January 28, 2010
Moderately Overweight Elderly Live Longer?
Once you hit 70 is being overweight actually adaptive?
Adults aged over 70 years who are classified as overweight are less likely to die over a ten year period than adults who are in the 'normal' weight range, according to a new study published today in the Journal of The American Geriatrics Society.
It is hard to tease out the direction of cause and effect in a study such as this one. For example, a person who was overweight in their 50s and into their 60s could develop a disease that causes weight loss down to a "normal" weight by the time they hit 70. Then they die in their 70s from a disease that caused them to lose weight in their 60s. Not saying this result is explained by that possibility. But one must consider the possibility of disease causing weight loss years before diagnosis.
Researchers looked at data taken over a decade among more than 9,200 Australian men and women aged between 70 and 75 at the beginning of the study, who were assessed for their health and lifestyle as part of a study into healthy aging. The paper sheds light on the situation in Australia, which is ranked the third most obese country, behind the United States and the United Kingdom.
Obesity and overweight are most commonly defined according to body mass index (BMI), which is calculated by dividing bodyweight (in kg) by the square of height (in metres). The World Health Organisation (WHO) defines four principal categories: underweight, normal weight, overweight, and obese. The thresholds for these categories were primarily based on evidence from studies of morbidity and mortality risk in younger and middle-aged adults, but it remains unclear whether the overweight and obese cut-points are overly restrictive measures for predicting mortality in older people.
The study began in 1996 and recruited 4,677 men and 4,563 women. The participants were followed for ten years or until their death, whichever was sooner, and factors such as lifestyle, demographics, and health were measured. The research uncovered that mortality risk was lowest for participants with a BMI classified as overweight, with the risk of death reduced by 13% compared with normal weight participants. The benefits were only seen in the overweight category not in those people who are obese.
It is also possible that a moderately overweight person who develops a disease that causes weight loss in their 70s might live longer than a skinnier person because overweight person has stored fat to live off of while their appetite is poor due to disease. I've watched someone close to me die from cancer where the death came sooner due to loss of appetite.
Also possible the less healthy overweight folks die in their sixties leaving only the overweight folks with longevity traits.
And even more possible: the doctors of unhealthy overweight people scare them into shedding pounds in their 50's and 60's so they become unhealthy normal-weight folks in their 70's leaving more healthy overweight folks.
Not much guidance provided by this study.
There are too many causes for low BMI in the elderly to assume that it causes increased mortality.
For example, low weight elderly (who I assume are almost never dieters) suffer from chronic low-grade inflammation according to the following study:
"Elderly People With Low Body Weight May Have Subtle Low-grade Inflammation"
Also, several diseases, notably Alzheimer's, are preceded by appetite and weight loss.
It's been known for many decades that there is a mild correlation between overweight and health - insurance actuaries noted it long ago. And yet, lab animals consistently show a very strong cause and effect between weight and bad health: calories restriction extends life span, obesity greatly shortens it.
My guess: the average diet is low quality, so that only people who eat excess calories get enough micro-nutrients: vitamins, minerals, essential fatty acids, etc. Lab studies of calorie restriction ensure that the lab animals get sufficient micro-nutrients.
I think this kind of confounding is why researchers keep seeing epidemiological evidence for nutrition-related effects that don't hold up in controlled studies. For instance, it was observed that fat intake was correlated breast cancer, but the connection was disproved by controlled study. OTOH, it's clear that calorie restriction greatly reduces cancer, and obesity promotes it. So, fat intake is correlated with calorie intake, but fat isn't the real cause, it's the calories.
I'm sorry but BMI is a terrible measure for healthiness. Someone with a high BMI is just as likely to be more muscular than 'fat.' Another good indicator of health and longevity is grip strength (i.e. muscles). I would read this story indicative toward higher musculature, but as I said BMI is simply an extremely flawed measure.
Re the benefits of low-cal diets: I can't find the study now, but a pair of monkeys have been kept fifteen years or so on different diets, one normal and the other on "restricted" calories. The monkey on the low-cal diet is "healthier" but he looks and behaves as if he is absolutely miserable. I hope and pray that Mayor Bloomberg and the other health nannies don't get wind of this, as they will make New Yorkers go low-cal whether we like it or not!
The BMI standard is ridiculous in my view, and certainly a poor measure for older adults. I'm a healthy 73-year old female, 5 ft. 8 inches tall, 136 lbs. I hike, swim, work out with weights and wear a size 8 dress. My BMI, measured recently, was 30.5, which makes me "overweight." Should I be lucky enough to live longer than my peers they'll chalk up another one surviving due to excess poundage, I suppose.
Sorry. My mistake. Just realized that the 30.5 was my body fat measure, not my BMI. Maybe it's my mind that's going, not my body! Anyway, the numbers showed me as above the desired standard.
Also for a rich country, most people are moderately overweight by middle-age. This is true for every rich, white country at least - -not sure about Japan and Korea. The skinny people tend to be either the sick or the super health-nuts. And by the time you get into the 60s, and 70s -- the sick outnumber the health-nuts.
The developer of BMI cautioned it should only be applied to groups, never individuals.
Worse, the US "adjusted" the overweight BMI by five points to correspond with a W.H.O. study, rather than decades of research within the US. Japan also adjusted to the W.H.O. figures for it - but quickly returned to its own figures when doctors vociferously objected.
BMI measurement puts Marilyn Monroe for most of her film career in the "underweight" class, Michael Jordan (while he was playing) at the top end of "overweight" or even "obese" class[es]. Outliers? Perhaps. Or just normal ranges, confirming that BMI should indeed not be applied to individuals.
