Every year in January, U.S. News & World Report publishes a cover story on what its experts consider the ‘best’ diets. The magazine consistently ranks two high-carbohydrate, low-fat diets, “DASH” and Mediterranean, at the top of its list despite the razor-thin base of rigorous evidence supporting health benefits for either of these.
The U.S. News ranking, which faithfully mimics the federal government’s own U.S. Dietary Guidelines for Americans, is outdated at best and a failure at worst, considering the state of our nation’s health. Both are a one-size-fits-all approach to nutrition that has been unsuccessful in preventing our current epidemics of metabolic disease, now impacting nearly 90 percent of Americans, according to a recent study by University of North Carolina.
In reality, there is no one ‘best’ diet. Nutritional recommendations cannot be made without taking into account the widely varying state of each person's health as well as differences in age, gender and genetic background.
These points were highlighted by Nina Teicholz, executive director of the Nutrition Coalition, and Gary Taubes, author and science journalist, in an op-ed for the Los Angeles Times last year when U.S. News published virtually the same list. Teicholz and Taubes wrote that while the federal government has promoted these diets for decades, “the evidence still falls far short of demonstrating a significant impact on the major nutrition-related diseases of our time, especially obesity and diabetes.”
The L.A. Times article noted that authoritative reviews have found that DASH has been tested on only 2,000 subjects in studies lasting no longer than six months and that therefore, its effects can hardly be generalized to all Americans. Studies on the Mediterranean diet reveal it has very little impact on overall mortality or weight loss.
Americans have been directed to follow various versions of the low-fat diet since the Dietary Guidelines were first introduced in 1980. And the nation has largely complied, eating more grains, vegetables and fruits while consuming less whole milk, meat and eggs, according to the best available government data, from USDA.
It is crucial that federal officials authoring the 2020 Dietary Guidelines pay attention to the latest science. Conventional thinking about healthy eating has been unable to combat steady rises in nutrition-related conditions, including obesity, diabetes, fatty liver disease, cardiovascular disease and more.
The Dietary Guidelines need to be reformed so they are based on the most rigorous scientific data and offer a diverse range of dietary patterns. Only then will Americans be informed about how to eat for better health.
 "Dietary Approaches to Stop Hypertension"
 DASH is the same as the "US-Style Dietary Pattern" recommended by the DGA, and "Mediterranean" is another DGA "Dietary Pattern;" The third DGA pattern is "Vegetarian," which is also low in fat and high in carbohydrates. All three patterns recommend 31-33% fat and 50-55% carbohydrates.
 Joana Araújo, Jianwen Cai, and June Stevens.Metabolic Syndrome and Related Disorders. http://doi.org/10.1089/met.2018.0105