by Marion Nestle

Currently browsing posts about: Obesity

Dec 7 2023

No, Virginia, correlation does not necessarily signify causation

On Thursdays I like posting things I want everyone to enjoy.

This one, I stole from Tamar Haspel, who writes about food for the Washington Post.

I follow her on X (the site formerly known as Twitter), where she recently posted:

This could be my all-time favorite BMI correlation!

In China and post-Soviet states, BMI correlates with corruption. The fatter, the crookeder.

The correlation she cites is from an article in the Economist, Are Overweight Politicians Less Trustworthy?

 

 

 

 

 

 

 

 

 

I agree.  This is a fabulous example of how correlation does NOT mean causation—a basic tenet of epidemiology often forgotten.

But here’s my personal favorite example.  I laugh every time I see it.

Image

No, the Dietary Guidelines did not cause the prevalence of obesity to rise.

This is correlation, NOT causation.

For causes, please consider food overproduction, pressures on food companies to sell food when there is so much of it, and the shareholder value movement, which demands not only profits, but  continual growth in profits.  All of these forced food companies to find new ways to get everyone to eat more food (by creating an “eat more” food environment.  I discuss all this in Food Politics and my other books).

Correlation is lots of fun but causation requires much deeper analyses.

Sorry about that.

Thanks Tamar.

Nov 2 2023

Toward a national campaign to prevent weight-related chronic disease

Jerry Mande, a co-founder of Nourish Science wrote me to urge support for a national action plan to reduce obesity—and the chronic diseases for which it raises risks. (Note: he also has an op-ed in The Hill on NIH research and leadership needs).

Here is what we should do. It’s time for a new federal nutrition goal. For decades it’s been some variation of “access to healthier options and nutrition information.” Jim Jones [the new head of food and nutrition at FDA] used that last week in his vision for the new human foods program. It’s in USDA FNS’s mission too. The WaPo reporting on life expectancy, fatty liver disease, & Lunchables in school meals reveals that goal has failed and needs to be replaced.

The goal should be updated to: ensuring that every child reaches age 18 at a healthy weight and in good metabolic health. Cory Booker proposed making it the U.S. goal in his attached letter to Susan Rice on the WHC [White House Conference]. It’s part of the Nourish Science vision.

It’s doable.  USDA has the necessary power, reach, and resources. Over half of infants are on WIC, 1/3 of children in CACFP [Child and Adult Care Feeding Program], virtually all in school meals, and almost ½ of SNAP recipients are under 18. If we leveraged those programs to achieve the new goal and with FDA’s & CDC’s help, we could make substantial progress. For example, USDA was able to raise school meal HEI [Healthy Eating Index] scores from failing U.S. average of 58 to an acceptable 82 in just three years.

We have a successful blueprint in FDA regulation of tobacco. When we began our FDA investigation in 1993 1/3 of adults and ¼ of kids smoked cigarettes. Today we have a $700M FDA tobacco center and 11% of adults and only 2% of high school students smoke cigarettes.

We should set the new goal in the upcoming Farm Bill. We should change USDA’s name to the U.S. Department of Food and Agriculture and state the new goal.

The only needed ingredient to make this happen is an effective federal nutrition champion. That’s how tobacco happened.

I’m optimistic. We can do this.

I like the vision.  I’m glad he’s optimistic.  Plenty of work to do to get this on the agenda.

Some background

Sep 29 2023

Weekend reading: rising prevalence of obesity in developing countries

The International Fund for Agricultural Development (IFAD), as part of its IFAD Research Series, released a report, Overweight and obesity in LMICs in rural development and food systems, along with a literature review.

The report finds obesity rates across developing countries to be approaching levels found in high-income countries.

The study attributes the rise to:

  • Food Prices: The price gap between healthy foods (expensive) and unhealthy foods (inexpensive) is greater in developing countries than in rich developed countries.
  • Diet: Sugar-sweetened beverage consumption is on the rise in developing countries and the global sales of highly processed foods rose from 67.7kg per capita in 2005 to 76.9kg in 2017.
  • Culture: In some developing countries, childhood fatness is associated with health and wealth and consumption of unhealthy foods carries prestige.
  • Gender: Women are more likely to be overweight or obese than men in nearly all developing countries.

