Nutrition TDEE - why add "exercise" multipliers?

[Sean M]

I've never understood the activity/exercise multipliers on TDEE calculators.

The BMR (basal metabolic rate) portion makes sense - how many calories you burn at current gender/height/weight, if you stayed relaxed in bed all day.

What I don't get is: if you are over-fat, you have tons (weeks or months) of extra energy already in your body. If you want to lose weight, why is energy added to the equation for weight/fat loss beyond BMR?

Why don't we just eat/fast at BMR (which is probably below where you are eating now...otherwise you wouldn't have excess body fat) and whatever activity we do is fueled by all the fat on our waist and hips?

In other words: why are we fueling our current size minus 10-20%, rather than fueling our desired size (lean body mass plus desired/healthy body fat percentage)?

 

[Oscar]

I've never understood the activity/exercise multipliers on TDEE calculators.

The BMR (basal metabolic rate) portion makes sense - how many calories you burn at current gender/height/weight, if you stayed relaxed in bed all day.

What I don't get is: if you are over-fat, you have tons (weeks or months) of extra energy already in your body. If you want to lose weight, why is energy added to the equation for weight/fat loss beyond BMR?

Why don't we just eat/fast at BMR (which is probably below where you are eating now...otherwise you wouldn't have excess body fat) and whatever activity we do is fueled by all the fat on our waist and hips?

In other words: why are we fueling our current size minus 10-20%, rather than fueling our desired size (lean body mass plus desired/healthy body fat percentage)?

As per leangains, we can use only a given amount of energy from fat storage. He estimates 500 calories for a male per day, maybe 700 calories for a very fat male. So if the deficit is more than 500 calories per day, you would be obtaining that energy from your muscles.

In other words, about 500 calories is the maximum deficit for a male in order to minimize muscle loss.

 

[Kenny Croxdale]

The BMR (basal metabolic rate)...

BMR Calculators

These calculators provide you with a vague ball park figure of what your energy expenditure is.

A More Effective Method

As I have posted before. The most practical, effective method is a...

Three Day Recall

1) Write down everything you consume for three days.

2) Divide that by three

That provides your "Daily Average".

Gain/Maintain/Lose

1) Gaining Weight: If you are gaining weight, you are in a surplus of calories

2) Maintaining Weight: If you weight remain constant, you're calorie intake/energy expenditure is balanced.

3) Losing Weight: If you are losing weight, you are in a deficit calorie intake.

The 20% Rule

Research (Dr Lanye Norton and Dr John Ivy, independent of each other) found decreasing calorie intake by approximately 20% maximized fat loss while preserving muscle mass. The reverse is true for gaining; a 20% increase in calorie intake ensured more muscle mass was increased and minimized the about of fat gain.

The MATADOR Cyclical Diet Study

This study determined alternating from maintenance calories to a calorie deficit every two week ensured weight loss. The research found that it takes the body about two weeks to adapt (The General Adaptation Syndrome).

Once adaptation occurs, progress stops. Thus, by alternation calorie intake, you trick the body into losing weight.

This method can also be used for gaining weight; going from maintenance to a surplus every two weeks.

This study simply reinforces what Bodybuilder have done for decades; Bulk and Cut.

However, the Bodybuilders often increased calories too high for the bulk, which dramatically increase body fat.

With cutting they decreased calories too low, dramatically decreasing muscle mass.

...about 500 calories is the maximum deficit for a male in order to minimize muscle loss.

500 Calories

That closely approximates "The 20% Rule".

With that said, "The 20% Rule" is more individualized based on each individual's body weight, more so that the one size fits all 500 Calories.

 

[Sean M]

@Oscar Interesting, I’ll look into that idea.

If we run out of fat (in a day or in total), does the body go right for muscle? Or are there other structures it eats before muscle? (as I understand it, there is a long/energy intensive process involved in converting muscle fiber to usable energy...don’t we have spare amino acids floating around it can more easily convert to glucose for energy?)

 

[Kenny Croxdale]

If we run out of fat (in a day or in total), does the body go right for muscle?

Glucose

Individual on a Traditional High Carbohydrate Diet have up to 500 gram of glucose stored.

Most training program are not going to burn through that amount of glucose and then canabolize muscle.

