An editorial published recently by the British Medical Journal makes a compelling case.
In fact, it should be required reading for every physician, and everyone concerned about weight and diabetes.
The authors provide persuasive evidence that America's widespread intake imbalance between omega-6 and omega-3 fats promotes obesity and diabetes.
They explain why we need to restore the omega-6/omega-3 intake balance found throughout almost all of human history, and abandon the clearly futile obsession with exercise and calorie-cutting.
Drs. Artemis Simopoulos and James DiNicolantonio put it this way in their editorial, which was published in the BMJ journal Open Heart: “The concept of ‘a calorie is a calorie', [has] led to the development of a huge weight loss industry, and books promoting ‘eat less and exercise more'.”
As they wrote, “These approaches continue to be espoused today, despite the scientific evidence that ‘a calorie is not a calorie', and that the sources of calories are important in influencing human metabolism and appetite control.”
(You'll find the authors' abridged biographies at the end of this article, which display their exceptional qualifications and experience in this realm.)
Underscoring its futility, the medical community's narrow focus on calorie-cutting and exercise as the key weight control tools hasn't helped the 1.5 billion overweight and 500 million obese people worldwide.
Omega-3/6 balance and weight gain: The story so far
By now, it's very clear that omega-6 fatty acids promote weight gain.
For example, see Excess Omega-6 Fat Intakes Promote Weight Gain, and Omega-6 Fats Drive Obesity; Omega-3s Help.
But the clinical evidence that diets rich in omega-3s produce weight loss in people is modest and somewhat mixed, falling short of being conclusive.
For past coverage of this topic, see Omega-3s Linked to Healthier Weight and Body Composition, Fish Oil Lowers Cortisol and Body Fat Levels, Weight Loss Efforts Aided by Omega-3s, Omega-3s Boost Weight Loss Benefits of Low-Cal Diets, Weight Loss Lacking in Omega-3 Trial, and Omega-3s Linked to Healthier Weight and Body Composition.
However, the negative studies typically failed to account for people's omega-6 intakes. And in one case, researchers tested a fish oil that contained an unnaturally low proportion of omega-3 DHA, which, in animal weight control studies, has been more effective than omega-3 EPA (these are the two major omega-3s in fish fat).
However, none of the positive clinical studies have been substantial enough to produce reliable results, which is why experts in the field continually call for funding of more robust trials.
Unfortunately, it's near-impossible to obtain the hundreds of millions of dollars needed to conduct large, lengthy trials designed to test non-patentable nutritional supplements like fish oil.
How America's omega-6/omega-3 imbalance promotes weight gain
Omega-3 and omega-6 fatty acids strongly influence food intake and the sensitivity of the hormones involved in blood sugar control (insulin) and appetite suppression (leptin).
Excessive omega-6 fat intake promotes inflammation and raises the risk of blood clotting, while boosting production of white fat that gets stored around the abdomen, rather than “good” energy-burning brown fat, production of which dietary omega-3s tend to promote.
And excess white belly fat fuels and sustains chronic inflammation, which in turn promotes obesity, diabetes, dementia, cardiovascular disease, and cancer.
Throughout human history, people consumed about one-part omega-6s to one-part omega-3s fats, and at most, we consumed four-parts omega-6s is to one-part omega-3s.
Sadly, as Drs. Simopoulos and DiNicolantonio point out, that dietary ratio now averages a belt-busting 16 parts omega-6 fats to one part omega-3s.
Accordingly, as they wrote, “The time has come to return the omega-3 fatty acids in the food supply and decrease the omega-6 fatty acids by changing the cooking oils and eating less meat and more fish.”
New smoking gun: Women's Health Study
Even though omega-3s haven't produced significant weight loss in clinical trials, they have often reduced participants' waist circumferences and waist-hip ratios, and positive metabolic changes.
Taken together, those effects suggest that — all other things being equal — diets rich in omega-3s should help discourage weight gain.
And as Drs. Simopoulos and DiNicolantonio noted, when so-called “Fat-1” mice — animals genetically engineered to produce high levels of omega-3s — were fed high-fat/calorie diets, they didn't develop the obesity, diabetes, high cholesterol levels, and fatty livers that would have afflicted regular rodents.
More importantly, their case is bolstered by a very recent analysis of data from the Women's Health Study (WHS), which involved 39,876 female health professionals (Wang L et al. 2016).
The WHS study — conducted by researchers from Harvard University and Boston's Brigham and Women's Hospital — centered on a 10-year clinical trial performed from 1993 to 2004, which tested the ability of aspirin and vitamin E to prevent cardiovascular disease and cancer.
The WHS study continued for another 10 years, through 2014, allowing researchers to collect more data from some of the participating women.
The recent analysis of WHS data compared omega-3 and omega-6 blood levels in 534 healthy participants to their weight gain or loss over a period of 10 years.
And tellingly, the new analysis linked two factors to greater risk of weight gain:
• Higher omega-6 blood levels
• Higher omega-6 to omega-3 ratios in the blood
In contrast, their analysis linked higher omega-3 blood levels to a reduced risk for weight gain.
