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Anyone who is active on social media has come to expect a certain degree of tribalism around the issues of the day: guns, climate change, abortion, politics, and the like. We’ve been surprised to see it creep into the online conversation about nutrition science, especially the discussion about low-carbohydrate, high-fat diets. Even more surprising to us is that such advocacy sometimes comes from health professionals, scientists, and journalists, from whom we would normally expect a certain degree of objectivity.

These diets aren’t new. William Banting described in 1863 how a low-carbohydrate diet helped him lose weight, and since the 1970s the low-carb Atkins and South Beach diet books have sold millions of copies. Emerging data show that low-carb, high-fat diets can lead to reduced weight and better control of blood sugar, insulin, triglycerides, and possibly blood pressure. But they may increase cholesterol in the bloodstream, which has been associated with an increased risk of heart disease. That doesn’t necessarily mean low-carb, high-fat diets increase the risk of heart attack in everyone — or even in those with high cholesterol — because of the many potential benefits associated with these diets.

It’s a classic issue of balancing benefits and risks, one complicated because it isn’t clear if, how much, or in whom an increase in cholesterol even matters. That’s why there is general consensus that rigorous clinical trials are needed to answer this critical question.


The role of advocates who work on behalf of a cause or group can be essential to the success of these movements. But advocates also inflame the bitterness inherent in these battles. Given the current discourse in nutrition science, it can be hard to disentangle science from advocacy.

The idea that a dietary intervention might affect heart attack risk isn’t complicated or controversial. According to the cholesterol hypothesis, too much low-density lipoprotein (the so-called bad cholesterol) in the blood leads to its deposition in artery walls; the resulting plaque can block arteries and lead to heart attack or stroke. This theory has been bolstered by decades of evidence ranging from epidemiological associations to genetic studies and interventional drug trials. There may be no better studied pathway in modern medicine.


We believe in low-carb, high fat nutrition. One of us (E.J.W.) advises a company that uses this approach to treat individuals with type 2 diabetes and also recently co-founded a company using this approach for weight loss. The other (N.G.) uses low-carb, high-fat nutrition with her own patients and is the principal investigator of multiple studies of low-carb, high-fat nutrition in type 1 and 2 diabetes. We see this approach to nutrition as an exciting tool in the management of weight and cardiometabolic disease.

Yet we are disturbed by the discourse surrounding these diets, which often feels less like science and more like cheerleading. To be sure, nutritional tribalism is not limited to discussions about the relative merits or demerits of low-carb, high-fat diets. The evidence that nutrition has become a team sport is found in Twitter handles of individuals rooting for their favorite nutritional movement, such as small plant emojis in the Twitter handles of vegan advocates or a Ó in those promoting carnivore-type diets.

To bolster their cause for low-carb, high-fats diets, these advocates, including some scientists and doctors, claim that the cholesterol hypothesis is a conspiracy led by pharmaceutical companies in an effort to sell more drugs. Others have suggested that cholesterol may actually protect against cardiovascular disease. This goes on and on.

The effort to discredit the role of cholesterol in cardiovascular disease is striking because the evidence linking elevated cholesterol to heart attack risk is so strong. This makes us wonder why advocates might take this approach.

It’s possible that acknowledging an unknown risk might undermine or discredit the benefits of low-carb, high-fat nutrition. But that kind of thinking ignores a central tenet of medicine: Everything we do in medicine — from appendectomies to cancer chemotherapies to diet therapy — has benefits and risks. If a chemotherapy has a 10% chance of a side effect, that doesn’t make it any less likely to cure the cancer. So why would we treat the science of nutrition any differently? Perhaps because science has morphed into advocacy. Successful advocacy demands a clear narrative, yet science and biology are inherently gray.

The conversation about low-carb, high-fat nutrition is being painted as binary without room for nuance, when nuance is exactly what is required. The choice for individuals following low-carb, high-fat diets isn’t should they quit the diet or ignore the science. There are other choices, such as seeking testing to better define cardiovascular risk or taking a statin or other medication if needed. It’s also possible to change the types of high-fat foods in the diet, emphasizing those with unsaturated fats such as olive oil, salmon, avocado, or nuts while eating fewer foods with saturated fats such as butter, cream, and bacon. These approaches aren’t anti-low-carb, high-fat nutrition.

Nutrition science may be especially ripe for advocacy because of the linked epidemics of obesity and type 2 diabetes that so clearly stem from our changing lifestyles. And everyone has a stake in nutrition. But that is all the more reason we should be clear-eyed about what we know, even if what we know is “we don’t know.” We all have to eat, and make our choices based on imperfect evidence.

Of course, if a high-quality, large-scale, randomized control trial showed conclusively that the risks of the low-carb, high-fat approach outweighed the benefit, as health professionals and scientists we would accept that. In the other direction, if low-carb, high-fat diets were shown to protect against cardiovascular disease — regardless of their effect on LDL cholesterol — then that should be accepted and integrated into clinical practice.