One strength of this study is its consideration of the need for interventions across the entire food system:

The study results show that food system-related interventions are not overweight or obesity specific. Instead, they tap into the wider field of making diets more healthy and nutritious, and emerge as necessary strategies to set the scene for creating non-obesogenic food supply chains. The identified intervention strategies cut across different food system domains: there were production strategies for improved dietary diversity, strategies for processing (which involved food package labelling or price mechanisms), strategies for changing the food environment and strategies to address consumer behaviour.

Jun 29 2023

American Medical Association resolves to limit BMI as standard medical measure

I have been asked to comment on the American Medical Association’s resolution to stop using the BMI as the sole criterion for diagnosing obesity [To find this resolution, click on CCSPH Report(s) #07: Support Removal of BMI as a Standard Measure in Medicine and Recognizing Culturally-Diverse and Varied Presentations of Eating Disorders].

The BMI—Body Mass Index—defined as weight in kilograms divided by height in meters squared—is a quick way to categorize the relationship of weight to height and does a better job of identifying people with excessive body fat than most other simple and inexpensive measures.

Unfortunately, not everyone demonstrates a close correlation of BMI to body fat and those who don’t may well find themselves discriminated against in the health care system.

The BMI is also an imperfect measure of health risk:

The current BMI classification system is also misleading regarding the effects of body fat mass on mortality rates. Numerous comorbidities, lifestyle issues, gender, ethnicities, medically significant familial-determined mortality effectors, duration of time one spends in certain BMI categories, and the expected accumulation of fat with aging are likely to significantly affect interpretation of BMI data, particularly in regard to morbidity and mortality rates…[This report] outlines the harms and benefits to using BMI and points out that BMI is inaccurate in measuring body fat in multiple groups because it does not account for the heterogeneity across race/ethnic groups, sexes, and age-span.

The resolution recommends:

(1) greater emphasis in physician educational programs on the risk differences among ethnic and age within and between demographic groups at varying
levels of adiposity, BMI, body composition, and waist circumference and the importance  of monitoring these waist circumference in all individuals with BMIs below 35 kg/m2;

(2) additional research on the efficacy of screening for overweight and obesity, using different indicators, in improving various clinical outcomes across populations, including morbidity, mortality, mental health, and prevention of further weight gain; and

(3) more research on the efficacy of screening and interventions by physicians to promote healthy lifestyle behaviors, including healthy diets and regular physical activity, in all of their patients to improve health and minimize disease risks.

My translation: Keep using the BMI as an indicator, but also pay attention to body composition and waist circumference as better measures of body fat.

The AMA is not minimizing the importance of excess body fat as a disease risk factor.  It is saying that only using the BMI to evaluate the risk itself risks stigmatizing patients, especially those of non-majority race, ethnicity, and gender conformation.

This resolution ought to further sensitize physicians to such issues.  If it does, it could not come a better time.

Resources

I am putting the Keys’ paper into this discussion to demonstrate that Keys was quite well aware of the strengths and weaknesses of the BMI, which was intended mainly to identify groups and populations at risk of undernutrition.

Guided by the criteria of correlation with height (lowest is best) and to measures of body fatness (highest is best), the ponderal index is the poorest of the relative weight indices studied.  The ratio of weight to height squared, here termed the body mass index, is slightly better in these respects than the simple ratio of weight to height. The body mass index seems preferable over other indices of relative weight on these grounds as well as on the simplicity of the calculation and, in contrast to percentage of average weight, the applicability to all populations at all times.

Mar 10 2023

Weekend reading: stopping the rising prevalence of overweight and obesity

The World Obesity Atlas 2023, published by World Obesity Federation, predicts that unless preventive interventions succeed, by 2035:

  • The global economic impact of overweight and obesity will reach $4.32 trillion annually and constitute nearly 3% of global GDP.
  • The majority—51% or more than 4 billion people—will be living with overweight or obesity.
  • One in four people—nearly 2 billion—will have obesity.
  • The economic impact of overweight and obesity is estimated to be over $370 billion a year in low and lower-middle income countries alone.
  • Childhood obesity could more than double.

Here’s the prediction for the U.S.

