Posted by: Joseph Dixon | May 27, 2014

Unintended Consequences; Ancel Keys, Cholesterol, and the Transition to an Obese Society; Part XIV, The Start of Obesity, Part 4, The Convergence of Three Powerful Forces

The three previous chapters covered three powerful changes in American society in the late 1900s that converged to overwhelm the energy regulation system in humans such that a large percentage of Americans became overweight or obese over a relatively short 30-40 year period.

To recap, these powerful forces were:

1.The development of a myriad group of food products that were both super palatable and energy dense, plus the proliferation of fast food restaurants, such that one was located at every highway exit and within walking distance of most Americans.

2.The infusion into the home of two powerful digital media systems that were able to hijack the spare time of most Americans leading to a sedentary life style.

3.The continued income inequality in the US coupled with a more dangerous neighborhood environment due to drugs, guns, and gangs compelled mothers and caregivers to keep their children inside watching television and appeasing them by feeding them absolutely addictive, nutrient poor, energy rich snack foods.

However, there are always forces within society that will take advantage of the complexity of an action and will propose an explanation that is simple, straight-forward, yet totally incorrect. I call these people, “the nutrition crazies” and they have written thousands of books shouting their view that one thing alone is responsible for the giant obesity earth quake that has changed the American landscape in such a drastic way.

One group of “the nutrition crazies” has blamed Ancel Keys and his discovery that high blood cholesterol was an important risk factor for CHD as a reason for the obesity crisis. Another group of “nutrition crazies” has blamed a shift to a greater percentage of total kcal coming from carbohydrate as the sole reason for our current obesity crisis. As in most philosophies put forth by quacks, there is some small element of correctness in their assertions that increased carbohydrate intake is an important factor in the obesity epidemic. But as we observed in chapter XI, there were increases in total kcal, carbohydrate, and fat intakes in the American population over this period of time, and all of these have contributed to the increase in obesity.

For the time being, lets discuss the carbohydrate versus fat argument.

When pure carbohydrate and pure fat are burned in a bomb calorimeter, the data observed is that carbohydrates contains 4 kcal/gram and fat contains 9 kcal/gram. The energy in these macronutrients is due to the bonds that are used in each molecule. This energy is derived from where each atom is bonded to its neighbor, and some bonds contain more energy than other bonds. It so happens that the sum of the bonds in 1 gram of fat contains more energy than the sum of bonds in 1 gram of carbohydrate. The basic energy in each of these macronutrients is determined by their chemistry and physics – not by magic. And in fact, these macronutrients have been used to store energy in cells since early evolution because each can do so in a relatively safe and efficient way.

The first law of thermodynamics in physics states that energy cannot be created or destroyed in a close system. Therefore, if these macronutrients are consumed by an animal, the inherent energy in them will not change. No matter what, the animal metabolizes these nutrients by biochemical reactions and the energy released when they are completely converted to their most simple products, carbon dioxide and water, must match the energy that was present in their original configuration. Therefore, the energy difference that was measured in the bomb calorimeter must be maintained in the animal system. This is basic physics and, in fact, this relationship was observed and confirmed many times in studies carried out in the late 1800s and early 1900’s. A review of this topic can be found in the excellent book, “The Fires of Life” by Max Kleiber, a scientist formerly at the University of California-Davis, considered the father of the field, Bioenergetics, which Is the study of energy conservation in living systems.

With the above said, there are situations where a metabolic situation can be established that favors energy storage rather then energy expenditure. However, in this situation, the equations explaining energy distribution must be upheld. The second law of thermodynamics holds in all living systems.

I will discuss this topic in greater detail in a later chapter. But right now I wish to return to the topic of cholesterol, because in the late 1900s discoveries were made that would have a great influence on our knowledge of lipid and cholesterol metabolism and that would lead to advances in medicine.

 


Leave a short comment

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

Categories

%d bloggers like this: