Homeostasis and the Regulation of Fat: A Hypothesis about Why Most Diets Fail

Homeostasis is critical for survival. As organisms, we encounter constantly changing situations. Thus, we need physiological mechanisms to regulate our sensitive internal environments. Homeostatic controls function outside of our conscious awareness to maintain body temperature, salt levels, oxygen and carbon dioxide levels in our blood and so forth. If these control mechanisms didn't exist, life could not persist.

But somehow, we assume that the regulation of our fat tissue is controlled -- not by the mechanisms of homeostasis -- but by the number of calories we eat.

Why do we assume this?

For the past 70+ years, we've convinced ourselves that weight maintenance is a simple matter of accounting. "Calories In" and "Calories Out" matter. When we eat "too many" calories or don't burn off "enough" calories, we become fat. That's the end of the story.

This theory, the Caloric Balance Hypothesis, leaves no room for homeostatic regulation of fat tissue. So if we acknowledge that factors like insulin, glucagon, the sex hormones, and other biochemical factors can manipulate our fat tissue, then we indirectly reject Caloric Balance.

So what does the evidence say? Does homeostasis control how we get fat or not?

1. Here is a quote from Chapter 25 of Harpers Illustrated Biochemistry. The title of the subsection is 'Hormones Regulate Fat Mobilization. Insulin Reduces the Output of Free Fatty Acids.'[1]

"The rate of release of free fatty acids from adipose tissue is affected by many hormones that influence either the rate of esterification or the rate of lipolysis. Insulin inhibits the release of free fatty acids from adipose tissue, which is followed by a fall in circulating plasma free fatty acids. It enhances lipogensis and synthesis of acyl-glycerol and increases the oxidation of glucose to carbon dioxide via the pentose phosphate pathway. All of these effects are dependent on the presence of glucose and can be explained, to a large extent, on the basis of the ability of insulin to enhance the uptake of glucose into adipose cells via the GLUT 4 transporter."

These observations support Lipophilia and appear to refute Caloric Balance.

2) Here's a quote from another article: 'The role of the hormones in weight management':[2]

"The etiology of obesity is multifactorial... The physiological aspects of obesity include body metabolism, hormones, and the neurological components of appetite regulation."

Many in the obesity research community willingly acknowledge that hormones such as insulin, leptin, and glucagon play key roles in fat metabolism. So why does this not cause researchers to pause and reconsider their fundamental hypothesis that calories and calories alone make us fat?

3. For more discussion, read Life Without Bread -- particularly Chapter 5.[3]

4. Or read Gary Taubes' Good Calories Bad Calories (pgs 373-5, in particular) for some nice observations about homeostasis. Consider this choice quote from page 374: "Understanding energy balance and weight control requires Claude Bernard's harmonic ensemble perspective of homeostasis: an appreciation of the entire organism and the entire homeostatic web of hormone regulation."[4]

Why treat fat regulation differently from body temperature regulation, the regulation of oxygen levels in our blood and so forth? It's clearly a physiological phenomenon. And doesn't that fact alone completely refute the notion that 'calories count'?

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1.Robert K. Murray, Daryl K. Granner, Victor W. Rodwell Harper's illustrated biochemistry McGraw Hill (2003).

2.LoCicero, Karon R. The Role of Hormones in Weight Management Douglas Laboratories (March 2007).

3.Taubes, Gary. "Good Calories, Bad Calories." pp 373-375. New York: Knopf (2007).

4.Allan, Christian and Lutz, Wolfgang. "Life Without Bread." New York: McGraw-Hill (2000).

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