Key Moments
197 - The science of obesity & how to improve nutritional epidemiology | David Allison, Ph.D
Peter Attia MDKey Moments
Obesity science debates data rigor, genetic factors, surgical/pharma. effectiveness vs. public health.
Key Insights
David Allison highlights the complexity and dogmatic thinking in obesity research, emphasizing the need for rigorous evidence and statistical analysis.
The field of obesity research has evolved significantly, from individual behavior focus to recognizing environmental and societal influences, accelerated by NHANES III data and advocacy.
Genetics play a substantial role in obesity, evidenced by twin and adoption studies showing high concordance rates.
Surgical and pharmacological interventions for obesity have advanced, offering significant life-saving benefits, though challenges in access and understanding persist.
Nutritional epidemiology faces significant challenges with measurement error, confounding, and interpretation of findings, necessitating greater honesty and methodological reform.
The 'obesity paradox' suggests a U-shaped relationship between BMI and mortality, with the optimal BMI increasing with age, and interventions require careful causal inference.
THE EVOLUTION OF OBESITY RESEARCH AND METHODOLOGICAL RIGOR
David Allison, a leading figure in obesity research, discusses his background which bridges psychology and statistics, fostering an evidence-based, less dogmatic approach to the field. He contrasts this with the often emotionally charged nature of obesity discussions, highlighting the importance of statistical rigor and objective data analysis over anecdotal evidence or preconceived notions. Allison emphasizes that variables like body fat must be treated with the same scientific scrutiny as any other scientific phenomenon, free from the biases often introduced by personal experience or political agendas that can plague public health discussions.
SHIFTING PARADIGMS: FROM INDIVIDUAL BEHAVIOR TO ENVIRONMENTAL INFLUENCES
Historically, obesity was often viewed through a lens of individual behavior, focusing on caloric intake and expenditure. However, significant shifts occurred in the early 1990s, catalyzed by NHANES III data revealing a dramatic rise in obesity rates, particularly in children. This led to the 'public health policy and environmental perspective,' popularizing concepts like toxic environments and drawing parallels with anti-smoking campaigns. While this broader view attracted more funding and attention, Allison notes a potential dilution of scientific rigor, with opinions and advocacy sometimes overshadowing robust evidence.
GENETICS AND THE BIOLOGICAL UNDERPINNINGS OF OBESITY
The role of genetics in obesity has been recognized for decades, with selective breeding of animals for leanness or fatness providing early evidence. More compelling data comes from twin and adoption studies, particularly those conducted in Nordic countries under Mickey Stunkard's leadership. These studies revealed a remarkably high concordance rate (around 0.9) for BMI in identical twins, whether reared together or apart, indicating a strong genetic predisposition that significantly influences body weight regulation.
ADVANCEMENTS IN TREATMENT: SURGERY AND PHARMACOLOGY
The landscape of obesity treatment has seen substantial progress. Surgical interventions, once considered fringe and dangerous, have become highly effective and safe, notably demonstrated by the Swedish Obese Subjects Study, which showed significant reductions in mortality. Pharmaceutical treatments, initially viewed with suspicion and associated with the fen-phen debacle, are now credible options, with drugs like GLP-1 agonists offering impressive results. While these interventions are life-saving, challenges in access and equitable distribution remain critical issues.
THE NUANCES AND LIMITATIONS OF NUTRITIONAL EPIDEMIOLOGY
Nutritional epidemiology, while valuable, faces significant methodological challenges, including issues with measurement error (especially in food intake data), confounding factors (like smoking and socioeconomic status), and the interpretation of weak associations (e.g., low hazard ratios). Allison uses a mouse study to illustrate how observational data can contradict experimental causal effects, even in highly controlled settings. He advocates for methodological reform, increased intellectual honesty, and a distinction between advocacy and rigorous scientific communication, emphasizing that weak findings should not be overblown into causal claims.
THE 'OBESITY PARADOX' AND THE MOVING NADIR OF MORTALITY
The concept of an 'obesity paradox' refers to the observation that while obesity is generally associated with increased mortality, thinner individuals also face elevated mortality risks (creating a U-shaped or bathtub curve). More intriguingly, the BMI at which mortality is lowest (the nadir) appears to be increasing over time and with age, suggesting that in later life or in aged populations, higher BMI might be protective against certain conditions. This phenomenon complicates simple pronouncements about BMI and mortality and underscores the need for nuanced, age-specific analyses.
