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Our Titanic Obesity Problem

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The annual "F as in Fat" report, issued jointly by the Trust for America's Health and the Robert Wood Johnson Foundation, is hot off the presses for 2013. The punch line is this seemingly welcome news: Obesity rates in the United States, overall, have leveled off. We'll get back to that, but let's establish some relevant context first.

In 2008, Shiriki Kumanyika and colleagues at Johns Hopkins published a paper in Obesity projecting that, should prevailing trends persist, by or about the middle of this century, every adult in the United States - but for a possible rounding error - would be overweight or obese. The analytical modeling was robust, the team of investigators highly accomplished and the effort both thoughtful and diligent. But even so, the projection was almost certainly wrong.

It was wrong for the same reasons that someone analyzing the sinking of the Titanic would have been wrong to project that eventually everyone would be soaked, if not drowned.

On the one hand, such an assessment would seem not only valid but virtually self-evident. After all, the Titanic was sinking, and there was nowhere else to go. Similarly, epidemic obesity has been akin to a sinking ship for years, and here, too, we are all in the same boat. Rates of obesity have been rising relentlessly for decades as more and more of us have, essentially, drowned in a roiling sea of diverse, energy-dense, nutrient-dilute, betcha-can't-eat-just-one kinds of foods; ever new variations on the theme of labor-saving technology; and the marketing dollars used to push these at us in wave after wave. More and more of us, and our children, have wound up in this obesigenic mess over our heads.

[Read: 10 Things the Food Industry Doesn't Want You to Know.]

But even on the Titanic, not everyone drowned - and some never even got dunked. The reasons, of course, had nothing to do with the severity of the problem - the ship did, indeed, sink. Rather, the reasons were idiosyncratic, representing some constellation of privilege and serendipity. The more affluent aboard the Titanic were on higher decks and had more time to await rescue before the rising waters overtook them. Some were perhaps fit and strong and better able to withstand elements of the evolving calamity. Some were maybe just lucky - in the right part of the ship at the right time.

Some similar constellation of factors may also defend against obesity. There is a well-established socioeconomic gradient; poverty is an obesity risk factor. So is lesser education, which in turn correlates with poverty. So is living in a neighborhood that offers lots of fast food but no supermarket selling fresh produce. This also, you guessed it, correlates with relative poverty.

[Read: Why We're So Fat: What's Behind the Latest Obesity Rates.]

But there are almost certainly other factors in play. As with surviving the Titanic disaster, good luck may play a role. Some people may simply wind up in circumstances that defend them against obesity. In some cases, it is personal commitment and resolve - and hard work. In some, there is defense at the level of genes. We are learning more and more about genetic variation - both our own and that of our resident microbes - with implications for energy balance and weight regulation. Some of us are genetically more disposed to gain weight, others less. Those at the extreme of the bell curve may find weight gain nearly impossible; most of us know a person or two like that, although they are very much in the minority.

They are very much in the minority with good reason. Throughout most of human history, calories were relatively scarce and hard to get, and physical exertion in the service of survival was unavoidable. In such context, genes for fuel efficiency - for gaining weight easily and losing it reluctantly - would flourish. Genes for the converse - losing weight easily, gaining it with difficulty - would sneak through on occasion, but rarely, as they would tend to confer a survival disadvantage.

In a world where physical activity is scarce and hard to get, and calories are unavoidable, those genes for energy inefficiency suddenly confer an advantage. But they confer it on the rare few who have carried such genes into the modern age, despite the disadvantage they conferred until now.

[Read: Accounting for Calories.]

For these and other reasons, it may simply be that there was never any real likelihood that absolutely all of us would get fat.

On the other hand, in 2010, the U.S. Ceners for Disease Control and Prevention projected that by or about the middle of this century, one in three of us would be diabetic - and that seems quite likely to come true should current trends persist. We have evidence to indicate we are well on our way already.

