Nonequilibrium thermodynamics and energy efficiency in weight loss diets, by Richard D Feinman and Eugene J Fine.

From http://www.caloriegate.com/the-black-box/9-pictures-that-prove-beyond-a-reasonable-doubt-that-calories-dont-count

From Nonequilibrium thermodynamics and energy efficiency in weight loss diets:-

"Conclusion
Emphasis on kinetics and nonequilibrium thermodynamics provides a conceptual framework for understanding the effect of macronutrient composition on maintenance and change of body mass and possibly for analysis of adipocyte metabolism in general. The simple model presented is intended to be consistent with a general shift away from equilibrium thermodynamics and towards a more dynamic analysis of cellular processes."

Sounds plausible. There's only one thing wrong with Feinman et al's article - it's completely wrong!

Consider two rooms:-

Room "A" has an adjustable heater. The heater is adjusted until the room temperature is 20°C.

Room "B" has a radiator, controlled by a wall-stat set to 20°C. The radiator is on, and the room is at 20°C.

We have two rooms of the same size, at the same temperature.

If you plug in & turn on a 2kW fan heater in each room, what happens to the temperature in each room?

Room "A" gets warmer, because there is 2kW more heat power entering it.

Room "B" stays at 20°C, because the wall-stat reduces the heat power from the radiator by 2kW.

The human body stays at 37°C ±~2°C, because there's a Negative Feed-Back loop adjusting the heat power produced, via UCP's, futile cycles, thyroid hormones, shivering and heat conservation/wasting behaviours.

∴ Variable heat power generation due to variable Dietary Efficiency doesn't change E_out.

EDIT: By request, here's Figure 1 from the above study.

This suggests that fat mass & therefore weight can increase indefinitely - at maintenance energy intake, due to the effect of insulin on HSL. This, of course, is quite impossible!

From The Energy Balance Equation:-

Change in Body Stores = E_in (corr for digestion) - E_out (BMR/RMR + TEF + TEA + SPA/NEAT)
__BMR/RMR & TEA ∝ weight
∴ ↑ weight → ↑ E_out
__If E_in = constant, ↑ E_out → ↓ (E_in - E_out) → ↓ weight
∴ ↑ weight → ↓ weight
∴ Figure 1 is wrong.

Why Calories count (where weight change is concerned).

I have to add the words "where weight change is concerned", as calories have little to do with body composition or general health (unless somebody becomes morbidly obese).

From https://docs.google.com/file/d/0Bz4TDaehOqMKSXZHUUVxWnl5VTQ/edit?usp=sharing

Arguments used by Calorie Denialists include:-

1) Calories don't count because the human body isn't a Bomb Calorimeter and treats different macronutrients differently.
 
100g of liquid paraffin burns in a Bomb Calorimeter, yielding 900kcals. In a human, it passes through completely undigested. Ah-ha!, I hear you saying. This proves that the Energy Balance Equation is invalid. Uh, nope!

Calories in = Calories entering mouth - Calories exiting anus

As 100% of liquid paraffin calories entering the mouth exit the anus, Calories in = 0

This is why Sam Feltham's "Smash the Fat" "experiment" is nonsense. A high percentage of the large amount of raw almonds he ate would have exited his anus incompletely chewed, undigested & unabsorbed.

See the picture above? In the late 1800's, W.O. Atwater established Atwater Factors (3.75kcals/g for digestible Carbohydrates, 4kcals/g for Proteins, 5kcals/g for Ketones, 7kcals/g for Alcohols & 9kcals/g for Fats*) using Human Calorimeters, not Bomb Calorimeters. Atwater Factors are pretty accurate.

*Fats containing different fatty acids have slightly different kcals/g. Fats containing long-chain fatty acids are 9kcals/g. Fats containing medium-chain fatty acids e.g. coconut oil are ~8kcals/g.

For more information, see Calories ...


2) Calories don't count because Dietary Efficiency varies for different macronutrients.

Uh, nope! The Heat Power generated by the body is regulated by a NFB loop involving the Hypothalamus, Pituitary, Thyroid Axis, also Uncoupling Proteins (UCP's), also shivering, so as to maintain a body temperature of 37°C ±3°C. If this wasn't the case, different amounts & types of foods (also, changes in ambient temperature & clothing) would cause large variations in body temperature resulting in death, as the enzymes in our bodies function correctly over a limited range of temperatures.

Heat Power generated by the body (W) = Temperature difference between the body & ambient (°C) divided by Thermal resistance between the body & ambient (°C/W)

∴ Dietary Efficiency is irrelevant.

Metabolic rate, diet efficiency and thermodynamics.

From Life and Death: Metabolic Rate, Membrane Composition, and Life Span of Animals

This post is based on https://www.facebook.com/richard.feinman.7/posts/667508920000715:- 
"When people say the laws of thermodynamics, they usually mean the first law, the law of conservation of energy. However, “conservation of energy” can be a sound bite, at the level of “Einstein said that everything is relative.” You have to know exactly what is being conserved. Precise definitions become very important. One of the many difficulties in understanding thermodynamics is that there are simple principles which seem obvious enough but their import is under-appreciated without a real example.

