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Wednesday, October 1, 2014

Diet research, stuck in the stone age

You cannot get a good answer to a lousy question.

The current diet study making headlines purportedly asked, and answered this question: Which is better for weight loss and improving cardiac risk, a low-fat or a low-carb diet? For starters, that is a truly lousy question, resurrected from something like the Stone Age. I doubt even the Paleo clan find the question attractive, since they like prehistoric food, not prehistoric research questions about food.

Why prehistoric? Because it is long known and well established that dietary fats run the gamut from good to bad to ugly. No good diet should willfully exclude the monounsaturated fats and omega-3s in nuts and seeds and avocados. I’m pretty sure everybody not stuck under a boulder knows that.

There is ongoing debate today about specific effects of specific fats, but the wholesale cutting of dietary fat intake was pretty much yesterday’s news yesterday. The relevant concept today would be plant-based eating, which at the extreme of veganism, tends to be low in fat, but as an effect rather than an objective. This was not a study of a vegan diet.

The concept of low-carb is also terribly outdated, and was silly when it was first spawned. Everything from lentils to lollipops is carbohydrate. Why on earth would anyone want to treat such a vast expanse of the food supply as if it were just one thing? Sillier still, all plant food is a carbohydrate source. A truly “low-carb” diet is, of necessity, low in all plant foods, including vegetables, fruits, nuts, seeds, beans, and lentils along with whole grains. This is directly at odds with everything we know about diet and health across the lifespan.

So the research question in this case was, in a word, dumb. But now let me tell you what I really think.

The study didn’t even really ask this question. If you only read the headlines, you will believe it did, and frankly, most people will only read the headlines. I read the study, and before you start arguing with me, I invite you to do the same.

It was published in the Annals of Internal Medicine, and frankly redounds much to the shame of this generally prestigious journal. Allegedly, the researchers compared a low-fat to a low-carb diet. But in fact, they compared a diet that allowed up to 30 percent of calories from fat to a diet that allowed up to 40 grams of daily carbohydrate.

The baseline diets were, reportedly, roughly 2,000 calories per day on average among the nearly 140 obese (i.e., BMI >30) study participants. (This is a bit suspect, since calorie intake would be predicted to be higher in obese adults.) That means the allegedly low-fat diet assignment allowed up to 600 calories per day from fat, while the low-carb assignment allowed only about one-quarter that much carbohydrate, 160 calories. The baseline fat intake of the participants in the low-fat assignment was just over 35 percent of calories, so this was, essentially, a diet intervention that didn’t intervene much with their diets.

In contrast, baseline carbohydrate intake was 240 grams per day, so while fat intake was “trimmed” 5 percent, carbohydrate intake in that assignment was slashed 75 percent. This might have been billed “a study to compare a really big change from baseline diet to a really small change from baseline diet.” I suppose we can all guess why it wasn’t called that.

That would be bad and biased enough if the researchers had made any attempt to compare comparably good, or comparably bad versions of the two diets; but they did not. The “low-fat” diet was, for starters, not much lower in fat than the typical American diet, which as we all know, is basically crap. Shockingly, the fiber intake was virtually identical, at about 15 to 16 grams per day, in both groups throughout the study. You cannot possibly eat any variant on the theme of “good” low-fat, mostly plant-based eating and fix the fiber intake at that pitiful level. The only way to do that is to combine modestly low fat with preferentially crummy foods made mostly from refined starches and added sugars. The study did not provide this level of detail about the diets, but it’s clear that the low fat diet was (A) not low fat; and (B) rather crummy. So another title option was: “a comparison of the best low-carb diet to the worst low-fat diet we could come up with.” Again, I think it’s clear why they didn’t go with that one.

And finally, the low-carb diet, since it was actually low-carb, obviously was much more restrictive than the low-fat diet, which wasn’t actually low-fat. That had the predictable result: those on the low-carb assignment took in many fewer calories (this information in summarized in Table 2 in the article). Over the first several months of the study, when everyone was probably on their best behavior, the low-carb group took in about 200 fewer calories per day. All the way out at the 12-month mark, when folks were falling off the wagon, the low-carb assignees were still taking in nearly 100 fewer calories per day.

And so, the results were a foregone conclusion. Over the span of a year, obese people who ate less, lost more weight. And those who lost more weight had more improvement in their cardiac risk measures, which were mostly a mess in the first place due to obesity. Ta-da!

Folks, this is not a defense of low-fat diets. I am not an advocate of low-fat diets. I think the concept is obsolete. I am an advocate, based on the evidence, of wholesome foods in sensible combinations. That dietary pattern can be low or high in fat, relatively lower or higher in carbohydrate. The theme is pretty universal, but the variant on the theme that best suits you and your family is really up to you, and frankly, that’s the beauty of it. All of us can hope to love the food that loves us back.

But I am an advocate of research that is fair, unbiased, and relevant in the real world. As the head of a clinical research lab, and the author of textbooks on research methods, I am an advocate of sound answers to sensible questions. This is a defense of sense, and good science. Neither of which was on display in this study. As best I can tell, neither was fairness, nor even honesty. The researchers themselves called their interventions “low-fat” and “low-carbohydrate,” and must have known from the start they were cooking those definitions over very different fires.

