Monday, September 15, 2014

The Obesity Paradox

Fat's bad and thinner is better, right? Maybe not. For instance, overweight men with certain diseases of the heart live longer than men of normal weight with the same diseases. For many of us, the idea that fat can be good and thin may be bad is counter-intuitive. Hence the term: obesity paradox.

I have never looked terribly overweight. I'm six feet and at my heaviest I weighed about 215 pounds straight from the shower. These numbers gave me a BMI of 29.2. A BMI from 25 to 30 is said to be overweight, while anything above 30 is, let's be blunt, fat. A BMI greater than 35 is obese. Hit 40 or more and one is morbidly obese. Link: Calculate Your Body Mass Index (BMI)

Recently, at the urging of my doctors, I've been trying to lose weight. I had my weight down to about 185 pounds before a bowel obstruction forced me to undergo emergency surgery. After being discharged from the hospital, I discovered I had lost ten full pounds. Luckily, I didn't lose any bowel, the surgeon simply removed a tight band of connective tissue. Today, I'm in amazingly good heath. My BMI is 23.7.

I feel good. I'm happy with my new weight and my tummy is almost flat. My friends are not so keen on my new look. "You're too thin," they tell me. "You've got to put some fat on those bones. It's important to have some fat in reserve if and when another health issue surfaces," they say. I used to shake my head "no" when I heard this advice. I have since discovered there is some support for their ideas. In certain cases being somewhat overweight decreases mortality.

In my personal experience, the strongest advocates for keeping some fat on the bones are themselves high on the BMI scale. No paradox here. These people like their weight and want to keep their rotund figures.

But fat people are not the promoters of the obesity paradox. Medical researchers, some of whom were truly puzzled by their findings, are behind this story. T. Jared Bunch, MD, wrote:

I observed the obesity paradox in a published study I conducted while studying at the Mayo Clinic. We looked at 226 people who experienced a heart arrest in the community and were resuscitated. What we found was that people that were slightly overweight (BMI from 25-30) had the highest 5-year survival at 78 percent. People who were underweight had a significantly lower survival at 67 percent, similar to people considered morbidly obese.

In other words, extremes are not good. Being too thin may be bad for you and being way too fat is definitely bad. According to this theory, at six feet I don't want my weight to drop below 140 pounds or climb above 257 pounds. Calculate your BMI and if your number is 40 or more, the obesity paradox is of no concern to you. You are morbidly obese. Lose some weight.

If you are curious as to what weight puts a man of six feet in the BMI sweet-spot, the answer is a weight in pounds from 184 to 221. So, should I put some of the fat back on my bones as recommended by my friends? I think not.

I believe what we are seeing is a failure of the BMI numbers to accurately define healthy weights. Some experts go so far as to claim that the obesity paradox doesn't exist. It is an illusion, a misunderstanding resulting from an overly simplistic way of calculating healthy body weight.

Doctors Vojtech Hainer and Irena Aldhoon-Hainerov wrote in their essay Obesity Paradox Does Exist:

The obesity paradox may be partly explained by the lack of the discriminatory power of BMI to differentiate between lean body mass and fat mass. Higher mortality in the low BMI categories may be due to . . . low muscle mass . . . Many obese patients demonstrate not only increased fat mass but also increased muscle mass. Elderly patients with heart failure who exhibited high BMIs and had improved survival rates also had a better nutrition than many of those patients with lower BMIs.
BMI and triceps skinfold thickness did not predict mortality, while a larger mid-arm muscle area, as a protective factor, did. A composite measure of mid-arm muscle mass and waist circumference was proposed as the most effective predictor of mortality in older men. Men aged 60 to 79 years with low waist circumference and above-median muscle mass demonstrated the lowest mortality rate.

Google "obesity paradox" and you'll find yourself in the middle of controversy. Here's a link to get you started: There's No 'Obesity Paradox' for Stroke, Study Finds. 

If you are still into books. I still am. Visit your local library and borrow The Obesity Paradox by Dr. Carl Lavie. Lavie writes that fat is like real estate: it's location, location, location. Not all fat cells are the same. Abdominal fat is bad, while bottom, hips, upper arms, and thighs is not so bad. For really bad fat, think visceral fat -- the fat surrounding abdominal organs. That stuff can increase fatty acids, the production of inflammatory compounds and create hormones resulting in higher rates of bad cholesterol, blood fat (triglyerides), blood sugar (glucose) and higher blood pressure.

Thin folk with belly fat are often at a higher risk of cardiovascular disease that those considered fat based on their BMI number alone. The truth is, that unlike abdominal fat, saddlebags and thunder thighs may actually be good for you. If you are thinking of liposuction to shrink those difficult to lighten body areas, don't!

Dr. Lavie would like to move the focus from fat to health -- to fitness. As he reports, and I think we all can agree, a person can be exceedingly healthy at many different BMI values. Before putting too much emphasis on a little fat by the BMI standard, improving fitness may deliver far more health benefits for the effort.

Clearly, it's not just total weight that matters; it's where one carries that weight. It's better to be a pear than an apple. Carrying excess weight around the abdomen is bad. Carrying the excess around the hips while keeping the waist narrow is far better. And always try to be fit with good muscle mass. An extremely thin person, with poor muscle mass and no reason to claim they are fit, has more health issues than a mildly overweight person whose fat hides a fit, muscular body.

It may be that as long as you are a small, fit pear, you may well call out triumphantly, "BMI be damned."

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