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Originally Posted by Muata
Now, I'm definitely part of the energy balance equation school of thought, but I found his interpretation of the this equation very interesting and wanted to know what you guys thought:
from page 293
Change in energy stores = Energy intake - Energy expenditure The first law of thermodynamics dictates that weight gain--the increase in energy stored as fat and lean-tissue mass--will be accompanied by or associated with positive energy balance, but it does not say that it is caused by a positive energy balance--by "a plethora of calories," as Russell Cecil and Robert Loeb's 1951 Textbook of Medicine put it. There is no arrow of causality in the equation. It is equally possible, without violating this fundamental truth, for a change in the energy stores, the left side of the above equation, to be the driving force in cause and effect; some regulatory phenomenon could drive us to gain weight, which would in turn cause a positive energy balance--and thus overeating and/or sedentary behavior. Either waY, the calories in will equal the calories out, as they must, but what is cause in one case is effect in the other. All those who have insisted (and still do) that overeating and/or sedentary behavior must be the cause of obesity have done so on the basis of this same fundamental error: they will observe correctly that positive caloric balance must be associated with weight gain, but then they will assume without justification that positive caloric balance is the cause of weight gain. This simple misconception has led to a century of misguided obesity research. When the law of energy conservation is interpreted correctly, either of two possibilities is allowed. It may be true that overeating and/or physical inactivity (positive caloric balance) can cause overweight and obesity, but the evidence and the observations, as we've discussed, argue otherwise. The alternative hypothesis reserves the causality: we are driven to get fat by "primary metabolic or enzymatic defects," as Hilde Bruch phrased it, and this fattening process induces the compensatory responses of overeating and/or physical inactivity. We eat more, move less, and have less energy to expend because we are metabolically or hormonally driven to get fat.
Muata |
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Originally Posted by ReginaW
When I read that part of the book....my first reaction was "aha!" someone finally has stated it in terms that make sense from the perspective of the laws of thermodynamics....he's right, the laws go both ways, and it makes sense why weight gain happens when you take the laws from the opposite side of the equation!
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OR to say it another way. . .
The equation
Energy intake - Energy expenditure = Change in energy stores
does
NOT say
JUST that
IF Energy intake - Energy expenditure THEN there is an EQUAL Change in energy stores
Which would imply a causal relationship.
RATHER, it says
ONLY that Change in energy stores
MUST be EQUAL to Energy intake - Energy expenditure.
After looking at what I had written I think I should try a second time.
Changing the equation to read
Energy intake - Energy expenditure = Change in energy stores
so it looks like the following. You can now say that the equation does NOT JUST say that IF Energy intake - Energy expenditure is non zero THEN the Change in energy stores is the same amount, positive or negative. Which would imply a causal relationship.
An “IF, THEN” logic operation.
To use an different example, sort of a converse one to demonstrate the “IF, THEN” logic operation versus the equal operation, you cannot say
Cows = Grass Eaters.
That would mean that a Grass Eater would be a Cow - not so! Lots of other animals eat grass. The statement:
IF a Cow
THEN a Grass Eater, is correct, as it turns out. BUT the inverse:
IF a Grass Eater
THEN a Cow, is not.
People forget, or do not know, that using equal between to operands (formulii) allows BOTH “IF,THEN” versions, i.e. f{a,b,c,d} = f{w,x,y,z} allows saying IF f{w,x,y,z], THEN f{a,b,c,d] BUT the inverse IF f{a,b,c,d}, THEN f{w,x,y,z} is also allowed and true. However, the truth of an “IF, THEN” statement does NOT imply the truth of the inverse.
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