BODY COMPOSITION VERSUS BMI AND ETHNIC DIFFERENCES
Although BMI is a widely used tool for population-level research, its limitations at the individual level are significant. It doesn't account for body composition, such as muscle mass versus fat mass, or fat distribution (visceral vs. subcutaneous). Furthermore, BMI thresholds for health risks can vary across ethnicities. For instance, East Asian and Middle Eastern populations may experience increased health risks at lower BMIs, and studies have shown a lack of association between BMI and mortality in some Hispanic American cohorts, highlighting the need for more personalized assessments and culturally sensitive interpretations.
THE CHALLENGE OF WEIGHT MAINTENANCE AND EVOLUTIONARY PERSPECTIVES
Maintaining weight loss is profoundly more difficult than initial weight loss. While evolutionary theories like the 'thrifty gene hypothesis' suggest a biological drive to store energy due to historical food scarcity, Allison questions its universal applicability. Alternative hypotheses, like 'freedom from predation' (John Speakman) or the 'drifty hypothesis,' suggest that reduced selective pressure to maintain thinness, rather than a drive for fatness, may explain modern obesity. The complex interplay of evolutionary pressures, social factors, and modern environments likely contributes to the challenge of sustained weight management.
RETHINKING PUBLIC HEALTH INTERVENTIONS AND THE ROLE OF EDUCATION
Allison expresses skepticism about the effectiveness of many current community-based public health interventions for obesity, suggesting they may be 'looking for keys under the lamppost.' He points to evidence suggesting that general education, particularly for women, and socioeconomic improvements, such as moving to less disadvantaged neighborhoods, may be more impactful in reducing obesity and related diseases. He proposes that societal interventions focusing on reducing disparities and improving education could be more effective than narrowly focused, unproven public health programs.
TRUST, HONESTY, AND THE DISTINCTION BETWEEN SCIENCE AND ADVOCACY
The erosion of public trust in science is a significant concern, exacerbated by factors like the COVID-19 pandemic and issues within scientific communication. Allison emphasizes the critical distinction between speaking as a scientist, which requires unwavering commitment to truth and nuance, and speaking as an advocate, which may involve using persuasive rhetoric. He argues that the scientific community's own obfuscation, exaggeration, and misuse of data have damaged its credibility, particularly in fields like nutrition. Promoting epistemic humility and rigorous, honest scientific discourse is essential to rebuilding trust.
ENHANCING SCIENTIFIC RIGOR AND ADDRESSING NON-NORMATIVE ERRORS
Allison distinguishes between normative errors (unavoidable mistakes due to limitations in knowledge or tools at a given time) and non-normative errors (errors due to flawed methods or willful ignorance). He argues that many current errors in fields like nutrition epidemiology, such as misanalyzing cluster randomized trials or over-relying on food frequency questionnaires for causal inference, are non-normative and unacceptable. He stresses the need for greater rigor, honesty, and a willingness to engage critically with data, methods, and logic, rather than resorting to ad hominem attacks or rhetorical devices.
THE FUTURE OF OBESITY RESEARCH AND INTERVENTION ALLOCATION
Looking forward, Allison suggests a strategic allocation of resources for obesity research and intervention. He proposes dividing funding into four key areas: surgical and pharmaceutical treatments (provision and continued study), general education and socioeconomic disparity reduction, and fundamental basic science research focusing on areas like analytics and microchimerism. This balanced approach acknowledges the progress made in treatment while emphasizing the need for further basic science understanding and broader societal interventions to tackle the complex issue of obesity effectively.
Mentioned in This Episode
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●Studies Cited
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●People Referenced
Common Questions
David Allison's interest in obesity began during undergraduate studies at Vassar College after taking a class on human emotion and motivation, inspired by Stanley Schachter's work. He found obesity research appealing due to its multidisciplinary nature, requiring physiological, psychological, and sociological angles.
Topics
Mentioned in this video
Filmmaker whose work influenced David Allison's initial interest in psychology and interpreting dreams.