But then, I am in the position stated by actor Victor Buono - from memory:
"I am not overweight. I am underheight. My weight is perfect for a height of seven-nine."
lab animals consistently show a very strong cause and effect between weight and bad health: calories restriction extends life span, obesity greatly shortens it.
No. Tests on rodents show an increase in lifespan when calorie intake is restricted. The mechanism is not proven, but is probably because calorie restriction shuts down the reproductive system in rodents.
Tests on primates show calorie restriction associated with a decrease in deaths from vascular problems (heart disease, stroke) along with an increase in deaths from infection compared to a control group eating ad libitum. All-cause mortality showed no effect. No difference in lifespan.
The data are preliminary and more study is needed, as usual in these things, but the preliminary data don't show any reason to suspect calorie restriction increases lifespan in humans.
Could you show me the research you have in mind? From everything I've seen, calorie restriction has been tested on a very wide variety of animals, including a wide range of mammals, and has reliably reduced mortality and increased lifespan.
Preliminary results from the study at the U of Wisconsin indicated that this is likely to be the case for monkeys as well. http://www.nytimes.com/2009/07/10/science/10aging.html
I do find it the whole thing somewhat plausible. My father's generation are in their late eighties now, those who still survive. And one of his friends, a week or so younger than he, always carried a little extra weight. Much of it was muscle, but I think maybe a little fat too. Then, in his early eighties he contracted something in the hospital. It was touch and go for awhile, but he survived. He has looked almost skeletal since, given his large frame. My theory has long been that he used up his reserves fighting the disease, and if he hadn't had them, he wouldn't have survived and be nearing ninety now.
A strong social support network goes a long way towards enhancing our health and longevity. Perhaps the moderately overweight elderly tend to have stronger social support networks than do slimmer elderly. More friends equals more social functions equals more food consumption equals a heavier body weight.
To put it simply, this study probably doesn't mean pork out; it means increase lean muscle mass :)
Re: Anna: "I hope and pray that Mayor Bloomberg and the other health nannies don't get wind of this, as they will make New Yorkers go low-cal whether we like it or not!"
I'm all for a certain amount of rational libertarianism, but is anybody a fan of trans fat poisons? Even if we were to avoid trans fats by somehow never going out to restaurants to eat, we still pay for others' decreased health in the form of more costly healthcare insurance and a less productive economy.
"I'm sorry but BMI is a terrible measure for healthiness. Someone with a high BMI is just as likely to be more muscular than 'fat.' Another good indicator of health and longevity is grip strength (i.e. muscles). I would read this story indicative toward higher musculature, but as I said BMI is simply an extremely flawed measure."
I would tend to agree. We also have to factor that people who're considered overweight for reasons related to fat are likely to have a.) long periods of inactivity, probably sitting, which increases mortality, b.) probably spend their time indoors which decreases vitamin D and increases mortality, c.) likely to have at least some insulin resistance, metabolic syndrome which increases mortality d.) since as I've said we're talking the subset of BMI overweight related to fat, it is likely they don't watch the quality of their food intake(as health concerned individuals would eat to avoid excess fat, and would also try to be active to increase muscle mass and decrease fat.).
All those factors probably result in many fat related BMI overweight classified individuals dying early, leaving more of the lean muscle classified overweight by BMI in older subgroups. In other words at greater ages it is likely the overweight category contains a larger portion of individuals who fall into it due to lean muscle mass. Having more lean muscle tends to indicate a.) the bone is likely to be stronger as it responds to the additional force of the additional muscle and activity, b.) likely to eat better, c.) probably exposed to outdoor activities that increase vitamin D d.) Better cardiovascular health e.) the exercise required for having the additional lean mass means they get the benefits of exercise.
It would be interesting to divide this overweight category into predominantly lean mass vs predominantly fat mass categories and see how they fare in old age. Is the higher mortality of a less active, predominantly indoors, lifestyle enough to skew the results at later ages(i.e. change the composition of the overweight category enough towards the lean mass subgroup to account for the statistic result)?
True study, true conclusion, misleading message -It's not healthier for any adult to be overweight. This study underscores the limitations of BMI as an accurate predictor of disease for those in this age group. Our bodies produce about a mile of blood vessel for every extra pound of fat; producing a huge strain on your heart, while burdening other organs. So excess baggage at any age is dangerous. Here's why BMI is not my first chose for this age group.
1) We lose Height as we age: According to authorities, we lose about 4 tenths of an inch every 10 years, after the age of 40; but less lose occurs in those that remain physically fit. Research show our bones compress over time. The older we get, the more glaring the disparity between those that keep fit and those that don't ( this same study supported the value of exercise to reduce causes of mortality).
2): We lose Weight: Most of us lose muscle mass over time. Not all. Typically, it's not healthier at any age to be overweight, unless that weight is being carried by a leaner and more muscular frame. Our ratio of height to weight is effected by other factors the older we get. Like loss of hormones and nutrients, more pronounced in some than others. The key:
-Our ratio of muscle to fat ratio is one.
- Where it's sitting and how much is hanging on our gut is the other. The best predictor of disease from weight: belly fat. Short or tall, it's the amount of "toxic fat" we carry in our stomach.. The best test? The circumference of your waste. 25 pounds of toxic waste around your liver, kidney and stomach are as dangerous for a 165 pound person whose 5 feet tall as they are for a 200 pound person whose 6 feet tall.Best predictor of potential disease from fat? WC ( Weight Circumference). Breath out, use a tape on your skin, and simply measure. Over 35 inches in woman, and 40 inches in men, puts you in the potential danger zone.
BMI is a fine tool. But the best thing to measure weight wise for this age group, according to science, is your gut. For more information: Waist circumference and not body mass index explains obesity-related health risk:http://www.ajcn.org/cgi/content/abstract/79/3/379.
Randy Karp, author. Misinformed about Food