Big Belly, Bad Brain

by Lou Schuler on Mar 27, 2008 9:11 AM EDT in News

Rehan Jalali sent along this article about the brain-belly link:

Having a large gut in midlife increases the chance of dementia in old age, according to new research published Wednesday that suggests that abdominal fat is a bigger risk factor than even family history.

The study of 6,583 adults found that people with the highest amount of abdominal fat between the ages of 40 and 45 were about three times more likely to develop dementia than those with the lowest amount.

By contrast, people who have parents or a sibling with Alzheimer's face twice the risk of developing the disease.

The report in the journal Neurology was the latest to show that belly fat can pose serious health risks, even for those who are not obese. Previous research has shown that people with large abdomens face a greater chance of diabetes, stroke and heart disease.

They determined belly fat by measuring abdominal diameter -- sort of like phrenology for the midsection. Those with an abdominal diameter greater than 25 centimeters -- just under 10 inches -- were in the highest-risk category.

The researchers also looked at the combination of belly fat and body weight, using body-mass index to determine if participants were overweight or obese:

Those who were overweight and had a large belly when measurements were taken were 2.3 times more likely to develop dementia in old age than those who had a healthy weight and belly size when they were younger.

The researchers categorized subjects as overweight if they had a body mass index of 25 to 29.9. The index, also known as BMI, is a ratio of height and weight. For example, a man who is 6 feet tall and weighs 184 pounds is overweight.

People who were obese -- with a BMI greater than 30 -- and had a large belly in middle age were 3.6 times more likely to develop dementia later in life than those whose weight and belly size had been in the healthy range.

This line of research isn't entirely new; Rachel Whitmer, the lead researcher, has been looking at it for years. Here's what she said in a study published last year:

Our work has shown that both obesity and overweight, as measured by body-mass index and skinfold thickness, in middle age are strongly associated with an increased risk of all-cause dementia, Alzheimer disease, and vascular dementia, independent of the development of diabetes and cardiovascular-related morbidities.

By coincidence, I've been looking through a lot of studies on fitness, strength, and all-cause mortality, and one of the most interesting findings is that the healthiest weight for longevity seems to be one that would put you in the "overweight" category, but stopping short of "obese."

So if you're a guy who's six feet tall, you're technically at a "healthy" weight if you weigh 180 or less. But being "overweight" -- weighing 185 to 200 pounds -- might actually be healthier, assuming you'd have equal amounts of physical activity at either weight. If you went up to 220 pounds, you'd be right at the edge of obesity.

I'm not saying it's a good idea to pack on pounds if you're healthy and active at your current weight. But it isn't necessarily a good idea to lose weight if you're strong, fit, and active despite being "overweight" according to BMI.

I should also point out that this was a pretty shallow look at the research on my part -- I was mostly looking at abstracts, and only did line-by-line readings of a couple of the full studies. In some cases, the apparent advantage of being overweight disappeared when the researchers adjusted for more variables.

But two big ideas seemed pretty clear to me:

At any weight, it's better to be stronger.
No matter how strong and muscular you are, it's not a good idea to carry around so much extra weight that you end up in the "obese" category.

And no matter how strong you are, or how much you weigh, I think you have to pay attention to that all-important waist measurement. If your waist is bigger than your hips, you need to shrink it.

How? Personally, I don't think you can go wrong with this or this.

Thursday brain meat

Another new study suggests older women need more protein to build or maintain muscle. (Hat tip: Anthony McInnis.)
Just when you think you can't possibly have a lower opinion of tobacco companies ...

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Comments

Oy! The BMI again!

Why is it that researchers use the BMI for any kind of scientific prognosis and analysis when it is of such low value as an indicator? Did their funding run out when they got to the caliper purchase? Or is it that the assessing lean mass / fat percentage of their subjects would be too time consuming when they'd rather be home and watch 'Friends' re-runs?

When I had my body fat % checked last, I came in at 25,8%. Yeah, I'm fat. Yeah, I'm overweight. That's why I'm reading your blog and buying your books. In any event, that put my lean mass at 200 lbs. So even if you were to boil all the fat away from my carcass, I'd still be, according to the BMI (36,6), clinically obese.