The first law says precisely that there is a parameter called the internal energy and the change (Δ) in the internal energy of a system is equal to the heat, q, added to the system minus the work, w, that the system does on the environment. (The internal energy is usually written as U so as not to confuse it with the electrical potential).

ΔU = q - w (1)

This is how thermodynamics is taught. To go to the next step you need to understand the idea of a state variable. A state variable is a variable where any change is path-independent. For example, the familiar temperature T and pressure P are state variables. It doesn’t matter whether you change the pressure quickly or slowly. The effect on the system is controlled by the difference between the pressure after the change minus the temperature before the change, that is, ΔP. The usual analogy is the as-the-crow-flies geographical distance, say, between New York and San Francisco. This is a state variable: it doesn't matter whether you fly direct or go through Memphis and Salt Lake City like the flights that I wind up on.

Now, U in equation (1) is a state variable. Any process that you carry out will have a change in U that depends only on the initial and final states. However, q and w are NOT state variables. How you design your machine will determine how much work you can get out of it and how much of the energy change will be wasted. Looking at the biological case, two metabolic changes with the same U have no theoretical reason why they should have the same relative amounts of heat and work, that is, the same efficiency (storing fat as compared to generating heat). Of course, they might but there is no theoretical barrier to difference.

In this, the first law contains the suggestion of the second law. The second law is what thermodynamics is really about.... It is the second law that embodies the special character of thermodynamics. Described by Ilya Prigogine, the Nobel-prize winning chemist and philosopher of thermodynamics, as the first revolutionary science, it is the second law that explains how one diet can be more or less efficient that the other."
Ref: Non-equilibrium thermodynamics and energy efficiency in weight loss diets.

To which I replied:-
"Uncoupling proteins (UCP's) vary ATP → ADP + heat energy, so as to maintain the human body at 37°C ±3°C, over a wide range of ambient temperatures.

Therefore, "diet efficiency" is varying over a wide range, for all diets."

Followed by:-
"Here's an example:-

To maintain a body temperature of 37°C in an ambient temperature of 20°C, the body needs to generate ~1kcal/min (~69.8W).

If Diet "A" generates 30W due to metabolic processes, UCP's generate an extra 39.8W.

If Diet "B" generates 40W due to lower "diet efficiency", UCP's generate an extra 29.8W.

According to Life and Death: Metabolic Rate, Membrane Composition, and Life Span of Animals:-
"Not all body tissues contribute equally to BMR. For example, ∼70% of the BMR of humans is contributed by internal organs that constitute only ∼7% of body mass..."

As humans must (& can) survive over a wide range of ambient temperatures while being covered with a wide range of clothing while eating a wide range of diets, UCP activity must be capable of being varied from 0 (ambient temperature ≥37°C) to a very high value (swimming in water at 0°C).

Therefore, "diet efficiency" is irrelevant, as UCP's equalise overall efficiency, to equalise the rate of heat energy generation for a given ambient temperature & clothing.

Taking levothyroxine & overheating in hot weather - the penny drops.

Last night, I was sitting in a hot stuffy pub listening to some excellent music being played at a jam session. During the breaks (when it was quiet enough to hold a conversation), I was chatting with Jack the Rapper. As I was chatting, a thought popped into my head about why I was dripping with sweat, when everyone else in the audience wasn't. Here it is.

The Hypothalamus secretes TRH (Thyrotropin Releasing Hormone) which reaches the Pituitary via the hypophyseal duct.

The Hypothalamic Pituitary Thyroid Axis (HPTA) regulates body temperature. It varies thyroid hormone levels (T4 & T3) which varies Uncoupling Protein (UCP) expression, which varies heat production, which varies body temperature. See Minimal changes in environmental temperature result in a significant increase in energy expenditure and changes in the hormonal homeostasis in healthy adults.

"Thyroid hormones axis Compared with exposure to 24 °C, exposure to 19 °C resulted in small, non-significant increases in total triiodothyronine (T₃) and TSH AUCs and a significant increase in serum free thyroxine (T₄; P=0.03). When the analysis was performed according to the gender, a small but significant increase in serum T₃ AUC was observed in males (P < 0.05) but not in females. Similarly, while the change in free T₄ was highly significant in males (P < 0.002), no significant change was observed in females." Is this why women feel the cold more than men?

My Pituitary doesn't secrete Thyrotropin a.k.a. Thyroid Stimulating Hormone (TSH), so I'm prescribed levothyroxine 125μg/day every day. When the ambient temperature rises, my HPTA doesn't lower my thyroid hormone level as I am running "open-loop". My UCP produces too much heat which makes me overheat. Ker-ching!

From now on, I will adjust my levothyroxine dose to a value where I feel comfortably warm at all times. According to http://www.drugs.com/pro/levothyroxine.html, the half-life of levothyroxine is 6-7 days. Any change in levothyroxine dose will take about a week to get half-way to its final effect on internal heat generation. This could take quite some time!

Continued on Taking levothyroxine & overheating in hot weather - the penny bounces back up.