U.S. News' Rankings are Losing Medical, Law Schools. Is “Best Diets” Next?

It's not just Harvard and Yale that are pulling out of U.S. News' Rankings; Dieters should, too.

This week, Harvard Medical School pulled out of the U.S. News & World Report rankings, citing in part longstanding concerns with the methodology behind the ratings. This blow to the magazine comes on the heels of a decision last fall by top law school deans, including those from Harvard and Yale, to withdraw from the U.S. News rankings over methodology issues for their schools. Are the U.S. News “Best Diets” any better? After a long, lucrative run, ranking everything from colleges to cruise ships, U.S. News has in recent years faced growing scrutiny and criticism of their lists. The magazine tried to appease law schools this month by making rankings changes, but it has yet to respond to expressions of concern by hundreds of doctors and others about how the annual “Best Diets” list also has serious problems and is the product of scant scientific backing.

With more than 43% of the nation suffering from obesity and the government projecting a 700% increase in diabetes among young people, under the age of 20 by 2060, the public is desperately in need of sound, evidence-based advice on how to eat.

Many of the U.S. News “Best Diets,” however, have barely been tested in clinical trials, the kind of rigorous evidence that is essential for showing cause-and-effect relationships. For example, a search for the science behind the “flexitarian” diet, tied for the magazine’s second-best “overall diet,” turned up only two clinical trials, on a total of 157 people, with no evidence for weight loss.

Searches on the “Mayo Clinic diet,” “Dr. Weil,” Nutritarian and Optavia, rated at #6, #9, #14, and #21 by U.S. News respectively, all turned up zero clinical trials. A search for the “Volumetrics Diet,” tied for 6th place, yielded a single 6-week trial supported by the Kellogg Company, finding that ready-to-eat cereals are a good way to lose weight.

Meanwhile, U.S. News experts this year inexplicably resurrected the Pritikin diet, a low-fat throwback from the 1970s that hasn’t been tested since 1983, in a trial that was designed to look at the effect on peripheral vascular disease--and showed no benefit.

By contrast, a low-carbohydrate diet, which has not made even an appearance on the “Best Diet” list in years, shows 1,910 clinical trial papers published to date. Other diets that similarly cut back on sugars, starches, and other carbohydrates, such as ketogenic (“keto”) and Atkins, both perennial U.S. News flunkees, turned up 456 and 169 papers, respectively (some may be multiple papers on the same trial).

Of course numbers aren’t everything, but virtually every head-to-head diet study has found that low-carb dieters lose more weight than those on low-fat, in addition to seeing more or equal improvement in most heart disease risk factors.

These are no longer preliminary results. When I co-authored an op-ed critiquing the U.S. News list in 2018, ample data already existed to argue that low-carbohydrate diets should not be relegated as U.S. News “Best Diets” bottom dwellers. Now, five years later, the medical literature on this nutritional approach has ballooned to the point where stiffing this option is no longer scientifically credible.

What explains the disconnect between the evidence and the rankings? It’s hard to know, because the magazine’s criteria for rating diets are inscrutable. U.S. News says that an expert panel answered “over 40 questions” on each diet, yet only 10 are listed on its website, a lack of transparency that makes replication impossible.

Further, readers aren’t told how much value is placed on each question. For instance, does a diet rank highly because panelists thought it could be “easily adapted for the whole family” or perhaps “modified to meet cultural, religious or personal preferences?” as some questions asked? Or rather, was the diet chosen due to its effect on weight loss? Many people might prioritize the latter—yet they can’t know how that goal, compared to others, is factored into a diet’s overall ranking.

This is an unstable methodology which has evidently yielded volatile rankings. In fact, nearly one fifth of diets on the 2022 list, including Fertility, Engine 2, Biggest Loser, Alkaline, Sirtfood Autoimmune Protocol, and Whole30 fell out of the rankings altogether one year later, in 2023. The popular Whole30 diet, U.S. News readers now learn, is a “fad” that is “not necessarily recommended by experts.”

The ranking process has clearly lacked objective standards. According to experts who participated in the process, they were simply asked to rate questions on a scale of 1-to-5, based on their opinion of each diet. It’s a subjective approach and obviously open to bias.

No doubt a person’s bias can be hard to discern. Last year, nearly a third of the magazine’s expert panel were members of a vegan advocacy group whose tactics were reported in the Journal of the American Medical Association to be called more “vitriolic” than those of the National Rifle Association. Five members of that group remain on this year’s panel, which otherwise includes an advisor to the California Prune Board and a consultant to “many US Commodity Boards including Potatoes USA.” About 40% of the panel is noted to have a university position of some kind.

Hundreds of doctors in recent years have signed letters to U.S. News, asking its editors to recognize a new generation of scientific literature on low-carbohydrate diets and not to rely on vegan or animal-rights activists for expert opinion on healthy diets for humans.

Unlike the law school deans from Harvard and Yale, however, these doctors and other critics have been unable to gain the ear of U.S. News editors. Do the 93% of Americans reportedly challenged by obesity, diabetes and other diet-related diseases not deserve as much transparency about their options as our elite law students? It’s time to give our nation’s confused, misinformed dieters the clarity of choice they deserve.