest potential over the long run. For one thing, you get to eat more and don't run into the psycological issues around an overly restrictive diet.

 You can check with Phord's calculator : http://www.phord.com/cc to see your maximum safe and sustainable rate of loss - note that your maximum sustainable deficit will change as your weight does.  Due to the uncertainty inherent in most of the calculations - your BMR, your calorie intake, your activity level, your BF% are all reasonably accurate guesses rather than measured to a high degree of presicion - I tend to think that trying to push things to the very edge of the theoretically possible is a mistake. And when you run the numbers you tend to find that most people wind up in the 500-1000cal range anyway. But it's nice to know that there is room for individual adaptations, neh?

Hey Melkor, I just 19% body fat. Is that right? It seems a little low. I weigh 168, and my BMI is pretty high, so what is up?

Lots of muscles, probably - I don't like BMI as a general rule for us former obese folks. It took a lot of muscle to carry all that weight around, and if we're lucky, we keep most of it while dieting down.
 
 19% is very good - you need about 4 more to get into Jessica Simpson/Alba/Biel territory of around 15%, but you're already at a very healthy and athletic level.

Original Post by melkor:

Also, keep in mind that the Tanita uses electrical impedance that passes through your lower body while Covert Bailey's test is mostly concerned with upper body measurements - it's entirely possible that you've got an uneven distribution of bodyfat and consequently a lower percentage in your top half.

When I took the Covert Bailey test it asked for mainly lower body measurements. since it asked for my sex (female) and age first, it must take those into account. I hope it's accurate, I like the number it gave me.

Different results from different test are due to the different ways of calculating each one. I hear there are thousands of different algorithms.  What this mean is, if you took ten different tests and fell between, say,  25% and 32% on each one then you have a pretty fair idea of your probable range. More specific test require more specific measurements (e.g., measure exactly at the point between your elbow and shoulder).

To gauge your progress, pick a test you like and keep track of your measurements as accurately as you can. Write down exactly where you measured or even take pictures. It may not be a measure of the absolutely true percent of fat in your body, but repeating the same measure over time will at very lease track progress. [hint: you can do the same with just tracking inches].

Melkor, that is really great information to know.

I used this site to calculate from caliper measurement which gave 16 to 23.7% compared to Trainer's value of 14.1 {but that was calculated for 20 year old and not 70 which doesn't help.]

The site also gave 28.6% by tape measurements which is comparable to Covert Bailey results of 28.3% and my Tanita Scale of 28.5% for same time. That really makes me happy.  On the other hand, the closeness is almost to close for comfort and hope it isn't a onetime fluke.

Keep in mind that the Healthy range for Tanita is from 21 to 36% which is higher than that stated for caliper measurement ranges.

Keep in mind that the Healthy range for Tanita is from 21 to 36% which is higher than that stated for caliper measurement ranges.

Oh, I didn't know that. That's a little more reassuring.

Thanks Melkor -- that "phord" site is brilliant.  (Aaand, I've been eating too much...)

Hey, thank Phord - he's the one who made it! 

Original Post by parkagirl:

Keep in mind that the Healthy range for Tanita is from 21 to 36% which is higher than that stated for caliper measurement ranges.

Oh, I didn't know that. That's a little more reassuring.

While looking for something else, I ran into this reference which states that WHO is the most authoritative for the ranges and that is what Tanita is using compared to other calculators using this one.

Age-Adjusted Body Fat Percentage Recommendations from WHO

Women

Age                 Underfat     Healthy Range Overweight     Obese

20-40 yrs     Under 21%     21-33%             33-39%         Over 39%

41-60 yrs     Under 23%     23-35%             35-40%         Over 40%

61-79 yrs     Under 24%     24-36%             36-42%         Over 42%

[had a hard time getting this organize so you men will have to go to reference to see data, sorry]

vs.

Body Fat Categories Traditional

Women Men Classification

10-12% 2-4% Essential Fat

14-20% 6-13% Athlete

21-24% 14-17% Fitness

25-31% 18-25% Acceptable

>32% >26% Obese