Can You Be Fit and Fat?

Many of us would describe the ideal runner's body as lean, lanky, lithe. But then someone who is none of those things blows past us in a 5-K, leaving us questioning what "fit" really looks like. Some doctors say people who are overweight (body-mass index, or BMI, of 25 to 29.9) or obese (BMI above 30) will face health issues, regardless of how often--or fast--they run. But some studies show that heavy people who exercise can be cardiovascularly healthy and may live longer than their sedentary but skinny peers.

We asked two experts to, ahem, weigh in. Glenn Gaesser, Ph.D., director of the Healthy Lifestyles Research Center at Arizona State University, says you can be fit and fat. Amy Weinstein, M.D., M.P.H., an assistant professor at Harvard Medical School who studies the impact of obesity and exercise on disease, disagrees. Here's why.

Is it possible to be overweight and healthy?YES

Virtually every weight-related health problem can be greatly improved or cured with a moderate level of exercise, even if you're overweight. The amount of exercise necessary to achieve a fitness level that greatly reduces disease and mortality risk is the equivalent of brisk walking for 30 minutes a day, five days a week, or running 20 to 30 minutes a day, three days a week.

NO
Based on research I've seen and studies I've performed, it appears that physical activity cannot completely reverse the ill effects of carrying excess weight on diabetes and cardiovascular disease. The reason for this is unclear. There may be hormones and proteins that regulate weight and affect chronic diseases, which physical activity cannot reverse.

But can a butterball really outrun a lean machine?YES

It's possible for a heavier runner to be faster than a thinner runner if the heavier runner has the necessary ingredients for better endurance: higher VO2 max, higher lactate threshold, and better running economy. Genes play a huge role as well, as does experience.

NO

Well, sure, it's not impossible. But a person who is overweight would be faster if he lost weight. A loss of about two pounds will theoretically increase speed by about a meter per minute of running. So if a runner runs a 5-K in 20 minutes, a two-pound weight loss would make him five seconds faster overall.

Do heavy runners get injured at the same rate as thin runners?NO

Being overweight increases your risk of arthritis. Research shows that obese people have almost three times the risk of arthritis in the knees. So it would make sense that heavy runners are at a higher risk of injuring their joints.

Should runners disregard age-related weight gain?YES

To control your weight as your metabolism slows down, you probably have to double your exercise. After age 40, you'd need to run about two more miles per week, each year, in order to maintain your weight. So if you are running 25 miles a week at age 40, you'd have to do 27 miles at 41, 29 miles a week at 42, and so on. That might be more than most people are willing to do. That's why I promote physical activity for health and not for losing weight, because it takes a lot. If your weight is creeping up but your cholesterol and blood pressure stay in the healthy range, I wouldn't worry about it.


Source:Runners World 4/30/11

Obese with strong heart beats those thin and weak

NEW YORK (Reuters Health) - For overweight people with heart disease, improving their physical fitness could pay big dividends.

A new study has found that fitness, not body weight, is a more important predictor of whether people with clogged blood vessels in their heart will die in the relatively near term.

Being overweight, or even obese, but having a heart that could tolerate heavy exercise was markedly better than being a lean person who panted from walking up a hill.

Not surprisingly, the study also showed that obese heart patients who were least physically fit, and those with large amounts of fat concentrated around their hips and abdomen, were much more likely to die during the 14-year study period compared to their fitter, more slender peers. The combination of poor fitness and that kind of so-called "central obesity" was even more dangerous, raising the risk for death roughly sevenfold, the researchers said.

"The bottom line here is that fitness modulates the prognosis in patients with coronary artery disease according to their body weight," study leader Dr. Francisco Lopez-Jimenez, a heart specialist at Mayo Clinic, in Rochester, Minn., told Reuters Health. "To have a low fitness and to have central obesity seems to be a pretty bad combination."

For the new study, published in the American Heart Journal, Dr. Lopez-Jimenez and colleagues studied 855 men and women enrolled in a cardiac rehabilitation program. In the past, all of them had either had heart attacks, or bouts of severe chest pain related to heart problems. Some had undergone medical or surgical procedures to help unclog the blood vessels in the heart.

To assess patients' fitness, doctors had them walk on treadmills. They were each assigned a score based on the distance they could walk, and their ability to take in oxygen while exercising - both key aspects of physical fitness.

The researchers used body-mass index - a ratio of height to weight - to determine whether patients were overweight or obese.

Patients who were fit and relatively thin had the lowest odds of dying in the study period and constituted a "control" group. Fit but overweight patients were about twice as likely to die, while those who were fit but obese had three times the risk of death compared to the fit and thin control group.

Things got more complicated for the unfit. Patients with poor fitness scores who were overweight were nearly 7 times more likely to die during the study compared to the control group. But normal-weight people who were unfit were nearly 10 times more likely to die, the researchers found.

