Thursday, 31 July 2014

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


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

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 Eout.

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 = Ein (corr for digestion) - Eout (BMR/RMR + TEF + TEA + SPA/NEAT)
__BMR/RMR & TEA ∝ weight
weight → Eout
__If Ein = constant, Eout (Ein - Eout) → weight
weight → weight
∴ Figure 1 is wrong.


carbsane said...

Geez ... and I was hoping you'd explain the meaning of this nonsense from that paper :p

carbsane said...

I posted a pic. Hope it shows up or this comment makes no sense!!

Nigel Kinbrum said...

That's the Taubes "a small error in caloric intake results in an infinite change in weight/fat mass" nonsense.

I'll add it in.