Let's assume the trainer at the gym didn't know her calipers from a pair of tweezers and grossly underestimated my body fat, and that I'd actually be at 35%. Only if I would then lose all of it would the resulting perfectly lean mass (176 pounds) put me in the 'Normal' category. Of course, I'd be dead, as the human body can't function with 0% body fat, but at least I'd fit within the "standards". So, please, no more BMI studies. Please.

by Carl on Mar 27, 2008 2:45 PM EDT 0 recs

I appreciate your frustration ...

... but remember, these are big studies, looking at thousands of people over the course of several decades. BMI may be meaningless for individuals, but for these big observational studies (as opposed to smaller intervention studies in which they get study subjects to do something specific that's different from what they normally do, and then compare them to a control group), it's a pretty good stand-in for fitness status and activity level.

Remember, these are old people, and it's unlikely that many of them are lifters or runners. In a large population, the leanest ones according to BMI are probably the ones who get the most leisure-time physical activity.

There might be a few lifters in the group carrying a lot of muscle mass who get classified as obese, as well as an overweight runner or two, but for the most part you're looking at people who haven't done a lot of deliberate interventions to change their body size and health status.

Dr. Whitmer wrote in another study that a big problem with studying Alzheimer's patients is that they tend to lose a lot of weight after they get sick. So you have to go back a couple of decades to figure out how big they were before they developed dementia.

So the researchers can't go back in time and take body-comp measurements that no one would've thought to take decades ago, or to ask questions about exercise when there was no consensus on whether that was important.

by Lou Schuler on Mar 27, 2008 4:21 PM EDT up 0 recs

You're right, of course

However the Kaiser study's measurements were not done a posteriori, but when the patients were in middle-age. They didn't have to ask their fragile and senile patients about their body weight when they were young, as Kaiser already had the data. And back between '64 and '73, which is when the data regarding body composition was collected, scientists could have been a bit more thorough if the goal was to use body composition as a data point for health outcomes 30 or 40 years down the line. I'm no epidemiologist but it seems to me that their original dataset's quality is a bit weak to make such sweeping conclusions.

Or maybe I'm quibbling because I'm tired of being lumped in the 'morbidly obese' category when I'm just 'festively plump' (or delusional) :-)

by Carl on Mar 28, 2008 10:39 AM EDT up 0 recs

And what does this really prove ?

BMI doesn't measure anything meaningful. Did they look at the diets of these people ? What were the exercise patterns ? What was their level of fitness ? Did they have undiagnosed high blood pressure which is common with overweight people and certainly leads to a huge variety of ailments.

by slevan on Mar 27, 2008 2:53 PM EDT 0 recs

see above

We can't know things about these patients that a researcher wouldn't have thought to ask decades ago.

But I don't think the conclusions are in any way out of step with current thinking about the brain-body connection.

by Lou Schuler on Mar 27, 2008 4:24 PM EDT up 0 recs

stomach vs. brain

Okay, this may be a stupid question (hey, we can't all be smart), but anyway: let's say you were a bit tubby of stomach in your 30s and 40s, but then you got religion and Lou's books and you lost a fair bit of belly flab in your late 40s and stayed in a decently trim (.9 or better waist-hip ratio? the number on Today Show this a.m.) for the next couple decades. Did your youthful stomach do irreparable future damage to your future oldster brain? You know, like how sunburns in childhood lead to skin cancers in adulthood, even if you finally started using sunscreen?

by pak202 on Mar 27, 2008 3:47 PM EDT 0 recs

You can improve your fitness levels at any age

And where the body goes, the brain follows.

I didn't have to study neurology to get my journalism degree, but from what I've read as a layman, there seems to be a consensus developing that the brain remains somewhat malleable throughout life.

We know that performing complex mental and physical tasks gives the brain new and better nerve cells, just as inactivity or a lack of mental stimulation can cause the brain to shrink and nerve endings to shrivel up.

So I vote for you getting a do-over, flab-wise.

by Lou Schuler on Mar 27, 2008 4:30 PM EDT up 0 recs

Huh?

If I am doing my geometry correctly, C=pi x D; that means a waist over 31.4 inches puts you at risk???
I'm 56..I'm not sure I know anyone with a waist smaller than 33-34.

by siliconwarrior on Mar 31, 2008 6:09 PM EDT 0 recs