Fasting

Research show that fasting up to 72 hour/three days primarily burn ketones and preserves muscle

Plenty of Body Fat To Burn

Let's say someone is 170 lbs and 10% body fat.

That means they have 17 lbs of fat available for energy.

Doing The Math

A pound of fat contains roughly 3500 calories X 17 lbs of body fat = 59,500 calories; as you previously mentioned, you have a ton of energy at your disposal.

Preservation of Muscle

The last thing the body does is break down protein for energy. The survival mechanism of the body realized that muscle mass is necessary.

Thus, the body utilize glucose and fats/ketones first. If protein is utilized for energy, very little is used.

 

[Oscar]

@Sean M I´ve been tracking macros and doing an analysis I think you will find interesting.

For the last 2 months I have been traking calories with Cronometer and waist circumference and analyzing how my waist reacts to the calories. So far I have dropped from 90 cm waist to 85 cm. This is the analysis:

	Days elapsed	Waist reduction, cm	Weekly waist reduction	Average daily calories during period
From 90 cm to 85 cm waist	37.00	5.00	0.95	2,243
From 88 cm to 85 cm waist	18.00	3.00	1.17	2,000

I have found eating about 2000 calories in average, I´m losing about 1 cm per week. By this information, I have decided not to go below 2000 calories, as it would probably be counterproductive and make me lose more muscle unnecessarily. This is in line with the procedure proposed by @kennycro@@aol.com (but done for 60 days instead of 3 days ).

The data comes from the below table, downloaded from Cronometer:




In order to have an idea if I´m losing muscle, I´m also tracking hip to waist ratio and other perimeters. So far so good.

I´m tagging @Mark Limbaga who was discussing tracking macros on another thread.

 

[Sean M]

Glucose

Individual on a Traditional High Carbohydrate Diet have up to 500 gram of glucose stored.

Most training program are not going to burn through that amount of glucose and then canabolize muscle.

Right, so like 2,000 calories. Plus weeks in your fat reserves: 20 pounds of extra fat is 36,000+ calories, or 18-ish days at 2,000/day.

I don't get the logic of how, in the presence of 38,000+ calories (the first day's worth is right there on the organs and muscles as glycogen), we need to eat only slightly below TDEE (but above BMR) to lose weight? Shouldn't the glycogen storage (which is constantly replenished by dietary glucose or, in the absence of it, dietary or body fat) be subtracted from intake needs?

So like, I agree that we need to be below BMR to lose weight. I'm just missing the step that says those calories have to come from outside...when we have weeks of energy already in us?

 

[Anna C]

So like, I agree that we need to be below BMR to lose weight. I'm just missing the step that says those calories have to come from outside...when we have weeks of energy already in us?

Not at all a diet expert... But my impression (or guess) is that is has more to do with simplicity and compliance in the weight loss process than what is happening metabolically. Most people are just not going to comply with that big of a caloric deficit, even if the body could handle it in the initial stages. Or if they did, it would become complicated to then adjust back when the glycogen stores were lower or anything else had changed.

 

[Sean M]

Not at all a diet expert... But my impression (or guess) is that is has more to do with simplicity and compliance in the weight loss process than what is happening metabolically. Most people are just not going to comply with that big of a caloric deficit, even if the body could handle it in the initial stages. Or if they did, it would become complicated to then adjust back when the glycogen stores were lower or anything else had changed.

I'm in the "if I could get all my nutrition in one vitamin a day, I would" camp. I have no issues fasting, I haven't gone more than 24 hours before, but I feel exactly the same from 12-24 hours. My wife is the opposite, so I can understand the compliance/feasibility aspect of it.

I'm so left brained that the (to me) obvious way to eat below maintenance calories is...to not eat at all!

 

[Oscar]

Those who are very lean may opt for even less. If you’re wondering why, grab a notepad. Mathematical models suggest that 69 calories worth of fat per kilogram of body fat can be mobilized without muscle loss (ref. 10,12). An 80-kilogram (175-pound) man with 25 percent body fat has 80 x 0.25 = 20 kilograms (44 pounds) of fat mass. Theoretically, he can sustain a caloric deficit of 20 x 69 = 1,380 calories without losing muscle mass.

This is from Leangains Method.

The 100.000 calories we have stored as fat are not in the bloodstream readily available to be used. As I understand it, the 69 calories per kg per day refer to the rate at which our own body fat can be removed from the stores and put to use.