The Harvard/Brigham group came to the inevitable conclusion: “… we found suggestive evidence that [omega-6 blood levels] may be positively associated, and [omega-3 blood levels] inversely associated with weight gain in initially normal-weight women.”
In plain language, their findings strongly suggest that higher omega-6 intakes promote weight gain, while higher omega-3 intakes discourage weight gain.
Since this effect only became clear in a study that lasted 10 years, the usual clinical trial isn't nearly long enough to reveal this weighty effect of America's omega imbalance.
As Drs. Simopoulos and DiNicolantonio said in their BMJ editorial, this WHS follow-up study is unusually credible, for a simple reason.
Most nutrition-health studies rely on people's notoriously inaccurate responses to diet questionnaires, and scientists' inevitably crude estimates of the participants' resulting intakes of nutrients such as omega-6s and omega-3s.
But the recent analysis out of Boston compared the participating women's actual blood levels of omega-6 and omega-3 fats to their weight gain over time.
In addition, as Dr. Simopoulos told us in an interview, the findings and conclusions of the Harvard/Brigham's research group are striking, because in the past they've dismissed concerns about Americans' high omega-6 fat intakes.
Given the weight of evidence that America's omega imbalance promotes weight gain, what should we do about it?
Omega-6 oils: The weight-gain problem hiding in your pantry
Since the 1940s, and especially since the late 1960s, Americans have typically consumed far more omega-6 fatty acids than humans ever did before.
That happened because of doctors' near-universal — but badly misguided — advice to reduce heart risks by replacing saturated animal fats (butter and lard) with polyunsaturated vegetable oils.
For more on that persistent myth, see False Advice on Fats?, Major Study Exonerates Saturated Fat, Heart-Diet Myths Get a Busting, and Are Vegetable Oils Heart Healthy?).
Over the past 75 years or so, most Americans' intake of vegetables and pasture-raised meats, poultry, eggs, and milk products — which provide small but significant amounts of omega-3s — fell substantially.
Diets rich in seafood — especially omega-3-rich fatty fish like salmon, tuna, and sardines — could substantially offset (not eliminate) the obesity-promoting impact of America's excessive omega-6 intake. But average U.S. seafood consumption is too low to make a real difference, and much of it is fish fried in omega-6-laden vegetable oils.
At the same time, livestock once raised on pasture, which contains small but significant amounts of omega-3s, were switched to omega-6 rich grains.
That change in livestock feed produced higher levels of omega-6 fats — and lower levels of omega-3s — in meat, poultry, eggs, and dairy products.
Importantly, the vegetable oils used by most Americans are extremely high in omega-6 fats.
Most packaged, take-out, restaurant, and prepared foods feature cheap oils that are very high in omega-6 fats, such as soy, palm, corn, cottonseed, and regular (i.e., not high-oleic) sunflower and safflower oils.
The situation in some people's kitchens has improved, thanks to rising use of oils relatively low in omega-6 fats: olive, canola, coconut, macadamia, and high-oleic sunflower and safflower oils.
High-oleic sunflower oil is only about 10% omega-6 fat, while mid-oleic sunflower is about 25% omega-6 fat, versus about 90% in standard sunflower oil.
Hi-oleic safflower oil has more omega-6 fat than high-oleic sunflower oil, but it's better than regular safflower oil. (You may have to visit a natural food store to find brands oils that disclose the oleic acid content of their sunflower and safflower oils.
Healthy omega balance: One key to staying slim
The editorial by Drs. Simopoulos and DiNicolantonio included clear advice for food makers, rule makers, and health authorities:
“It is the responsibility of governments and international organizations to establish nutrition policies based on science and not continue along the same path of focusing exclusively on calories and energy expenditure, which have failed miserably over the past 30 years.”
To that we say, “amen”.
About the editorial's authors
Artemis Simopoulos, M.D., was a founding member of the International Society for the Study of Fatty Acids and Lipids (ISSFAL) and is the founder and president of the International Society of Nutrigenetics/ Nutrigenomics (ISNN).
A graduate of the Boston University School of Medicine, she is a physician and endocrinologist whose research at the National Institutes of Health (NIH) focused on the nutritional aspects of genetic and endocrine disorders and evolutionary aspects of diet and fatty acids, including the health effects of intake ratios of omega-6 and omega-3 fatty acids.
Dr. Simopoulos and has edited numerous books and journal supplements, in addition to publishing over 300 scientific papers, and for lay readers, she wrote The Omega Diet: The Lifesaving Nutritional Program Based on the Best of the Mediterranean Diets (HarperCollins, 1999).
James DiNicolantonio, Pharm.D. > https://www.saintlukeshealthsystem.org/dinicolantonio < is a cardiovascular research scientist at the Saint Luke's Mid America Heart Institute. His research focuses on cardiovascular health, diabetes, obesity, hypertension, lipids, anti-clotting agents, as well as nutrition and nutritional supplements. He's the author or co-author of more than 120 medical publications, and penned a widely cited opinion piece in The New York Times, concerning the consequences of sugar addiction (“Sugar Season. It's Everywhere, and Addictive".).