The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Fit or Fad: Diet Ratings for New Year’s Resolutions

Posted in

Wednesday, Jan 09, 2019

Every year, many of us resolve to start a new diet or fitness plan, stop smoking, drink more water, and generally make better choices to improve our health. Nearly 70% of American adults are overweight or obese* even though an estimated 45 million Americans are dieting. It’s no wonder why weight loss is one of the most popular New Year’s resolutions, and there is no shortage of diet plans and gimmicks on the market. While some of these diets are questionable at best, there are some that are safe, nutritious, heart-healthy, and effective for weight loss. So which diet is the best for weight loss and lifelong weight management?

The 2019 U.S. News and World Report Best Diets ratings have recently been published. This year, their team of experts rate the effectiveness of 41 different diets in the following areas: easy to follow, nutritious, safe, effective for weight loss, and protective against diabetes and heart disease. Each of the areas was rated on a scale of 1-5 stars with 1 being the worst and 5 being the best.

There were several different categories of best diets, including best diets overall, best weight loss diets, best diets for healthy eating, best heart-healthy diets, and easiest diets to follow.

Best Diets Overall:


  • Mediterranean Diet: This diet emphasizes fruits, vegetables, olive oil, whole grains, fish and other heart healthy foods.

  • DASH Diet:  The dietary approaches for hypertension (DASH) focuses on fruits, veggies, whole grains, lean protein and low-fat dairy to control blood pressure and is praised for being nutritionally sound and safe.

  • Flexitarian Diet:  flexible vegetarian emphasizes fruits, veggies, whole grains and plant-based protein

Worst Diets Overall


  • Ketogenic Diet (tied w/ Whole30): While unrelated to each other in their approaches, both popular diets were criticized for being too restrictive, nutritionally incomplete, potentially dangerous, and not sustainable for the long-term.   

  • Body Reset Diet: This 15-day smoothie diet was called an unhealthy weight loss gimmick by most reviewers that fails to teach any life skills for sustainable weight loss

  • Dukan Diet: Similar to the Keto diet, this low-carb diet was criticized for being nutritionally incomplete, too restrictive and even dangerous for people with diabetes or heart disease.    

How Diets Were Ranked

The diets were evaluated by a panel of nationally recognized experts in diet, nutrition, obesity, food psychology, diabetes, and heart disease. After undergoing intense scrutiny from the experts, the 41 diets that were evaluated were ranked in several categories, including:

  • Best Diets Overall

  • Best Commercial Diets

  • Best Weight-Loss Diets

  • Best Diabetes Diets

  • Best Heart-Healthy Diets

  • Best Diets for Healthy Eating

  • Easiest Diets to Follow

  • Best Plant-Based Diets

  • Best Fast Weight-Loss Diets


The Cooper Institute strongly supports the Mediterranean and the DASH diets because they are evidence-based and nutritionally sound, as well as the Flexitarian diet for vegetarians. These diets are in line with the 2015-2020 Dietary Guidelines for Americans as well as dietary recommendations from the American Heart Association, American Cancer Society, American Diabetes Association, and more.

The DASH diet has been shown time and time again to be an effective strategy for lowering both resting blood pressure and LDL (bad) cholesterol. The MIND diet is also a good choice because it basically combines the Mediterranean and DASH diets into one plan.

As for other diets like Keto, Paleo, and Whole30, we do not recommend them for most individuals because they lack key nutrients, fiber and phytochemicals. Aside from the fact that these types of food restrictive or elimination diets are too difficult for most people to stick with, there is no evidence that they lead to long-term weight control, decreased morbidity or decreased mortality outcomes.

Finding the right diet for your lifestyle can be the key to long-term weight loss and weight management. When combined with regular physical activity, avoidance of tobacco, and regular check-ups, you have a recipe for a long and healthy life.
View the full list of diets from U.S. News & World Report to explore all of the categories, to learn more, and to find the diet plan that is right for you.  

*Overweight in adults is defined as a body mass index (BMI) between 25.0 and 29.9 kg/m2, while obesity is defined as a BMI greater than or equal to 30 kg/m2. Use this link to calculate your BMI. Please note that BMI is not a valid indicator of body weight status for individuals who are extremely muscular. However, such individuals make up only a tiny portion of the U.S. population.