Lars Sjostrom's senior mentor, known for his work on fat cell theories and the 'apple versus pear' body shape idea.
The pioneer of the first vaccine, mentioned in the context of John Hunter's emphasis on experimental evidence.
Credited with rediscovering Quetelet's index in the 1960s or 70s and coining the term BMI (Body Mass Index).
Proposed the 'drifty hypothesis' as an alternative evolutionary explanation for obesity, suggesting genes that kept weight down were no longer selected for after humans became predators.
Mentioned as the authority who placed Galileo under house arrest for his writings about Copernicus.
Ole Rømer's mentor, whose predictions about the moon's orbit were contradicted by Rømer's observations, leading to the first convincing evidence for the finite speed of light.
A forceful voice in the obesity field in the mid-90s, who popularized the concept of a 'toxic environment' and shifted focus to public health and prevention.
A key figure in obesity research, known for the cognitive behavioral individual clinical treatment approach, and for conducting the first major high-quality twin and adoption studies.
A researcher who worked with Albert J. Stunkard on twin studies using Nordic data, contributing to the understanding of obesity's genetic component.
Guest on the podcast, a statistician and psychologist known for his work in obesity research, discussing his background and critical views on nutritional epidemiology.
A professor of psychology at Columbia University whose book 'Emotion, Obesity and Crime' and creative experiments hooked David Allison on obesity research, focusing on the external theory of obesity.
A physician and researcher who contributed to the credibility of pharmaceutical treatments for obesity, still active in the field.
Proposed the 'thrifty gene hypothesis' to explain an evolutionary predisposition to obesity, which David Allison finds simplistic.
From Monell Chemical Senses Center, discusses the 'safety of food' as a factor in human eating behavior and obesity from an evolutionary perspective.
Director emeritus of the National Science Foundation and co-chair with David Allison on the National Academy of Sciences strategic council.
Host of the Drive podcast, who interviews David Allison and shares his views on obesity and epidemiology from a clinical perspective.
Led the Swedish Obese Subjects (SOS) study, a controlled trial that provided crucial evidence for bariatric surgery's efficacy in reducing mortality and improving health outcomes.
Referenced in the context of 'the selfish gene' perspective on reproduction, explaining the inefficiency of sexual reproduction from a gene's point of view.
Mentioned in the context of the 'Frisch hypothesis,' suggesting that thinness in women can lead to cessation of menstruation, impacting reproductive fitness.
A colleague highly respected by David Allison, who published a significant meta-analysis in 2005 on BMI and mortality, sparking 'obesity wars,' and highlighting the changing optimal BMI over time.
President of the National Academy of Sciences, who instantiated the new strategic council on trust, integrity, and rigor in science, and appointed David Allison as a co-chair.
Astronomer whose theories Galileo wrote about, leading to his house arrest.
Double Nobel laureate who incorrectly proposed DNA as a triple helix before Watson and Crick, cited as an example of a normative error in science.
Public figure whose statements during the COVID-19 pandemic are used as an example of how public trust can be eroded if nuance is lost in communication, despite potentially well-meaning intentions.
Mentioned by Peter Attia as an early listener of the podcast, being in league with David Allison.
Mentioned as a pioneer in developing formal behavioral therapy tools for obesity, starting in the 1960s.
Mentioned as originating the 'apple versus pear' body shape idea in the 1950s in France, related to fat distribution.
Collaborated on an NIH grant with David Allison and Steve Heymsfield to study 3D photography for body composition.
A famous surgeon cited for telling Edward Jenner, 'Why think? Do the experiment,' emphasizing the importance of experimental evidence.
A Belgian astronomer, epidemiologist, statistician, and mathematician from the 19th century who developed the Quetelet Index, now known as BMI.
Nobel Prize winner who challenged the thrifty gene hypothesis by analyzing historical data on British naval recruits, suggesting humans were not consistently on the brink of starvation.
Author of 'The Knowledge Machine', which beautifully deconstructs scientific processes and talks about the idea of communities engaging in constructive battles based on data.
Former US President, mentioned as being very obese, with historical letters discussing his diet resembling modern-day physician-patient conversations about weight loss.
Co-discoverer of the double helix structure of DNA, correcting Linus Pauling's earlier triple helix proposal.