As a medical journalist, I am a proponent of reading past headlines. Headlines want to titillate you, not educate you. If you are comfortable, they are designed to afflict you. If you are afflicted, they are designed to comfort you. The truth, the whole truth, and nothing but the truth are for the most part, entirely expendable. Proceed accordingly.

If this had actually been a study comparing comparably good (or comparably bad), genuinely low-fat and low-carb diets, it would still be research stuck in the Stone Age. Such questions have been asked and answered before, and we can do much better. Had it been such a study, it would still belong on the walls of a cave, rather than the pages of a generally high-quality, peer-reviewed journal. But it might at least have been antique honesty.

But it was not such a study at all. It is both prehistoric and propaganda. It was a comparison of a quite restricted, lower-calorie, low-fiber diet; to a less restricted, higher calorie, equally low-fiber diet. The first worked better for weight loss. Ignored in the mix? Was the diet sustainable when the intervention ended? Could families join in? Would the diet reliably improve health and prevent disease across a lifespan?

Not relevant, because this was a study designed to generate a predictably useless, misleading, and potentially harmful answer to an egregiously silly and perhaps even willfully disingenuous question. If science were generally this bad, we would never have exited the Stone Age.

David L. Katz, MD, FACP, MPH, FACPM, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care. He is a board certified specialist in both Internal Medicine, and Preventive Medicine/Public Health, and Associate Professor (adjunct) in Public Health Practice at the Yale University School of Medicine. He is the Director and founder (1998) of Yale University's Prevention Research Center; Director and founder of the Integrative Medicine Center at Griffin Hospital (2000) in Derby, Conn.; founder and president of the non-profit Turn the Tide Foundation; and formerly the Director of Medical Studies in Public Health at the Yale School of Medicine for eight years. This post originally appeared on his blog at The Huffington Post.

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Blog log

Members of the American College of Physicians contribute posts from their own sites to ACP Internistand ACP Hospitalist. Contributors include:

Albert Fuchs, MD
Albert Fuchs, MD, FACP, graduated from the University of California, Los Angeles School of Medicine, where he also did his internal medicine training. Certified by the American Board of Internal Medicine, Dr. Fuchs spent three years as a full-time faculty member at UCLA School of Medicine before opening his private practice in Beverly Hills in 2000.

And Thus, It Begins
Amanda Xi, ACP Medical Student Member, is a first-year medical student at the OUWB School of Medicine, charter class of 2015, in Rochester, Mich., from which she which chronicles her journey through medical training from day 1 of medical school.

Auscultation
Ira S. Nash, MD, FACP, is the senior vice president and executive director of the North Shore-LIJ Medical Group, and a professor of Cardiology and Population Health at Hofstra North Shore-LIJ School of Medicine. He is Board Certified in Internal Medicine and Cardiovascular Diseases and was in the private practice of cardiology before joining the full-time faculty of Massachusetts General Hospital.

Zackary Berger
Zackary Berger, MD, ACP Member, is a primary care doctor and general internist in the Division of General Internal Medicine at Johns Hopkins. His research interests include doctor-patient communication, bioethics, and systematic reviews.

Controversies in Hospital Infection Prevention
Run by three ACP Fellows, this blog ponders vexing issues in infection prevention and control, inside and outside the hospital. Daniel J Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. Michael B. Edmond, MD, FACP, is a hospital epidemiologist in Iowa City, IA, with a focus on understanding why infections occur in the hospital and ways to prevent these infections, and sees patients in the inpatient and outpatient settings. Eli N. Perencevich, MD, ACP Member, is an infectious disease physician and epidemiologist in Iowa City, Iowa, who studies methods to halt the spread of resistant bacteria in our hospitals (including novel ways to get everyone to wash their hands).

db's Medical Rants
Robert M. Centor, MD, FACP, contributes short essays contemplating medicine and the health care system.

Suneel Dhand, MD, ACP Member
Suneel Dhand, MD, ACP Member, is a practicing physician in Massachusetts. He has published numerous articles in clinical medicine, covering a wide range of specialty areas including; pulmonology, cardiology, endocrinology, hematology, and infectious disease. He has also authored chapters in the prestigious "5-Minute Clinical Consult" medical textbook. His other clinical interests include quality improvement, hospital safety, hospital utilization, and the use of technology in health care.

DrDialogue
Juliet K. Mavromatis, MD, FACP, provides a conversation about health topics for patients and health professionals.

Dr. Mintz' Blog
Matthew Mintz, MD, FACP, has practiced internal medicine for more than a decade and is an Associate Professor of Medicine at an academic medical center on the East Coast. His time is split between teaching medical students and residents, and caring for patients.

Everything Health
Toni Brayer, MD, FACP, blogs about the rapid changes in science, medicine, health and healing in the 21st century.

