Paul Campos, a professor of law at the University of Colorado in Boulder, has published a rant on weight and health on The New Republic Online. It is titled, “What the Diet Industry Won’t Tell You.”
Campos carefully chooses which literature he reviews to make the point that it is not obesity that is bad for you, but rather a sedentary lifestyle. He says:
“Fat people might be less healthy if they’re fat because of a sedentary lifestyle. But, if they’re fat and active, they have nothing to worry about.”
Professor Campos makes the same mistake interpreting the medical literature about obesity as do many others. He fails to understand that not everybody who is obese is at risk for serious health consequences like Type 2 diabetes and heart disease (Full text article: Diab Vasc Dis Res 2005 Oct;2(3):105-12).
Some people who are obese may well be “fat and happy”. But the rest have inherited a predisposition to become resistant to the hormone insulin when they gain body fat, particularly when the fat accumulates around the gastrointestinal organs. This type of fat is known as “visceral fat”.
Insulin resistance and compensatory insulin resistance
It is the resistance to insulin and the associated increase in insulin levels that occur when the body tries to overcome the resistance (called compensatory hyperinsulinemia) that causes the serious medical problems associated with overweight and obesity. Insulin resistance and compensatory hyperinsulinemia, sometimes called the insulin resistance syndrome or IRS for short, is associated with a whole host of pathologies, including:
- Elevations of blood glucose which can progress to Type 2 diabetes
- High blood pressure
- Abnormal lipids (high triglycerides and low HDL (“good cholesterol”)
- Vascular disease (coronary artery disease, carotid artery disease, peripheral vascular disease)
- Clotting problems
- Problems with inflammation
- Nonalcoholic fatty liver disease
- Sleep apnea
- Polycystic ovary disease
- Certain forms of cancer
Approximately 75% of individuals in the most insulin-resistant tertile are overweight/obese. That means 25% of insulin-resistant individuals are not overweight/obese. Thirty percent (30%) of those in the most insulin-sensitive tertile are overweight/obese but are at low risk for IRS. Metabolic benefit and decrease in risk of CVD following weight loss occur primarily in those overweight/obese individuals that are also insulin resistant. (Full text article: Diab Vasc Dis Res 2005 Oct;2(3):105-12)
BMI is not a good measure of risk for serious health problems related to overweight/obesity
It is true that BMI is not the best measure for risk for serious health problems related to accumulation of body fat. BMI is far too gross of a measure, merely determining the relationship of weight to height. The reason why it is popular in medical settings is because it is easy and cheap to measure.
Better measures of risk of fat-related health problems are measures of waist circumference, particularly when compared to hip circumference (i.e., waist to hip ratio). This measure starts to get closer to determining if a person is an apple (central obesity) or a pear (lower body obesity) body type. Since risk is tied to central obesity, particularly visceral fat, an elevated waist to hip ratio may be more helpful than BMI in determining risk related to weight.
The gold standard in determining risk is a measure of visceral fat itself. This can be done with imaging techniques, such as MRI or CT scans. These tests, of course, are much more difficult to obtain and are expensive. It is interesting that at least one Japanese company, Hitachi, a manufacturer of MRI equipment, has developed a weight loss and fitness program for their employees that is based on measuring the volume of visceral fat via CT scan and then encouraging people to reduce it!
Campos does have it right when he talks about the importance of physical activity. It has been found to improve insulin sensitivity independent of any impact on weight loss. However, for many individuals prone to insulin resistance, exercise in the absence of weight loss is not enough to restore insulin sensitivity to ranges associated with a reversal of associated pathologies.
So when Professor Campos concludes his article by saying,
“So what should we do about fat in the United States? The short answer is: nothing. The longer answer is that we should refocus our attention from people’s waistlines to their levels of physical activity.”
He really only has it partly right, but he is mostly wrong. We do need to exercise more, however, for the millions of people around the world who will develop insulin resistance and compensatory hyperinsulinemia when they gain weight around their mid-section, such narrowly focused advice could have deadly consequences.