Celebrity mentioned in contrast to esteemed scientists like Fauci, to highlight how the public struggles to distinguish trustworthy voices in science.
Author of 'Alice in Wonderland' (Alice in the Looking Glass), which provides the 'Red Queen' analogy used to explain co-evolution in biology.
Authored a paper on 'epistemic humility,' advocating for greater honesty in scientific discussions, especially in acknowledging potential errors.
Chair of the National Academy of Sciences panel that concluded there was 'no crisis but no cause for complacency' in science reproducibility.
Astronomer mentioned as conducting an experiment from house arrest to determine the speed of light, which led to a normative error given the limitations of his time.
Credited as the first person to convincingly demonstrate that light does not travel instantaneously, correcting Galileo's earlier conclusion.
Co-discoverer of the double helix structure of DNA, correcting Linus Pauling's earlier triple helix proposal.
A survey that tracks obesity levels in the US, with NHANES III data in the early 1990s highlighting a significant jump in obesity rates.
Kelly Brownell was described as an alumnus or colleague of the University of Pennsylvania.
A prestigious medical journal where key research, such as Stunkard's twin studies and the Swedish Obese Subjects study, was published.
A HUD-funded study that randomly assigned families to move to less poor neighborhoods, resulting in less obesity and diabetes in the intervention group years later.
A controlled trial led by Lars Sjostrom, which demonstrated that bariatric surgery significantly reduced mortality rates and improved obesity-related health outcomes, published in the New England Journal of Medicine.
A famous study, likened to 'Head Start on steroids,' that focused on general education for children, which later found a reduction in obesity rates among women 30 years later.
The first federally funded obesity research center where David Allison worked as a postdoc, providing an environment for rigorous scientific debate.
The institution from which Gary Beauchamp, who has discussed the safety of food in an evolutionary context, hails.
David Allison's undergraduate institution, where he took a class on human emotion and motivation that sparked his interest in obesity research.
The institution where a pathologist noticed the valvulopathy linked to Fen-Phen, leading to its withdrawal.
A government organization that David Allison implies recognizes him as a statistician, also provided a grant for his 3D photography research for body composition.
The US regulatory body that approved phentermine for obesity treatment.
A newspaper mentioned in the context of a reporter asking David Allison about the lack of progress in finding a reliable diet for sustained weight loss.
Funded the Moving to Opportunity study, which investigated the effect of moving families to less poor neighborhoods on health outcomes.
An organization that recognized David Allison as a statistician, aligning with his self-identification later in his career.
David Allison's current academic institution, where he currently works.
An organization where David Allison served on a panel regarding reproducibility in science, and later on a strategic council for trust and integrity.
A government organization that David Allison implies recognizes him as a statistician.
The institution where Stanley Schachter was a professor of psychology.
The foundation under which Davenport published studies on family concordance.
A medical journal where JoAnn Manson and colleagues published a paper on BMI and mortality, and where Catherine Flegal's meta-analysis on obesity and mortality was published.
Its surveys are cited by David Allison to suggest that trust in science as a process is high, while trust in individual elements, like nutrition scientists, compared to others is low.
One of the two drugs in 'Fen-Phen'. It is a catecholaminergic agonist approved by the FDA for obesity treatment, considered relatively safe and modestly effective, and still used today.
A class of drugs mentioned as having life-prolonging effects and being a key intervention for obesity.
One of the two drugs in 'Fen-Phen'. It is a selective serotonergic reuptake inhibitor, originally used for depression, that caused weight loss but was later withdrawn due to causing valvulopathy.
A class of drugs mentioned as having life-prolonging effects for conditions associated with obesity.
Body composition measurement techniques mentioned as better tools than BMI.
A potential future tool for body composition assessment, based on Archimedes' principle, that could provide more accurate and accessible data than BMI at a population level.
A body composition measurement technique mentioned as a better tool than BMI.
A body composition measurement tool, highlighted as superior to BMI for individualized patient assessment due to its ability to measure visceral fat, bone mineral density, and appendicular lean mass.
A concept in evolutionary biology mentioned as one of the complex factors contributing to the mathematical explanation of sexual reproduction's persistence, alongside other theories.
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