Archive for the ‘body mass index (BMI)’ Category

Exercise counts most for kids

Saturday, February 18th, 2012

thumbs up on this activity

In a previous post I mentioned former neighbors whose two boys had to run around outside for an hour a day (and they did spend most of that hour literally running), before they got any “screen time.” I thought that was admirable and noted both kids were slender.

Now I found an article in the February 15, 2102 issue of JAMA that confirms the wisdom of the approach my friends took toward this issue. A sextet of authors from the UK, Norway, Sweden and Canada published results for the International Children’s Accelerometry Database Collaborators (ICAD).

First I had to make sure what accelerometry meant in this context. The dictionary definition was only somewhat useful. It obviously refers to a gadget for measuring acceleration, but when I returned to a prior study  of 1,862 British children aged 9 or 10 published in 2009 in the American Journal of Clinical Nutrition, I learned it’s a very expensive and sophisticated gadget. My wife has a step counter that our local hospital seniors’ organization, the Aspen Club, gave her free. The device used in the large-scale research project, sold by a Florida firm, does lots more than just count steps. Among other thing it also monitors how much energy you expend and what your activity intensity has been. Of course the current model I found online costs $1,249, but there is a volume discount.

That earlier study concluded we need to get our youngsters really moving in order to “curb the growing obesity epidemic.”

The current paper offers a more nuanced viewpoint. It has a daunting title: “Moderate to Vigorous Physical Activity and Sedentary Time and Cardiometabolic Risk Factors in Children and Adolescents.”  The study looked at exercise levels and screen time in over 20,000 kids ages 4 to 18. Overall those who got more exercise improved all the risk factors measured: waist size, blood pressure, insulin levels, triglycerides and HDL cholesterol.

thumbs down on this one

Once levels of physical activity were factored in, sedentary time seemed relatively unimportant. But a smaller group, 6413 kids, was followed  for a little over two years and neither screen time nor exercise seemed important in changes in waist size, while kids who, at the start of the various studies, had bigger bellies, also had them later. I’d bet most of those were quite TV-addicted, since the paper warns that activity (or lack of activity actually) is often a clue to snacking and soft drinks.

I may show the short form of this paper to the principal of the nearby grade school I’ve mentioned previously. All those kids, starting in kindergarden, have a one-hour exercise period mostly spent running. I think it’s a school-district-wide program and just confirms what to me is common sense.

Lots of our youngsters are spending their days sitting in front of a screen of some sort instead of playing active games outdoors. Even in the age group followed in the recent article, a quarter of the kids were at least overweight; 7% were already obese. The average time for active play was a half an hour a day and the average for screen time was close to six hours a day.

I doubt we can totally reverse those numbers, but it’s a good idea.

Adults, obese and otherwise

Sunday, February 12th, 2012

PIck well and cut back your waste/waist

In my last post I explained the concept and the math behind the body mass index (BMI) approach to evaluating if your weight was normal or not (your BMI is very  well in synch with the most scientific methods of determining body fat percentages). Now I want to expand on that a bit  with some recent statistics and some thoughts on how we can lose weight if we need to. Unfortunately, some of us have lots of extra pounds we should shed if we want to have our best shot at leading long, healthy lives.

The Feb 1, 2012 issue of JAMA had a number of interesting articles on obesity. I’ve previously mentioned several on childhood and adolescent obesity; today I’d like to zero in on two whose focus is American adults.

Four CDC staffers, led by Katherine Flegal, PhD, published the most recent statistics from a recurring national survey with the daunting acronym NHANES. This national health and nutrition survey (the E stands for examination) started in 1971, but from 1999 on has been released results in two-year cycles. The current article from the National Center for Health Statistics, looking at the 2009-2010 NHANES data had a little good news and lots of bad news.

After 1980, until the turn of the 21st century, the prevalence (scientific term for percentage) of obesity in our population kept zooming up. Now it appears to have leveled off. I guess that’s something we should be happy about, except now over 35% of adults in this country are obese. Men and women have about equally high rates of obesity and men have caught up to women in this regard over the last twelve years. Some subsets, by sex and racial groups, are even more likely to be obese or very obese.

