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The obesity paradox: Can being overweight be beneficial?

The obesity paradox: Can being...
New studies rekindle debate over whether obesity can be beneficial in some health situations
New studies rekindle debate over whether obesity can be beneficial in some health situations
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New studies rekindle debate over whether obesity can be beneficial in some health situations
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New studies rekindle debate over whether obesity can be beneficial in some health situations

Over 15 years ago, a strange counter-intuitive bit of data was identified in patients undergoing hemodialysis for chronic kidney disease. Across several studies, overweight or mildly obese patients were displaying greater survival rates than those with healthy weights. The phenomenon was dubbed the "obesity paradox" and for well over a decade scientists have debated what could be causing it. Several new studies presented recently at the European Congress on Obesity have added further weight to the hypothesis of an obesity paradox, finding several strange correlations between obesity and survival rates across a variety of conditions.

The first study looked generally at patients admitted to hospital for an infectious disease. Tracking more that 18,000 patients admitted to hospitals in Denmark over a four-year period, the study found that within 90 days of discharge those patients of a normal weight displayed a significantly higher chance of dying when compared to both overweight and obese patients.

Two more studies presented at the conference examined mortality rates from patients admitted to hospitals for pneumonia and sepsis. Both studies examined large banks of data tracking admissions from over 1,000 US hospitals.

The pneumonia study, which included data from 1,690,760 hospitalizations, found that obese and overweight patients were between 20 and 30 percent less likely to die from the condition than those of normal weight. The sepsis study impressively gathered data from 3.7 million hospital admissions and found obese and overweight patients were around 20 percent more likely to survive following admission than patients of normal weight.

The final study was much smaller than the others but was more interested in investigating a specific potential hypothesis that could help explain the obesity paradox. This research examined the rate of muscle wasting in critically ill patients admitted to intensive care. Only 26 patients were studied, but the results saw the obese subgroup displaying notably different muscle wasting patterns than the non-obese group.

The hypothesis is that when a critically ill body enters an acute stage of illness it moves into a phase called hyper-catabolism. This phase finds the body rapidly searching for extra fuel for energy production in vital organs. The state can often lead to muscle wasting as the body breaks down that tissue for energy.

This study found that obese patients in this context displayed a slower rate of muscle wasting when compared to non-obese patients, and also a higher muscle quality index. In conclusion, the authors of the research suggest that, "Critically ill patients with obesity seem to have higher muscle quality, as measured by ultrasound at the point of admittance to intensive care compared to non-obese patients. This might be the metabolic protective shield also described as the 'obesity paradox'."

None of this research at all suggests general recommendations for healthy body mass indexes to be changed, as an enormous body of data still exists linking obesity to increased risk of a number of illnesses. But, the strange idea of an obesity paradox still remains present in some observational studies, and any causal connection is still frustratingly unexplained.

David Carslake from the University of Bristol says this new research doesn't necessarily imply a causal link between obesity and higher survival rates for the specific conditions but instead suggests there may be a variety of unmeasured factors that are causing these paradoxical results.

"First, unmeasured factors such as smoking behavior or other diseases could cause both a reduction in BMI and increased mortality," says Carslake. "The authors took steps to adjust for these, but they can never be fully accounted for by the methods they used. Second, it's possible that overweight and obese people get admitted to hospital more readily with less severe cases of sepsis, infection or pneumonia. This is a risk whenever analyses are restricted to specific patient groups, and in this case could give a spurious impression that high BMI was protective."

Other research also suggests that by simply measuring obesity by body mass index can result in skewed and questionable results. A 2013 study suggested that when other obesity-related data points are taken into account, such as waist circumference (WC) and waist to hip ratio (WHR), any indication of the obesity paradox tends to disappear from a study's results.

Anne Peeters, from Deakin University, has gone as far as suggesting that journals should reject articles that imply the existence of an obesity paradox due to fundamental flaws in the correlation between body mass index and mortality and it may give people a false belief that obesity can be beneficial.

Despite these new studies again raising the controversial specter of an obesity paradox, no one is suggesting gaining weight improves the odds of a healthy outcome for any illness. Ultimately, any positive causal connection between obesity and survival in a specific scenario is outweighed by the overall volume of data linking obesity with a great number of terminal illnesses.