In the report, the World Obesity Federation:

  • Notes that member states of WHO committed to halt the increase in obesity rates at 2010 levels by 2025. No country is on track to meet these targets.
  • Calls on governments to develop national action plans.
  • Calls on governments to improve health care.
  • Calls for building on the ROOTS framework for tackling obesity: Recognising the root causes, monitoring Obesity data, investing in Obesity prevention, ensuring access to Treatments, and adopting a Systems-based approach.

The documents:

Comment

This is a global problem requiring global solutions., and actions by every government, including ours.   We need a national obesity prevention plan focused on strategies like to work (reduction of food insecurity, improved health care, better education, restrictions on marketing junk food, etc).

Otherwise,  we are all headed to Wall-E, which will turn out to be prescient, rather than dystopian.

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Aug 9 2022

My latest publication: Preventing Obesity

JAMA Internal Medicine has just published an editorial I wrote: Preventing Obesity—It Is Time for Multiple Policy Strategies

As it explains, it is a commentary on a research article by Joshua Petimar, et al, Assessment of Calories Purchased After Calorie Labeling of Prepared Foods in a Large Supermarket Chain  

Both papers are behind paywalls, but here are the key points of the supermarket article:

Question  Was calorie labeling of prepared foods in supermarkets associated with changes in calories purchased from prepared foods and potential packaged substitutes?

Findings  In this longitudinal study of 173 supermarkets followed from 2015 to 2017, calories purchased from prepared bakery items declined by 5.1% after labeling, and calories purchased from prepared deli items declined by 11.0% after labeling, adjusted for prelabeling trends and changes in control foods; no changes were observed among prepared entrées and sides. Calories purchased from similar packaged items did not increase after labeling.

Meaning  Calorie labeling of prepared supermarket foods was associated with overall small declines in calorie content of prepared foods without substitution to similar packaged foods.

I was really interested in this study because the “large supermarket chain” that supplied reams of data was so obviously Hannaford, which has long been ahead of the curve in trying to encourage customers to make healthier food choices.

In 2005, Hannaford initiated a Guiding Stars program that ranked–and still ranks–products by giving them zero to three stars depending on what they contain.

I wrote about the first-year evaluation of this program way back in 2006.  It did help customers to make better choices.

Now, all these years later, the FDA is contemplating doing some kind of front-of-package label.  As I said, Hannaford is way ahead.

But the point of my editorial is that single interventions rarely do better than what this study found.

I argue here for trying multiple strategies at once:

My interpretation of the current status of obesity prevention research is that any single policy intervention is unlikely to show anything but small improvements.

Pessimists will say such interventions are futile and should no longer be attempted.

Optimist that I am, I disagree.  We cannot expect single interventions to prevent population-basedweight gain ontheirown,but they might help some people—and might help even more people if combined simultaneously with other interventions.

….Widespread policy efforts to reduce intake of ultraprocessed foods through a combination of taxes, warning labels, marketing and portion-size restrictions, dietary guidelines, and media education campaigns, along with policies for subsidizing healthier foods and promoting greater physical activity, should be tried; they may produce meaningful effects.

Politically difficult? Of course. Politically impossible? I do not think so.

Unless we keep trying to intervene—and continue to examine the results of our attempts—we will be settling for the normalization of overweight and the personal and societal costs of its health consequences.

Here’s Ted Kyle’s commentary on my commentary on ConscienHealth.

Apr 21 2022

The FDA needs to take on obesity (and so do other government health agencies)

In response to my post last week about problems at the FDA, I received an emailed note from Jerry Mande, whom I met years ago when he was at USDA, and is now a visiting fellow at the Harvard School of Public Health.

Terrific piece today, but you should have called for the need for FDA to focus much more on the chronic disease risks of food. It’s catastrophic that they have taken only one truly regulatory action (banning trans fat) to improve diet and health…Commissioner Califf needs to put the F back in FDA only 7% of CFSAN’s budget is used for improving diet quality and nutrition, which accounts for 99%+ of food related poor health…The bottom line, as you know better than anyone, is there are more deaths every day due to poor quality diets than in a year due to acute illnesses…I urge you to consider that when you write more on this topic. You could start by featuring our op-ed in your blog. Thx!