We believe that the intrusion of advocacy into science has led to reductionism and the creation of false dichotomies. We believe that scientists, health care professionals, and journalists must avoid intentionally confusing or alarming the public in an attempt to discredit legitimate science, ultimately in the name of advocating for an agenda.

In addition to being dangerous, such ostensible advocacy appears to be an intentional attempt to degrade the public’s trust in science. One need look no further than the tragedy of the false story linking vaccines to autism as an example of what can and will result.

Nicola Guess, Ph.D., is a registered dietitian, associate professor of nutrition at the University of Westminster in London, head of nutrition at the Dasman Diabetes Institute in Kuwait, and a director of CityDietitians, a private clinical and consultancy company based on London. Ethan J. Weiss, M.D., is a preventive cardiologist and associate professor of medicine at the University of California, San Francisco.

Guess reports having received research or fellowship funding from Diabetes UK, the Medical Research Council, Diabetes Research and Wellness Foundation, American Overseas Dietetic Association, Chronic Disease Research Foundation, Winston Churchill Memorial Trust, and Oviva, and speaking or consultancy fees from Sanofi, Boehringer Ingelheim, and Fixing Dad (a low-carb app). Weiss reports having received research funding from the National Institutes of Health, Pfizer, and Lilly. He is an advisor to Virta Health and a co-founder and advisor to Keyto, Inc.

  • Linking low-carbohydrate/high-fat “advocates” to zealots is ridiculous. All of the LCHF clinicians that I know (and I know literally hundreds) base their “advocacy” on rigorous science. Unlike the founders and promoters of the “Dietary Guidelines for Americans”, whose flawed “findings” and advice have helped significantly to create the obesity and diabetes epidemics.
    The LCHF professionals with whom for yearsI have been privileged to work never promote any protocol without thorough scientific back-up.
    Advocating on the basis of a firm foundation in science is not zealotry … it is good practice.

  • “One need look no further than the tragedy of the false story linking vaccines to autism as an example”.. then why does the US Government operate a department called VICP, Vaccine Injury Compensation Program, where they have handed out over $4billion to victims.
    Also while I’m here I may as well remind people of the greatest hoax of all, HIV causes Aids. Read this link from Noble winner Kary Mullis and if you remain convinced it does then you need a good thrashing.

    Last but not least my kindle book ‘How I lost diabetes in 42 days’. -no need to buy it, just read the ‘look inside’. The secret is fasting while using allopurinol to stop hunger pains and protect the liver.

  • “Of course, if a high-quality, large-scale, randomized control trial showed conclusively that the risks of the low-carb, high-fat approach outweighed the benefit, as health professionals and scientists we would accept that.”

    Does that mean a clinician should give no diet advice until such an RCT appears? You say of the cholesterol hypothesis “This theory has been bolstered by decades of evidence ranging from epidemiological associations to genetic studies and interventional drug trials. There may be no better studied pathway in modern medicine.”
    You don’t mention that no existing cholesterol-lowering diet-heart RCT supports, or even bolsters, the cholesterol hypothesis.
    In other words, RCTs are one area where there there is little or no evidence (Mediterranean Diet trials to date have been thin, flawed, and subject to retraction or non-replication, but in any case are not really tests of the cholesterol hypothesis and sometimes contradict it).
    So what is left for guidance on diet?
    Nutritional epidemiology? You might as well shoot a passing bird, pull out its entrails, and ask what they can tell you – at least the bird was carrying less bias.
    Biomarker epidemiology? Here you at last have measurements not subject to recall error or bias from guilt or bragging, and you also have good feeding studies and RCTs that tell you what effects diets can have on biomarkers.
    A clinician could be excused for recommending the diet that in his or her opinion will have the most favourable effect on a patient’s biomarkers, then checking to see if it has worked.
    Once you go down this road, cholesterol and LDL-cholesterol are not stripped of all value, but they are diminished – no matter how large, they are only the foothills to the mountain range that is the ratio of TG to HDL or log[TG/HDL], the 2-hour insulin level after an OGTT, HbA1c, and the BMI which everyone mistakenly thinks is what any diet must be all about.
    Bring on the RCT, but don’t assume that everyone’s hands must be tied without it.

  • Three questions:
    Is it true that studies persons with cholesterol around 200 live longer? That Alzheimer’s patients die with very low cholesterol levels? That cholesterol lowering Stats affect cognition? If true please balance that for me.

  • There is sufficient evidence that cholesterol is a non-problem, made up by the sugar industry and drug companies that sell statins. Statins are poisons. Read “The big fat surprise” by Nina teicholz.

  • Time ago we truly believed that microbes were “spontaneously generating’ animalcules” and all our infections come from bad luck, sins, etc… Also, it is particularly hard to see the truth while your paycheck is coming from some corporation …

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