The new studies are currently unpublished and yet to be peer reviewed but were presented at the recent European Congress on Obesity in Vienna, Austria.

Sources: European Congress on Obesity via SciMex

8 comments
Daishi
I think the key term here is "mildly obese". For a man of average height (5'10 or 178 cm) from 130 to 170 lbs (77kg) is normal. From 170 to 210 lbs (95 kg) is overweight. Anything over is obese. The BMI scale is stricter than most humans on the issue. For an adult male I would consider 200 lbs closer to "normal" than 130 lbs. Many of the people they consider "mildly obese" probably look mostly normal to me especially since the BMI scale doesn't measure body fat percentages. Maybe measuring body fat percentages along with BMI for patients would add less ambiguity to these studies.
Asgard
Translated: Chubby good. Really fat or really skinny not good. I've seen other studies showing it's best for seniors to have some padding on them. Still, like everything, moderation is everything. Get that heart rate up and pumping a few times a week at least.
Nik
Doctors are incredibly reluctant to let go of an idea regardless of any indications that suggest that the idea may be wrong. eg, ''Washing my hands before operating on a patient is rubbish,'' ''Nothing can live in the stomach because its too acid,'' but bacteria does, so thats now abandoned, but it took a doctor TEN years to get anyone to heed him, and ''the lungs are sterile,'' but they are not. Also in the fifties, the recommended cure for ENT infections, [ear nose and throat] was to amputate the tonsils. Thats like saying, ''Oh you have an infection on your leg, then we'll just cut your leg off, and that will cure it!'' So, now they'eve formed the idea that being 'overweight' is unhealthy, no evidence on earth will convince them otherwise, yet. One story reported that a doctor told his patient with a high cholesterol, level he would die prematurely if he didnt reduce it. The patient didnt reduce it, but he out lived his doctor who was younger the he. However, what is overweight? It must vary from person to person. no 'one weight' can suit everybody. I suppose, that ones lifestyle is more significant than being mildly overweight, when it comes to survival, after all storing energy reserves in the form of fat IS a survival tactic, which is used by many animals, all their lives, to survive the winters.
Kiffit
It seems to me that if a person becomes seriously ill for any reason, it puts enormous stress on the body at the same time that it loses its appetite for food. That is a recipe for losing weight rapidly. And if one does not have the fat to cover the deficit, the body takes down other tissue instead. That is what fat storage is for; i.e., for when there isn't enough food intake and/or body systems are having to deal with abnormal/exhausting demands
lon4
Reminds me of the lyrics in that song from the '70's "Fat people are happy people." And if you're happy, you probably won't get ill as often.
Saigvre
Science Media Exchange! So 'scimex' covers Australian and New Zealand. Instead of being an antiseptic lubricant for science-ing things. Already the European Congress on Obseity (actually in Vienna, Austria...[checks to see if misread 'Austria and New Zealand;' nope]) is more palatable. This is a fine upbeat sort of news to bring when pondering patients 20-80% over weight (and Beyond! Mild nothing.) It was always an advantage swimming the English Channel, and mountain climbers seem to have the same fat plus in crag grips used as pitons, but this seeming 20-30% advantage makes 'browning' fat look special (well...offers it good light?) It reminds me of the House M.D. bit where the adult kid had formic acid poisoning him only affect him once the fat he was packing away while weathering it had to be burnt. It also reminds that dialysis and clinical care are still not yet a universally great place to pack in workouts, rapid recovery, hyperbaric oxygen treatments, adaptive fittings, lucid dreaming, boutique shopping etc. Getting there!
guzmanchinky
The only true test is a floating fat test. All the other BMI stuff is wildly misleading on the verge of being criminally so (as in insurance rates based on it, people dying to be the right BMI, etc).
rude.dawg
guzmanchinky is correct Just because a person is "overweight" doesn't mean they're obese. Muscle weighs more than fat. Simply looking at weight-to-height rations (BMI) without analysing muscle-to-fat ratios really doesn't help much. https://www.livestrong.com/article/429402-how-to-calculate-your-muscle-to-fat-ratio/