The worst news from this article was that no group–men, women, non-Hispanic whites, Hispanics or non-Hispanic blacks–had a decrease in the prevalence of obesity in this most recent data set.

So which exercise and diet should we try?

getting enough exercise is difficult when your joints hurt

Many adults report “No Leisure-Time Physical activity.” Overall, more of us are exercising, but the data vary from state to state. Those who have arthritis, fifty million in the US, need special attention or are even more likely to get no exercise. The CDC has worked with the Arthritis Foundation to develop ideas for this huge group. Going back to my review of articles on youngsters, I think for the rest of us, we could begin with simple steps, parking at the far end of the parking lot and substituting some walking for part of our screen time as two examples.

Harvard Medical School’s free online HEALTHbeat publication had a review of pros and cons of various diets in its Feb 7, 2012 edition. The bottom line still is if you want to lose weight, you must cut down on your calories. The Mediterranean-style emphasis on fruits and vegetables, unrefined carbohydrates, nuts, seeds and fish may be the most effective in reducing cardiovascular and diabetic risks.

My New Year’s Resolution is to keep my weight under 150 pounds. I have to work at it as I like to eat, but most of the time I’ve stayed away from splurges.

How about you?

 

JAMA

 

 

Adulthood: when your BMI is more important than your IBM (stock)

Thursday, February 9th, 2012

I do this at home, without clothes

In my last post I wrote about our upcoming generations and their obesity issues. Unfortunately, as you might have easily been able to predict, that carries over into adulthood. The same issue  (Feb 1, 2012)  of the Journal of the American Medical Association (usually called JAMA) had several articles on adults also. To begin with the National Health and Nutrition Survey (NHANES) looked at the body mass index (BMI) of men and women from 1999 through 2010.

“AARRGGHH” you say, “Why the hell should I care about whatever BMI is enough to try to understand it?”

Well, that’s a tough question, I admit. But BMI is the standard way of deciding if a person is too thin, normal, overweight or obese. So let’s give it a try.

Your BMI is a number calculated using your height and weight.  If you weight 250 pounds and you’re a seven-foot tall basketball professional center player, you’re unlikely to be obese. But if you’re five foot, six inches tall, and don’t exercise at all, like the adolescent I was reading about recently, you’re far too heavy. In the first case, the athlete has a lot of muscle, whereas the youngster is almost certain to be carrying around a lot of excess fat.

For a long time physicians just weighed their patients. That plus eyeballing their bodies in an exam room works for most people. Then along came the BMI as one way of getting a little more scientific. I looked online for the history of the use of body mass index as I suspected it was “invented” by a European (it was). It certainly seems to me to favor the metric system. There it’s easy to figure out your BMI; you divide your weight in kilos by your height in meters. It’s much more complicated using pounds and inches (BMI = weight in pounds divided by height in inches squared and that number is multiplied by 703) The CDC explanation of BMI is helpful and also supplies a “widget” you can download and a calculator if you just want to bookmark the website.

height counts, for adults too

So now you’ve (hopefully) figured out your own BMI; What does it mean and how reliable is it?

First the numbers: most people with a BMI under 18.5 are skinny, underweight. That probably excludes a whole passle of long-distance runners. Most people with a BMI over 18.5 and under 25 are in the “normal” weight category. I used the CDC calculator and my number is 20.5. Most whose magic number is 25+ and less than 30 are overweight and almost anyone whose BMI is over 30 is obese. The teenager I mentioned above has a BMI of 40.

Okay, you say. Now what do I need to do once I know what category I’m in.

I’d start with the eyeball test. Do you have a roll around the middle? In early 2009, weighing only three pounds more than I had for twenty years, I clearly did. I made up my mind to do something about that excess flab, knowing that fat in the belly also implies arteries that are narrowing down.

After losing thirty pounds and keeping it off, I bounced up after the Superbowl and went back on my diet, i.e., consuming fewer calories. I went to a meeting last evening; there were lots of goodies, but I ate only carrots and cucumbers. This morning I’m at 148.2 pounds, smack dab in the middle of the three-pound “ideal weight” range I decided on.

Harvard Medical School just published a piece titled “Choosing the diet that will work for you.” The central theme is cutting calories.