Have you resolved to eat healthy in 2018? Some approaches to eating may be more sustainable or healthier than others.
In its latest annual assessment of the year’s “Best Diets Overall,” U.S. News & World Report ranked the Whole30 and Keto diets at the bottom of the bunch.
Of the 40 diets assessed, the Whole30 diet was ranked in the bottom three.
The Keto diet was tied for last place with the Dukan diet.
In contrast, the DASH and Mediterranean diets were tied for first place.
According to the news service’s recent press release, the rankings were made by a panel of nutritionists, dietary consultants, and doctors that specialize in diabetes, heart health, and weight loss.
“Whether you're trying to lose weight or manage a chronic disease like diabetes, the 2018 Best Diets rankings are designed to help consumers identify the right diet for their specific needs,” Angela Haupt, assistant managing editor of health at U.S. News & World Report, said.
The organization also released rankings of the best commercial diets, weight-loss diets, plant-based diets, and several other categories of eating plans.
Why DASH and Mediterranean are ranked high
The DASH and Mediterranean diets have been ranked consistently high by the U.S. News & World Report for several years.
The DASH diet was designed to prevent and lower high blood pressure, a risk factor for heart disease and stroke.
The Mediterranean has also been associated with lower risk of cardiovascular disease as well as reduced incidence of cancer.
Both diets consist of eating plans that emphasize vegetables, fruits, whole grains, lean proteins, and low-fat dairy products.
Similarly, both diets limit saturated fats and refined sugars.
“I think the great thing about the DASH diet — and this is actually going to be true for the top three or four diets — is that there’s a tremendous amount of evidence behind it for its ability to lower chronic disease,” Kristin Kirkpatrick, MS, RD, LD, a licensed, registered dietitian who is manager of wellness nutrition services at the Cleveland Clinic Wellness Institute, told Healthline.
“It’s also very sustainable,” Kirkpatrick added. “I’m talking about the ability of someone to stay on it for longer than 30 days.”
Similarly, Katie Ferraro, MPH, RD, CDE, a registered dietitian and assistant clinical professor at the University of San Diego and the University of California San Francisco, highlighted the reduced incidence of chronic illness associated with the DASH and Mediterranean diets.
“If you look at those diets, the best ones overall are going to help you prevent a majority of chronic diseases, and one thing they have in common is a heavy reliance on produce,” Ferraro told Healthline.
“One of the things that I love about the DASH diet is that it’s between 7 and 10 servings of fruits and vegetables per day,” she added. “You’re so busy eating fruits and vegetables that you don’t have room to eat a bunch of crappier food.”
While Kirkpatrick and Ferraro agreed that the DASH and Mediterranean diets would be healthy choices for many people, they noted that no single diet is perfect for everyone.
For example, both of the top-ranked diets are high in carbohydrates, which might not be ideal for some people who are trying to lose weight or manage insulin resistance.
“If I look at something like the Mediterranean diet, for some type 2 diabetics, their carbs tend to go way too high. It doesn’t always help them,” Kirkpatrick said.
Dr. Priyanka Wali, a board-certified physician in California, expressed even stronger reservations about the suitability of a Mediterranean diet for people with diabetes.
“If someone has a history of diabetes, they should be on a very carbohydrate-restricted diet,” she told Healthline.
“I could never in good conscience tell someone who has diabetes to eat brown rice, which is part of the Mediterranean diet,” she continued, “because brown rice, regardless of the glycemic index, is loaded with carbs. And if you have diabetes, you’re very sensitive to carbohydrate intake.”
Whole30, Keto diets may be hard to follow
Compared to the DASH and Mediterranean diets, the Whole30, Dukan, and Keto diets are more restrictive in terms of the foods they limit.
This can make them harder to follow on a long-term basis.
“It’s too restrictive, and in that sense, it’s not sustainable,” Ferraro said about the Whole30 diet.
“Maybe you could get through this for 30 days, but if you think about all the data we have on behavior change and the effect on weight loss, you need to initiate lifestyle change if you want to achieve long-term results,” she continued.
Ferraro and Kirkpatrick suggested that the Keto diet may also be difficult for many people to follow, due in part to the extreme restrictions it puts on carbohydrate intake.
Both also raised concerns about the high fat content of the Keto diet as well as the lack of high-quality evidence about its use outside of certain subsets of patients.
Studies have found that a ketogenic diet is helpful for controlling seizures in patients with epilepsy.
But less research has been conducted on many other groups of people for whom a ketogenic diet might appeal.
“I found this when I spoke with physicians around the country. They’re dying to get the evidence, but we don’t have it yet,” Kirkpatrick said.
“If you’re a type 2 diabetic, is the Keto diet going to reverse it? It might, but we don’t have enough studies to show that yet,” she continued.
In contrast, Wali expressed more support for the Keto diet in people with diabetes and other conditions associated with insulin resistance.
“I think it’s actually a very important tool, specifically for people who have medical issues like diabetes, prediabetes, polycystic ovary syndrome, and fatty liver. Those are all indications that you basically have insulin resistance, meaning that your body’s hormone levels are imbalanced as a result of your diet,” Wali said.
Wali noted that other factos can also contribute to insulin resistance, including genetic predisposition, sleep patterns, and stress. She said many of her patients have successfully followed a ketogenic diet for years.
To support its use, she pointed to a review article published in 2015 in the journal Nutrition, which found that carbohydrate restriction reduces high blood glucose in people with type 2 diabetes.
Another recent review article in BMJ Open Diabetes Research & Care found that low to moderate carbohydrate diets have a greater effect on glycemic control in type 2 diabetes than high carbohydrate diets.
“But again, that’s not to say Keto’s for the world because not everybody has those conditions. Some people can eat a ton of carbs and don’t have any adverse effects,” Wali added.
Diets should be individualized
Kirkpatrick, Ferraro, and Wali provided different perspectives on the U.S. News and World Report’s diet rankings.
Ferraro suggested that the ranking can provide useful guidance to patients and providers.
In contrast, Wali argued “the idea of ranking diets is actually quite bogus.”
However, all agreed on one point: There is no one-size-fits-all approach to healthy eating.
They suggested that it’s best to limit sugar and other refined carbohydrates.
Beyond that, they encouraged readers to make an appointment with their doctor or dietitian to develop an eating plan that works for them.
This plan should take into account their individual medical histories, risk factors for chronic illness, food preferences, and goals.