FutureDocs
Vineet Arora, MD, FACP, is Associate Program Director for the Internal Medicine Residency and Assistant Dean of Scholarship & Discovery at the Pritzker School of Medicine for the University of Chicago. Her education and research focus is on resident duty hours, patient handoffs, medical professionalism, and quality of hospital care. She is also an academic hospitalist.

Glass Hospital
John H. Schumann, MD, FACP, provides transparency on the workings of medical practice and the complexities of hospital care, illuminates the emotional and cognitive aspects of caregiving and decision-making from the perspective of an active primary care physician, and offers behind-the-scenes portraits of hospital sanctums and the people who inhabit them.

Gut Check
Ryan Madanick, MD, ACP Member, is a gastroenterologist at the University of North Carolina School of Medicine, and the Program Director for the GI & Hepatology Fellowship Program. He specializes in diseases of the esophagus, with a strong interest in the diagnosis and treatment of patients who have difficult-to-manage esophageal problems such as refractory GERD, heartburn, and chest pain.

I'm dok
Mike Aref, MD, PhD, FACP, is an academic hospitalist with an interest in basic and clinical science and education, with interests in noninvasive monitoring and diagnostic testing using novel bedside imaging modalities, diagnostic reasoning, medical informatics, new medical education modalities, pre-code/code management, palliative care, patient-physician communication, quality improvement, and quantitative biomedical imaging.

Informatics Professor
William Hersh, MD, FACP, Professor and Chair, Department of Medical Informatics & Clinical Epidemiology, Oregon Health & Science University, posts his thoughts on various topics related to biomedical and health informatics.

David Katz, MD
David L. Katz, MD, MPH, FACP, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care.

Just Oncology
Richard Just, MD, ACP Member, has 36 years in clinical practice of hematology and medical oncology. His blog is a joint publication with Gregg Masters, MPH.

KevinMD
Kevin Pho, MD, ACP Member, offers one of the Web's definitive sites for influential health commentary.

MD Whistleblower
Michael Kirsch, MD, FACP, addresses the joys and challenges of medical practice, including controversies in the doctor-patient relationship, medical ethics and measuring medical quality. When he's not writing, he's performing colonoscopies.

Medical Lessons
Elaine Schattner, MD, FACP, shares her ideas on education, ethics in medicine, health care news and culture. Her views on medicine are informed by her past experiences in caring for patients, as a researcher in cancer immunology, and as a patient who's had breast cancer.

Mired in MedEd
Alexander M. Djuricich, MD, FACP, is the Associate Dean for Continuing Medical Education (CME), and a Program Director in Medicine-Pediatrics at the Indiana University School of Medicine in Indianapolis, where he blogs about medical education.

More Musings
Rob Lamberts, MD, ACP Member, a med-peds and general practice internist, returns with "volume 2" of his personal musings about medicine, life, armadillos and Sasquatch at More Musings (of a Distractible Kind).

Prescriptions
David M. Sack, MD, FACP, practices general gastroenterology at a small community hospital in Connecticut. His blog is a series of musings on medicine, medical care, the health care system and medical ethics, in no particular order.

Reflections of a Grady Doctor
Kimberly Manning, MD, FACP, reflects on the personal side of being a doctor in a community hospital in Atlanta.

The Blog of Paul Sufka
Paul Sufka, MD, ACP Member, is a board certified rheumatologist in St. Paul, Minn. He was a chief resident in internal medicine with the University of Minnesota and then completed his fellowship training in rheumatology in June 2011 at the University of Minnesota Department of Rheumatology. His interests include the use of technology in medicine.

Technology in (Medical) Education
Neil Mehta, MBBS, MS, FACP, is interested in use of technology in education, social media and networking, practice management and evidence-based medicine tools, personal information and knowledge management.

Peter A. Lipson, MD
Peter A. Lipson, MD, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. The blog, which has been around in various forms since 2007, offers musings on the intersection of science, medicine, and culture.

Why is American Health Care So Expensive?
Janice Boughton, MD, FACP, practiced internal medicine for 20 years before adopting a career in hospital and primary care medicine as a locum tenens physician. She lives in Idaho when not traveling.

World's Best Site
Daniel Ginsberg, MD, FACP, is an internal medicine physician who has avidly applied computers to medicine since 1986, when he first wrote medically oriented computer programs. He is in practice in Tacoma, Washington.

Other blogs of note:

American Journal of Medicine
Also known as the Green Journal, the American Journal of Medicine publishes original clinical articles of interest to physicians in internal medicine and its subspecialities, both in academia and community-based practice.

Clinical Correlations
A collaborative medical blog started by Neil Shapiro, MD, ACP Member, associate program director at New York University Medical Center's internal medicine residency program. Faculty, residents and students contribute case studies, mystery quizzes, news, commentary and more.

Interact MD
Michael Benjamin, MD, ACP member, doesn't accept industry money so he can create an independent, clinician-reviewed space on the Internet for physicians to report and comment on the medical news of the day.

PLoS Blog
The Public Library of Science's open access materials include a blog.

White Coat Rants
One of the most popular anonymous blogs written by an emergency room physician.

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