A calorie is a calorie ... low carbing

[Guest guest]

I thought some of you might like this. You can read the whole article online,

too!

It's a good discussion, IMO, of some of the issues of low carb diets and

macronutrient content of a diet (too bad it doesn't include feast/fast in

there too ...)

http://www.nutritionj.com/content/3/1/9

The principle of " a calorie is a calorie, " that weight change in hypocaloric

diets is independent of macronutrient composition, is widely held in the popular

and technical literature, and is frequently justified by appeal to the laws of

thermodynamics. We review here some aspects of thermodynamics that bear on

weight loss and the effect of macronutrient composition. The focus is the

so-called metabolic advantage in low-carbohydrate diets – greater weight loss

compared to isocaloric diets of different composition. Two laws of

thermodynamics are relevant to the systems considered in nutrition and, whereas

the first law is a conservation (of energy) law, the second is a dissipation

law: something (negative entropy) is lost and therefore balance is not to be

expected in diet interventions. Here, we propose that a misunderstanding of the

second law accounts for the controversy about the role of macronutrient effect

on weight loss and we review some aspects of elementary thermodynamics. We use

data in the literature to show that thermogenesis is sufficient to predict

metabolic advantage. Whereas homeostasis ensures balance under many conditions,

as a general principle, " a calorie is a calorie " violates the second law of

thermodynamics.

....

An example is the recent demonstration of metabolic advantage in a small, pilot

study [<http://www.nutritionj.com/content/3/1/#B7>7] which, despite its

preliminary status, was extremely well controlled. Three groups were studied: A

low carbohydrate group (LoCHO = 1800 kcal for men; 1500 kcal for women), a low

fat group (LoFat, 1800 and 1500); a third group also consumed a low carbohydrate

diet but an additional 300 kcalories were provided (LoCHO+300, 2100 and 1800).

The order of average amount of weight lost was LoCHO = 23 lbs, LoCHO+300 = 20

lbs LoFat = 17 lbs. This work received a good deal of attention in the popular

press. Media reports, however, included comments of experts that " It doesn't

make sense, does it? " " It violates the laws of thermodynamics. No one has ever

found any miraculous metabolic effects. "

([<http://www.nutritionj.com/content/3/1/#B5>5]).

.....

In our previous review of metabolic advantage

[<http://www.nutritionj.com/content/3/1/#B4>4] we showed that there is, in fact,

no theoretical violation of the laws of thermodynamics, and we provided a

plausible mechanism. In general the pathways for gluconeogenesis that are

required in order to supply obligate glucose (e.g. to brain and CNS), in

combination with increased protein turnover, could account for the missing

energy.

.................................................................

Heidi Jean

[Guest guest]

In a message dated 9/21/04 3:51:46 AM Eastern Daylight Time,

heidis@... writes:

The principle of " a calorie is a calorie, " that weight change in hypocaloric

diets is independent of macronutrient composition, is widely held in the

popular and technical literature, and is frequently justified by appeal to the

laws

of thermodynamics.

_____

~~~~> Wow, like evolution violates thermodynamics? I didn't even realize

that low-carbing leading to better weight loss was considered to violate the

Second Law. That seems unimaginably stupid right off the bat. How do all these

people get away with considering themselves credible scientists?

Chris

[Guest guest]

Chris-

>I didn't even realize

>that low-carbing leading to better weight loss was considered to violate the

>Second Law. That seems unimaginably stupid right off the bat. How do all

>these

>people get away with considering themselves credible scientists?

Same way lipid hypothesis scientists do, I guess.

-

[Guest guest]

>~~~~> Wow, like evolution violates thermodynamics? I didn't even realize

>that low-carbing leading to better weight loss was considered to violate the

>Second Law. That seems unimaginably stupid right off the bat. How do all

these

>people get away with considering themselves credible scientists?

>

>Chris

Yeah, I kinda think that the folks who say " a calorie is a calorie "

are ignoring a LOT of good solid studies ... which is surprising,

because both " camps " are pretty much basic science type folks.

Ignoring the issue of how some foods make you want to

eat more, proteins have been shown to make your metabolism

run faster, and some foods are basically not digested well,

and it takes a lot of calories to digest some foods. But the

2nd law issue I hadn't considered either. There is a surprising

amount of knee-jerk anti-low-carb bias out there.

Heidi Jean