This projection by the CDC was no more robust than that of Kumanyika and colleagues, but it differed in one critical way: It was limited to the population already demonstrating its vulnerability. Predicting that more of those on Titanic's lower decks, where some were already drowning, would eventually drown would have been a safe, if grim, bet. Extending such projections to the less clearly vulnerable is where they tend to break down.

Projections about diabetes rates relate to those already showing signs of susceptibility in the form of prediabetes and insulin resistance. These, alas, are projections we can take to the bank. Or, more correctly, projections that will take everything out of the bank. The cost of all that diabetes will be staggering. The 2013 "F as in Fat" report includes projections of the future costs of obesity, even if the rates have stabilized but don't decline. The numbers are huge, and worrisome.

A 2012 projection by the CDC that obesity rates could rise to 42 percent by 2030 at a cost of some $500 billion is still potentially valid. The new "F as in Fat" report indicates an obesity rate above 40 percent among baby boomers in Louisiana and Alabama and above 30 percent in 41 more states. This may be a wave that has not yet crested. And, of course, even if obesity rates have stabilized, the high costs attached to current rates of obesity, and the chronic disease that follows in its wake, will extend long into the future.

It is in such context that we must consider and interpret the new "F as in Fat" report. As with recent news about childhood obesity rates declining in some sites, there may be some truly good news here. We can be thankful for evidence that ever growing attention to the threat of obesity, and increasingly diverse and rigorous efforts to contain it, may be working at last.

[Read: Michelle Obama Hosts Kids' State Dinner.]

But, it may also be that we are simply pushing up against the rafters. Rates of obesity had to level off eventually - the only question was whether it would at, or before, 100 percent. It appears to be before. That, in and of itself, is not exactly cause for celebration and certainly no invitation to complacency.

If the best possible news is true, and obesity rates have peaked and stabilized, we still have a whole boatload of trouble with which to contend. We have skyrocketing rates of severe obesity - the kind most likely to be very costly in both human terms and dollars. Just recently, we heard that when birth cohort is considered, the death toll of obesity is actually much higher than we previously thought - a peril looming for us baby boomers, among whom obesity rates are particularly high.

[Read: What is the World's 'Best Diet'?]

There is that rising diabetes rate on the horizon. There is a huge and growing burden of chronic disease globally. Obesity is a canary in the coalmine of that chronic disease - a harbinger of what is to come. A leveling off in rates of obesity, welcome news though it may be, does not suggest a leveling off in the rising rates of complications among those who have drowned in all those calories and are obese already. Recall that long after smoking rates dropped precipitously, the rates of lung cancer rose - because the damage had been done.

My assessment here may seem a bit gloomy to you, but there is method in my lugubrious madness. Obesity is all but entirely fixable. We are talking about a toll in both years from life and life from years, that we could avoid with systematically better use of our feet and our forks.

Strategies to get us there from here are accessible to us. They are hard, perhaps, but not complicated. We could immunize ourselves and our children against obesity at the level of our culture. But we still have a long way to go.

We won't get there if we decide prematurely that the crisis is over. Recent encouraging news about obesity rates indicates that if we take arms against this sea of troubles, we have some hope that by opposing them, we may eventually end them. It does not suggest that the end is in sight.

It seems that not quite everyone will drown in calories. But millions already have, and millions more are still in over their heads. Our troubles with obesity remain titanic in scope - and a long way from over.

[Read: Recipe for Health.]

Hungry for more? Write to eatandrun@usnews.com with your questions, concerns, and feedback.

David L. Katz, MD, MPH, FACPM, FACP, is a specialist in internal medicine and preventive medicine, with particular expertise in nutrition, weight management, and chronic-disease prevention. He is the founding director of Yale University's Prevention Research Center, and principal inventor of the NuVal nutrition guidance system. Katz was named editor-in-chief of Childhood Obesity in 2011, and is president-elect of the American College of Lifestyle Medicine.

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