 

[Sean M]

This is from Leangains Method.

The 100.000 calories we have stored as fat are not in the bloodstream readily available to be used. As I understand it, the 69 calories per kg per day refer to the rate at which our own body fat can be removed from the stores and put to use.

Interesting. Citation?

By my calculation, for a 200 pound guy, that works out to 6,200 calories. Seems like enough to last a full day?

 

[Oscar]

Interesting. Citation?

By my calculation, for a 200 pound guy, that works out to 6,200 calories. Seems like enough to last a full day?

Its actually per kilo of stored fat. So a 90 kg guy with 20% body fat has 18 kg of fat, times 69 is 1242 calories per day. You will last a full day, but consume about 800 calories of your precious muscles.

 

[Sean M]

Its actually per kilo of stored fat. So a 90 kg guy with 20% body fat has 18 kg of fat, times 69 is 1242 calories per day. You will last a full day, but consume about 800 calories of your precious muscles.

Begs the question...why not then just eat 800 calories (instead of 3x that like the calculator wants you to)?

 

[Oscar]

Begs the question...why not then just eat 800 calories (instead of 3x that like the calculator wants you to)?

Good point. I dont know. Maybe you can keep muscle mass by having one large dinner or two large meals for a total of 1200 calories or so. Many studies and anecdotal experience have shown the opposite, as far as I know. But are you willing to risk your muscles to try it?

 

[Kenny Croxdale]

69 calories per kg per day refer to the rate at which our own body fat can be removed from the stores and put to use.

Resource

What research source states that?

 

[Sean M]

Good point. I dont know. Maybe you can keep muscle mass by having one large dinner or two large meals for a total of 1200 calories or so. Many studies and anecdotal experience have shown the opposite, as far as I know. But are you willing to risk your muscles to try it?

I'm just not convinced it's only fat or muscle. There are other non-fat, non-muscle sources of amino acids (protein) in the body: excess skin, immune cells (the ones causing inflammation), excess connective tissue, etc. I imagine the body would prioritize that low-hanging fruit before doing the hard work of breaking down muscle belly tissue for energy.

 

[Oscar]

Resource

What research source states that?

Kenny, that's from leangains book. He cites the below studies, which I haven't read.

10. “The Ketogenic Diet’s Impact on Body Fat, Muscle Mass, Strength, and Endurance.” The Science of Fitness - SCI-FIT, The Ketogenic Diet’s Impact on Body Fat, Muscle Mass, Strength, and Endurance • Sci-Fit

12. Alpert, S. S. (2005). “A limit on the energy transfer rate from the human fat store in hypophagia.” Journal of Theoretical Biology, 233(1), 1–13.

 

[Hung]

cortisol article on T-nation could be helpful to understand how the body work:

The Best Damn Cortisol Article Ever

What It Really Does and How to Control It It's been called the stress hormone, the belly fat hormone, and the thief of gains. But it doesn't have to be any of those. Here's how to control it. Cortisol is like the boogeyman. To scare lifters away from doing extreme things, we tell them that...

www.t-nation.com

 

[Sean M]

cortisol article on T-nation could be helpful to understand how the body work:

The Best Damn Cortisol Article Ever

What It Really Does and How to Control It It's been called the stress hormone, the belly fat hormone, and the thief of gains. But it doesn't have to be any of those. Here's how to control it. Cortisol is like the boogeyman. To scare lifters away from doing extreme things, we tell them that...

www.t-nation.com

This article further reinforces my view that the human metabolism is not a machine (calories in < calories out), but a complex system of chemical "batteries".

E.g. two identical people (same BMR/TDEE) can eat the same calories in a day, one eats all his over 4 hours at the end of a 20-hour fast, the other spreads it out over 12 hours...and their partitioning and use will be very different due to the hormonal setup. Both can eat at -20% TDEE but one may experience more fat loss and less non-fat mass loss than the other for the same reason.

 

[Anna C]

This article further reinforces my view that the human metabolism is not a machine (calories in < calories out), but a complex system of chemical "batteries".

Yes, I agree... I'm learning about some other factors that affect fat burning vs. storage from the book "The Fat Switch", such as fructose (both that we consume, and that our bodies make internally), uric acid, and other things.