After smoking, what do you suppose is the No. 2 cause of preventable death among Americans? Car accidents? Drug and alcohol problems? No.

In America, the weight is killing us, literally.

I'm Dr. Caroline Cederquist, giving you The Skinny on Your Health.

A massive study published recently in the Journal of the American Medical Association showed that in the last 20 years, actual deaths due to overweight and inactivity have exploded, now accounting for some 400,000 annually.

Yet because obesity is ballooning in all age groups, and because it takes a while for the effects of overweight to reach the terminal stage, researchers say the actual death rate may be closer to half a million, once the most recent data are included.

But aggressive prevention efforts will make a real difference, scientists say. Because - unlike cancer and drunken drivers - this is one killer we have a lot of control over.

Living Longer, But Not Better

New data show that better preventive and diagnostic care has dropped death rates from cancers, infant mortality, and childhood diseases.

I'm Dr. Caroline Cederquist, with Get The Skinny on Your Health.

Treatments for high cholesterol and wonderful new emergency techniques have also reduced deaths caused by heart attacks.

But dramatic increases in obesity and sedentary living are threatening to counteract these gains.

High blood pressure is on the rise; diabetes is sharply up. With a rapidly aging population, and skyrocketing health-care costs, the consequences of unhealthy lifestyles are more painful to endure and more expensive to address.

Yet experts say that the behaviors that lead to needless disease are about to outpace the developing technologies for treating it.

Good nutrition and healthy living work more wonders than any wonder drug, because it's still true: an ounce of prevention is worth a pound of cure.

Weight Cycling - Yo Yo Dieting

Thanks to some skewed statistics, people once believed that yoyo dieting caused increased health risks. We know better now, but that old concern seems to linger on in popular memory.

I'm Dr. Caroline Cederquist, giving you the Skinny on Your Health.

It turned out the problem isn't with the dieting, but rather, with the statistics. That original study on weight loss and mortality included people losing weight from various causes, including disease or treatments for it, like chemotherapy.

Weight loss in cancer victims is a lot different from that in average dieters, and you can see how lumping it all together could skew the data on death rates.

The truth has always been that there are often significant health gains brought by even minor weight losses. That means that even if you put the weight back on eventually, at least your system had some temporary relief from the burdens of overweight.

So don't worry about yo-yoing, and don't ever give up trying to get healthier.

It's better to have lost and gained than never lost at all.

Erectile Dysfunction and Obesity

Research shows that overweight men are as interested in sex as the next guy; they just may not be as able. Now a recent study has yielded some promising news about that problem.

I'm Dr. Caroline Cederquist, giving you the Skinny on Your Health.

A two-year study examined obese men with erectile dysfunction who were otherwise healthy. Half were supervised in individualized weight-loss treatment and educated about diet, fitness and sexual function.

The other half - the control group - were just given general information about exercise and healthy dietary choices.

All the men in the supervised group experienced some health or sexual function improvements after a weight loss of just 10 percent, and erectile dysfunction was completely alleviated for one out of three. But there was no change in weight or sexual function for the control group, indicating that professional support seems to make all the difference.

We already know that overweight men who initiate weight loss in mid-life have 70 percent less risk of erectile dysfunction than those who remain sedentary.

It all just shows there's a lot of hope for men who seek the right help.

Disability from Obesity

America's obesity epidemic has reached crippling proportions, quite literally, as more and more people are going on disability because of problems related to their weight.

I'm Dr. Caroline Cederquist, giving you the Skinny on Your Health.

Researchers at Rand Health, a non-profit health research organization, examined 16 years of data from between 1984 and 2000, and found that disability rates rose for all Americans younger than 60.

In the 30 to 49 age group, people who were disabled in their ability to care for themselves or perform routine tasks rose by 50 percent.

The biggest jumps occurred in claims related to musculoskeletal problems like chronic back pain and diabetes. Both are associated with overweight and obesity, and diabetes claims actually doubled over the study period.

The disability researchers said there will be enormous consequences on public finances if these trends continue. And unless we get a coherent public health plan for slimming America, these trends probably will.

Years Lost to Obesity

You know that being overweight can diminish your quality of life. But you may not have heard how it can diminish your quantity of life.

I'm Dr. Caroline Cederquist, giving you The Skinny on Your Health.

In simple terms, overweight people die younger. On average, they lose as many years to their excess weight as smokers lose to their cigarettes.

Among non-smokers who are clinically obese, women lose about seven years of life because of their excess weight, while men lose just under six.

That's six Thanksgivings, and who knows how many grandchildren born. That's six Superbowls they'll miss, six World Series they won't see.

The loss is much greater for overweight smokers. When you add smoking to the mix, the loss doubles, to around 13 years for both men and women.

That's 13 birthdays, 13 Fourth of July fireworks shows, 13 years of a special someone's school pictures.

And when you think about it that way, you see where those extra calories really count.

Sleep Apnea - While You Were Sleeping

Are you snuffling and snoring your way through the night?

I'm Dr. Caroline Cederquist, giving you The Skinny on Your Health.

If you have real trouble sleeping and you're also overweight, the chances are very good that you have sleep apnea. This is a breathing disorder in which the airway is obstructed when the mouth and throat relax during sleep. This can make breathing difficult and noisy.

But it's not really about the snoring. Apnea is like suffocating, over and over, all through the night. These episodes put the heart under terrible strain, and eventually cause it to enlarge and weaken.

And it's this weakening, rather than artery blockages, that is often the cause of heart failure in very overweight people.

There's a vicious circle at play here, because people with this problem often have a harder time losing weight, simply because of the oppressive fatigue caused by their sleepless nights.

Up to 95 percent of sleep apnea is thought to be related to obesity, yet sleep apnea often goes undiagnosed, so you may need to specifically ask your doctor about the disorder. But you can rest easy, knowing that even minor weight reductions can yield significant relief.

Obesity Redefined as Medical Issue

It's a "complex disease of appetite and metabolism, involving genetics, physiology, biochemistry, and the neurosciences, as well as environmental, psychological, and cultural factors."

I'm Dr. Caroline Cederquist, giving you The Skinny on Your Health.

That's obesity, defined by agencies like the Federal Trade Commission and World Health Organization.

Medicare isn't quite ready to acknowledge that definition. But they have at least decided to stop saying that obesity is NOT an illness.

That won't mean any immediate changes in coverage, but it does open the possibility that if medical research can identify effective treatments for obesity, Medicare might eventually cover them.

Up to now, opponents of such coverage have said its cost would be prohibitive, even though diabetes, arthritis, stroke and some cancers are all obesity-related.

But with those illnesses ever more common and costly, policy makers may have decided that an ounce of prevention might be a good idea, all around.