In other words, as long as a person with heart disease stays active, being obese-at least according to their body mass index-does not seem to make their prognosis worse. On the other hand, having too much abdominal fat is a problem even for people who can withstand a lot of exercise.

"You are better off if you are fit, and you are better off if you have a shorter belt," said Eric Ravussin, an obesity expert at the Pennington Biomedical Research Center in Baton Rouge, LA.

Ravussin offered several explanations for why obesity did not seem to have the impact one might expect. Obese people typically go to the doctor often, and thus are more likely to be tested, and treated, for high cholesterol, a leading risk factor for heart attacks and strokes, he said. The new study did not look at how many cholesterol-lowering medications patients were taking.

Compared to thin people, the obese have more energy reserves to help them weather serious illnesses, Ravussin noted. Also, studies have shown they appear to be better able to suppress inflammation linked to heart and vessel damage - although the reasons for that aren't clear.

Whatever the case, Lopes-Jimenez said, the lesson for patients is clear: try to improve your physical fitness. "It is much easier to become fit than it is to become slim," he said. "Anybody who has gone into an exercise program would agree with that."

SOURCE: Reuters, Adam Marcus 3/31/11: bit.ly/i25TCj American Heart Journal, March 2011.

Is Fitness in the Genes?

Why do some people respond to an aerobic workout routine by becoming incredibly fit, whereas others who exercise just as hard for months end up no fitter than when they began?

That question has bedeviled countless people who’ve started exercise programs. It has also motivated a major new study of the genetics of fitness. Scientists long have known that when any given group of people faithfully follows the same aerobic workout routine, some increase their cardiorespiratory fitness substantially, while an unfortunate few seem to get no benefits at all. But what, beyond the fundamental unfairness of life, makes one person’s body receptive to exercise and another’s resistant? According to the new study, which will soon be published in The Journal of Applied Physiology, part of the answer may depend on the state of specific genes.

For the study, researchers from the Pennington Biomedical Research Center in Baton Rouge, La., and other institutions examined the genomes of 473 healthy white volunteers. All were part of the Heritage Family Study, an ongoing (and multiethnic) examination of exercise genetics that already has provided reams of epidemiological information about whether various exercise traits tend to run in families. (It turns out that many do, including the basic drive to exercise at all.) But neither the Heritage Study nor any other experiment to date had identified the specific genes that might be associated with a person’s physical response to exercise.

The researchers looked at 324,611 individual snippets over all. Each of the volunteers had already completed a carefully supervised five-month exercise program, during which participants pedaled stationary bicycles three times a week, at controlled and identical intensities. Some wound up much fitter, as determined by the increase in the amount of oxygen their bodies consumed during intense exercise, a measure called maximal oxygen capacity, or VO2 max. In others, VO2 max had barely budged. No obvious, consistent differences in age, gender, body mass or commitment marked those who responded well and those who continued to huff and struggle during their workouts, even after five months.

But there was a divergence in their genomes. The researchers identified 21 specific SNPs, out of the more than 300,000 examined, that differed consistently between the two groups. SNPs come in pairs, since each of us receives one paternal copy and one maternal copy. So there were 42 different individual versions of the 21 SNPs. Those exercisers who had 19 or more of these SNPs improved their cardiorespiratory fitness three times as much as those who had nine or fewer.

One SNP in particular, located on a gene known as ACSL1, seemed especially potent, possibly accounting for as much as 6 percent of the difference in response among people, a high percentage by the standards of genomewide association studies. This gene already has been shown to play a role in how the body metabolizes fats, which might partly explain why it also affects exercise response. But, said Claude Bouchard, who holds the John W. Barton Sr. Endowed Chair in Genetics and Nutrition at Pennington and was lead author of the study, “far more research is needed before we can say” just how any particular gene influences the body’s response to aerobic exercise, let alone what additional genes might be involved in that response.

Still, the findings, preliminary or not, raise several intriguing concerns. How, for one, can any of us tell if we harbor the ideal SNPs for a robust aerobic response to endurance exercise? And if it turns out that we don’t carry those advantageous snippets of genes, can we take to the couch, since our fitness levels won’t budge much even if we dutifully pedal or run?

“It will be years, if ever,” said Dr. Bouchard, before gene tests exist that can reliably separate high and low responders. Even if and when such tests become available, he continued, the results will not constitute an excuse for skipping workouts. “There are countless other benefits provided by exercise,” he said, apart from whether it raises your VO2 max. “Exercise can reduce blood pressure and improve lipid profiles,” he said. It can better your health, even if, by certain measures, it does not render you more aerobically fit.

Source: Gretchen Reynolds, New York Times, March 16, 2011


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