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Dean Pomerleau

More Evidence "It's the Diet/Lifestyle, Stupid", Not the Calories

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Al posted a new study [1], that appears to me to support the theory I've been promulgating for a while that what's important for health and longevity is the quality of one's diet and lifestyle, rather than the quantity of calories one eats.

 

The study followed over 90,000 postmenopausal women for about 13 years to see how the baseline quality of their diet (as quantified by 4 popular dietary quality metrics) impacted subsequent mortality. The dietary quality metrics were designed to gauge how well the women adhered to commonly-accepted 'good' dietary patterns, like following a Mediterranean Diet, or a DASH-like diet. All four shared much in common (emphasize fruits & vegetables, whole grains, avoid red & processed meat, etc.), and fortunately all four resulted in similar outcomes in this study, so I'll collapse all four in my brief discussion of the results below into a single notion of a "good diet".

 

What they found was the women who had the best diet (i.e. were in the highest quintile of 'good diet' score relative to lowest quintile) had about a 20-25% lower risk of dying during the 13 year follow-up period. They also had a lower BMI (25-26 vs. 28-29) although weren't especially slim, and the exercised more than the women who ate the crappiest diet, although the researchers attempted to factor out BMI, exercise, and calories (see next point) from their statistical analysis to focus on the link between diet quality and mortality. On average the women who were eating the best diet and hence were healthier & longer-lived didn't report eating any fewer calories than the women eating the crappiest diet (although as we know food frequency questionnaires are fraught with difficulties...), they were just eating healthy foods rather than unhealthy ones.

 

In short, this is yet one more study showing that dramatic improvements in health/longevity, on par with what we hope to achieve via CR, seem to be attainable by following a healthy obesity-avoiding diet & lifestyle, but without calorie restriction.

 

--Dean

 

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[1] Comparing indices of diet quality with chronic disease mortality risk in postmenopausal women in the Women's Health Initiative Observational Study: evidence to inform national dietary guidance.

George SM, Ballard-Barbash R, Manson JE, Reedy J, Shikany JM, Subar AF, Tinker LF, Vitolins M, Neuhouser ML.
Am J Epidemiol. 2014 Sep 15;180(6):616-25. doi: 10.1093/aje/kwu173. Epub 2014 Jul 17.
PMID: 25035143 Free PMC Article
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157698/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157698/pdf/kwu173.pdf

Abstract

Poor diet quality is thought to be a leading risk factor for years of life lost. We examined how scores on 4 commonly used diet quality indices-the Healthy Eating Index 2010 (HEI), the Alternative Healthy Eating Index 2010 (AHEI), the Alternate Mediterranean Diet (aMED), and the Dietary Approaches to Stop Hypertension (DASH)-are related to the risks of death from all causes, cardiovascular disease (CVD), and cancer among postmenopausal women. Our prospective cohort study included 63,805 participants in the Women's Health Initiative Observational Study (from 1993-2010) who completed a food frequency questionnaire at enrollment. Cox proportional hazards models were fit using person-years as the underlying time metric. We estimated multivariate hazard ratios and 95% confidence intervals for death associated with increasing quintiles of diet quality index scores. During 12.9 years of follow-up, 5,692 deaths occurred, including 1,483 from CVD and 2,384 from cancer. Across indices and after adjustment for multiple covariates, having better diet quality (as assessed by HEI, AHEI, aMED, and DASH scores) was associated with statistically significant 18%-26% lower all-cause and CVD mortality risk. Higher HEI, aMED, and DASH (but not AHEI) scores were associated with a statistically significant 20%-23% lower risk of cancer death. These results suggest that postmenopausal women consuming a diet in line with a priori diet quality indices have a lower risk of death from chronic disease.
Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

KEYWORDS:

diet; diet quality indices; mortality risk; postmenopausal women; prospective cohort study

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In short, this is yet one more study showing that dramatic improvements in health/longevity, on par with what we hope to achieve via CR, seem to be attainable by following a healthy obesity-avoiding diet & lifestyle, but without calorie restriction.

 

I donno. Lower BMI amongst older women in the study seems at least suggestive that they also ate less food.

 

...

(although as we know food frequency questionnaires are fraught with difficulties...), they were just eating healthy foods rather than unhealthy ones.

And "...having a high BMI is associated with underreporting of food intakes, and the foods most underreported are those that dietary guidelines advise populations to consume in moderation (e.g., high-fat, high- sugar, and high-calorie/low–nutrient-dense food)..."

 

Quantity and quality both seem important.

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Sthira,

 

I donno. Lower BMI amongst older women in the study seems at least suggestive that they also ate less food.

 

Granted, they may have ate less food - that's why my statement included the clause "obesity-avoiding". They also reported exercising twice as much as the poor eaters - which may have accounted for their lower BMI.

 

But whatever the cause, with an average BMI of ~25.5, the women eating the healthiest diet certainly weren't doing significant CR.

 

So perhaps my statement should have been:

 

"In short, this is yet one more study showing that dramatic improvements in health/longevity, on par with what we hope to achieve via CR, seem to be attainable by following a healthy, obesity-avoiding diet & lifestyle, but without significant calorie restriction."
 

--Dean

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Thanks, Dean,

 

As the title of my original message inferred: "Healthy-diets, BMI, Mortality", the subjects with the lowest BMI, <25, vs those overweight or obese, fared better on the healthy diets:

 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157698/table/KWU173TB5/

 

See the DASH dieters, for eg.

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As the title of my original message inferred: "Healthy-diets, BMI, Mortality", the subjects with the lowest BMI, <25, vs those overweight or obese, fared better on the healthy diets:

 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157698/table/KWU173TB5/

 

See the DASH dieters, for eg.

 

Al (and others) just some friendly advice. We're not interested in clickbaiting here - where a vaguely-worded but intriguing statement forces readers to click on a link in order to learn more.  If you really want to be helpful when you post, you should provide more useful details than "See the DASH dieters, for eg".

 

Something like:

 

In the study we're discussing (PMID 25035143) women eating a good diet and with a BMI < 25 had a very modest survival advantage relative to women eating a good diet with a BMI 25-30, as illustrated in the highlighted elements of the table below:

 

wJROngr.png

 

How far below a BMI of 25 the women in the "BMI < 25" groupings had is unspecified in the paper, but is unlikely on average to be too far below, I expect. In fact, the reason I didn't mention BMI in my original analysis was that the authors make very little of the effects of BMI, saying:

 

Models without BMI as a covariate yielded similar results (data not shown). 

 

In other words, whether they ignored BMI or factored it out in their statistical analysis, it didn't make much difference to the mortality results. It was the healthy diet that seemed associated with lower mortality, largely independent of BMI. And for sure there isn't any evidence in this data that being very thin (whether via CR, exercise, or some other intervention), is beneficial. 

 

But I do agree with you that avoiding being obese, or even overweight, is likely to be health-promoting, independent of diet quality - although at advanced age even this may not be the case, as discussed here.

 

--Dean

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