Diabetes and the “Obesity Paradox”

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We hear constant warnings about how fatness leads to diabetes. But a wide range of studies show heavy people live longer and do better with diabetes and heart disease. This is called the “obesity paradox.” What does it mean?

In an article in The New York Times, science writer Harriet Brown reports on the work of Dr. Mercedes Carnethon at Northwestern University. Dr. Carnethon has found that thinner people with diabetes have twice the death rate as those who are overweight or obese.

Carnethon’s findings are typical. As Brown writes,

In study after study, overweight and moderately obese patients with certain chronic diseases often live longer and fare better than normal-weight patients with the same ailments.

Protective effects of weight have been found in heart failure, people undergoing dialysis, and those with coronary artery disease, stroke, kidney disease, and high blood pressure. Not only that — researcher Katherine Flegal PhD, has shown that overweight Americans have less risk of dying, on average, than normal-weight people. Mildly obese people have about the same risk of death as normal-weight people and a much lower risk of death than underweight people.

Studies of people over 70 years of age in Australia, Canada, and the US have each found that overweight (but not obese) people had the lowest risk of dying from any cause.

I have to ask. How can they keep calling these findings “paradox?” In how many cases can a theory (like “obesity kills”) fail before its failure is no longer a “paradox?” When do we start to think that maybe the theory is wrong?

There are other explanations of what is happening here. Maybe it’s that being sick puts a strain on the body, and some extra weight helps the body meet those demands. Without it, bodies may possibly become “malnourished” even at “normal” weight. That’s how fatness might be a risk factor for illness but still help you once you get the illness.

Another study by Dr. Carnethon seems to back this up. She found that at diabetes diagnosis, only about 20% of people with Type 2 were normal weight. But people among those 20% much more likely to die during 15 years of follow-up than the 80% who were overweight and obese.

Another theory is that thin people who get heart disease or diabetes may have worse genes. Otherwise they wouldn’t get sick in the first place. Some, like cardiologist Carl Lavie, MD, even say that heart disease in thin people may be a different illness than heart disease in heavier people.

A different illness? It sounds like these guys are desperate to protect their theory from the data. But other scientists seem more open-minded.

Dr. Neil Ruderman, an endocrinologist at Boston University School of Medicine, believes that thin people can still have a lot of insulin resistance and bad cholesterol. They may not have much fat, but what they have is around their middle. This abdominal fat is likely to creep into the liver, pancreas, and heart where it can shorten life.

Ruderman calls these people “metabolically obese normal weight people.” Eek! So you be thin and still be “obese!” What chance do we have?

Here’s a possibility. Weight is acting as a marker for fitness. In other words, overweight people are at risk because they tend to be out of shape. A series of studies at the Cooper Institute in Dallas showed that being fat and fit is better than being thin and out of condition. Exercise may not lead to weight loss, but it does strengthen the heart and reduce fat in the liver, where fat seems to do damage.

The explanation of the “obesity paradox” may be simple — it’s not weight that causes health problems. It’s the stress, lack of fitness, and the insulin resistance that are often seen in heavy people that make them sick.

Fatness itself may be somewhat protective. That may be one reason bodies become fat, as protection. So thinner people who share those risk factors are at the most risk of all and are most likely to die from illnesses like heart disease and diabetes.

Exceptions to this might be obstructive sleep apnea, knee, and hip problems. Those do seem related to fatness in some studies.

In fact, it seems probable that insulin resistance causes fatness more than the other way around. They’re a vicious cycle.

My point is that losing weight by getting fit might be great, especially the “getting fit” part. Losing weight by restricting calories is much less likely to help and may even hurt if you already have diabetes, heart disease, or other major illness.

Hey, it’s my birthday this week (November 9). Give me a present by going to, reading a blog entry or two, and maybe leaving a comment.

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