Two of the most buzzed-about diets, the Keto diet and the Whole30 diet, have landed at the bottom of a new ranking of best diets for 2018.
The Keto diet, which promotes a low-carbohydrate, high-fat regimen, tied for last on the Best Diet Overall list released today by U.S. News and World Report.
"One of our experts said, ‘Any diet that recommends snacking on bacon can’t be taken seriously as a health-promoting way to eat,'" Angela Haupt, assistant managing editor of health at U.S. News and World Report, told ABC News.
Ketogenic, or low-carbohydrate diets, have been used for treatment of epilepsy for decades and more recently gained attention as a tool for weight loss. Severely restricting carbohydrates can result in a process called ketosis.
"One of the concerns with Keto is how high in saturated fat it is," Haupt said. "Our experts say the diet can be especially dangerous to people with severe diabetes, kidney disease and heart disease."
The Whole30 diet, which gets 60,000 searches per month in Google, came in next to last in the ranking of 40 diet plans. The diet, based on a bestselling book, strips food groups like sugar, grains, dairy and legumes from participants’ diets for a full 30 days, according to its website.
The expert panel of nutritionists, dietary consultants and physicians that ranked the diets criticized Whole30 in particular, along with the Body Reset diet, for “being ‘fad diets’ that unnecessarily wipe out entire food groups,” according to U.S. News and World Report.
"The main thing about [Whole30 and Keto diets] is they’re both extreme," Haupt said. "They’re both really restrictive, in some cases wiping out entire food groups, and our experts say it’s just not necessary and it’s not safe or healthy.
"You’re just not setting yourself up for any type of lasting, healthy, long-term success and you might even do damage to yourself in the process," she added.
Topping the list of best diets for 2018 were the Mediterranean Diet and the DASH Diet, which tied for first place.
"Both of them are really nutritionally sound," Haupt said. "And they also have benefits for chronic diseases and even brain health and heart health."
Haupt said a desire for drastic change and fast results could explain why diets like Whole30 and Keto have reached such popularity.
"Slow and steady might work but it’s not the exciting way to go about things and weight loss can be so frustrating," Haupt said. "You might not see it as quickly but you are setting yourself up for longer, more healthy success when you do choose that sound plan."
Diet trends in 2018 will focus on promoting health from the inside out, according to U.S. News and World Report. The magazine reports consumers are interested in eating for whole body health as well as for specific body systems, like skin, muscles, bones, and a healthy nervous system.
Here is a breakdown of the diets that rounded out the top five in U.S. News and World Report's 2018 Best Diets ranking.
1. Mediterranean and DASH diets
The Mediterranean diet, which features meals high in "good" fats, ranked as the top diet on the U.S. News and World Report's ranking for the first time ever, in a tie with the DASH diet.
The Mediterranean diet recommends emulating how people in the Mediterranean region have traditionally eaten, with a focus on foods like olive oil, fish and vegetables. U.S. News and World Report called the diet a "well-balanced eating plan" and pointed to research that suggests the diet helps prevent some chronic diseases and increases longevity.
The DASH diet has been ranked as the No. 1 overall diet by U.S. News and World Report for eight consecutive rankings.
Originally started by the National Heart, Lung, and Blood Institute (NHLBI) as a diet to help reduce blood pressure, the DASH diet is made up of low-sodium and healthful foods. The NHLBI publishes free guides on the plan so you can see if it is right for you.
"The thing about the DASH diet is you’re eating specifically the foods you’ve always been told to eat, pretty much fruit, vegetables, whole grain, lean protein and low-fat dairy," Haupt said. "And it eliminates foods high in fat and sugar-sweetened drinks and sweets."
3. Flexitarian diet
The flexitarian diet encourages people to try alternative meat options, like tofu, but leaves room for flexibility if you can't quite fully give up meat. The diet was promoted by dietitian Dawn Jackson Blatner in a 2009 book that says you can reap the benefits of a plant-heavy diet even if you eat meat occasionally, according to U.S. News and World Report.
This plant-heavy diet focuses on adding five food groups -- "new meat," fruits and vegetables, whole grains, dairy and sugar and spices -- to your diet, instead of taking foods away. The "new meat" food group includes tofu, beans, lentils, peas, nuts and seeds and eggs, according to U.S. News and World Report.
Weight Watchers ranked in the top five for best diets overall and also obtained the No. 1 ranking for best commercial diets and best fast weight-loss diets this year.
The program, which is backed by Oprah Winfrey, focuses on assigning points based on the nutritional value of foods.
Weight Watchers, which offers support online and with in-person group meetings, assigns a points value to foods to encourage dieters to make healthful choices that will "fill" you up. The points are higher for foods high in saturated fats and sugars, and lower for foods with high levels of protein.
5. MIND, TLC and Volumetrics diets
The No. 5 spot in U.S. News and World Report's latest ranking is a three-way tie between the MIND Diet, TLC Diet and Volumetrics.
The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet, ranked third last year, is a hybrid of the top-rated DASH and Mediterranean diets.
The diet focuses on "10 brain-healthy food groups: green leafy vegetables in particular, all other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil and wine," according to U.S. News and World Report.
Among the diet's requirements is eating three servings of whole grains, a salad and another vegetable daily, as well as a single glass of wine if desired.
The Therapeutic Lifestyle Changes (TLC) diet was designed to help cut bad cholesterol and requires eating foods with less saturated fat.
The diet limits daily cholesterol intake while pushing more foods with fiber in order to help dieters manage high cholesterol without medication, according to U.S. News and World Report.
The Volumetrics diet is described as less of a diet and more of an approach to eating by U.S. News and World Report.
The diet, promoted by Penn State University nutrition professor Barbara Rolls, teaches you to, "decipher a food's energy density, cut the energy density of your meals and make choices that fight hunger," the magazine reports.
Gillian Mohney contributed to this report.