On 6/15/12 3:26 PM
Dear Dr. Chow:
I recently read with interest your attempt to address the obesity issue using mathematical formulas. I am a Family Physician with a long-standing interest in neuroscience, especially the interface between food and brain function. I have also had a long-standing interest in obesity.
As you likely know,
· –People with normal body composition usually don’t have brain dysfunction symptoms.
· –People with excessive body fat usually do have such symptoms regardless of their weight or size.
· –Some people with normal body composition will suddenly develop a few brain dysfunction symptoms and within 2-4 weeks the relative amount of fat in their body will begin to increase.
· –Some people with excessive body fat and brain dysfunction will notice that their symptoms start to improve (usually with targeted treatments) and within 2-4 weeks the relative amount of fat in their body will start to drop.
To me this suggested that when it comes to fat storage, the brain often calls the shots.
We now know that excessive fructose primarily from sucrose and HFCS is the driving force behind insulin resistance and central obesity. When someone with insulin resistance consumes high glycemic carbohydrates, especially from grains, their brain is subjected to magnified glucose spikes. Because high levels of glucose are toxic to neurons, over time these spikes tend to trigger diffuse brain dysfunction characterized by up to 22 brain dysfunction symptoms. We now call this disease process Carbohydrate Associated Reversible Brain syndrome or CARB syndrome. Because the brain plays a key role in auto-regulating fat stores, people with CARB syndrome begin to store extra fat even as they lose weight (mostly lean body mass) dieting.
Although a person with CARB syndrome will store more fat if they increase their caloric intake, calories are not the cause of the fat storage—that would be excessive fructose and high glycemic carbohydrates. Thus any mathematical model of obesity must go well beyond calories to be useful. There is mounting evidence that the type of food eaten plays a key role in determining how much of that food is stored as fat. Does you model take into account any of these factors?
William L. Wilson, M.D.
Dear Dr. Wilson,
Thanks for your message. Our modeling efforts do include the effects of carbs on fat storage. However, there are not enough long term longitudinal studies of how diet composition affects fat deposition to claim definitively that excess carbs enhance fat storage. We are currently undertaking such studies at the NIH. However, there is clear experimental evidence that caloric intake beyond energy expenditure, regardless of composition, will lead to excess body weight and fat.
Carson C. Chow,
Laboratory of Biological Modeling
Dear Dr. Chow:
Thanks for your reply. Although calories certainly do play a role in promoting fat storage I think that diet composition also plays a key role in determining body composition (see below and attached). I have measured the body composition of many women with pre-terminal anorexia and they always have some degree of excessive body fat in relationship to their lean body mass. This certainly can’t be explained by excessive calories. When these women do eat it is almost always food containing sucrose, HFCS and high glycemic carbohydrates.
When auto-regulatory functions are intact, short-term over feeding doesn’t appear to lead to significant fat storage. When these function are disrupted by consuming foods containing excess fructose and high glycemic carbohydrates, fat storage tends to occur even if lean body mass is lost by under-eating. That’s how you end up with an obese thin person. I
I remember taking care of two female patients who both lost 30 pounds. When I measured their body composition, one lost mostly lean body mass and the other lost mostly fat. The first patient was severely restricting calories and the second changed her diet by eliminating sugar, HFCS and high glycemic carbohydrates without over-restricting calories. Any view of obesity must explain these empirical observations. Take care.