The op-ed is indeed worth a read.

But, in fact, this topic has been on my mind since Politico’s Helena Bottemiller Evich wrote Diet-related diseases pose a major risk for Covid-19.  But the U.S. overlooks them, back in October.

Her article, which focused on the lack of government attention to the risks posed by obesity for chronic disease and COVID-19, inspired me to write an editorial for the American Journal of Public Health.  I’m told it’s going online tonight (if it does, I will post it tomorrow).

Jul 12 2021

Conflicted interests? Drugs vs supplements for obesity

Lots of people take supplements in the hope that they will help with body weight.  This is a big market.  Drug companies want in on it.  Most drugs don’t work, or have deal-breaking side effects.  In June,  The FDA approved Novo Nordisk’s Semaglutide for obesity management.

I subscribe to the Obesity and Energetics newsletter, which sends out weekly lists of research, articles, and commentary on those topics—a great way to stay up on current literature.

On July 2, it featured:

This referred to: Perspective: Dietary supplements and alternative therapies for obesity: A Perspective from The Obesity Society’s Clinical Committee.  Srividya Kidambi, John A. Batsis, William T. Donahoo, Ania M. Jastreboff, Scott Kahan, Katherine H. Saunders, Steven B. Heymsfield.  Obesity 23 June 2021.

Our recommendation to clinicians is to consider the lack of evidence for non-FDA-approved dietary supplements and therapies and guide their patients toward tested weight management approaches…we call on regulatory authorities to critically examine the dietary supplement industry, including their role in promoting misleading claims and marketing products that have the potential to harm patients.

I am with the Obesity Society on this one, but what caught my interest was that several of the authors report financial tied to drug companies with interests in pharmacologic approaches to obesity treatment.

Conflicts of interest: SK serves as Medical Editor for TOPS Magazine (TOPS Inc. nonprofit weight loss club) and as Director for the TOPS Center for Metabolic Research at the Medical College of Wisconsin supported by TOPS Inc. JAB’s research reported in this publication was supported in part by the National Institute on Aging of the National Institutes of Health (NIH) under Award Number K23AG051681. JAB reports equity in SynchroHealth LLC. AMJ’s research is supported by the NIH/NIDDK, the American Diabetes Association, Novo Nordisk, and Eli Lilly; she serves as a consultant for Novo Nordisk, Eli Lilly, and Boehringer Ingelheim. SKa has served as a consultant for Novo Nordisk, Vivus, Gelesis, and Pfizer. KHS reports an ownership interest in Intellihealth. SBH reports his position on the Medical Advisory Board of Medifast Corp.

The newsletter also featured the article referred to in the Perspective.

When I clicked on this link, it took me to the page where I could download the pdf.  I got the paper at this site.   But before I could read it, I had to see an ad for Novo Nordisk’s drug, Semaglutide.  Then I scrolled down to get the study:  A Systematic Review of Dietary Supplements and Alternative Therapies for Weight Loss.  John A. Batsis, John W. Apolzan, Pamela J. Bagley, Heather B. Blunt, Vidita Divan, Sonia Gill, Angela Golden, Shalini Gundumraj, Steven B. Heymsfield, Scott Kahan, Katherine Kopatsis … Obesity (2021) 29, 1102-1113

Study conclusion: “There is weak evidence for the efficacy of dietary supplements and alternative therapies.”

Authors’ disclosure: JAB reports equity in SynchroHealth LLC. AG reports consulting with Novo Nordisk and Unjury. SH reports personal fees from Medifast. SKa reports personal fees from Novo Nordisk, Pfizer, Vivus, and Gelesis. DR reports consulting and speaking fees for Novo Nordisk and Astra Zeneca. KHS has a relationship with Intellihealth Inc. SK is the medical director for TOPS Center for Metabolic Health at the Medical College of Wisconsin, which is supported by TOPS Inc. SBH reports his position on the Medical Advisory Board of Medifast Corp.

I much prefer dietary approaches to weight management and policy strategies to make healthy diets the easy choice.

I am almost never in favor of supplements.  The evidence that they do much beyond placebo effects is usually pretty weak.

The ad gives the side effects for Semiglutide; it has to.

My point: all of this seems to be about marketing Semiglutide.