In 2021, as ever, the best diets are simple

Every year, as millions of people around the world forge new resolutions to eat healthier and lose weight, US News & World Report releases a conveniently timed ranking of the best diets. A panel of experts in obesity, nutrition, diabetes, heart disease, and food psychology rigorously rate each of 39 diets on seven criteria:

a box filled with different types of food: Each of these servings is quite large, but they're full of healthy grains and veggies.

© Provided by Popular Science
Each of these servings is quite large, but they’re full of healthy grains and veggies.

a box filled with different types of food: Each of these servings is quite large, but they're full of healthy grains and veggies.

© Ella Olsson/Pexels
Each of these servings is quite large, but they’re full of healthy grains and veggies.

  • Likelihood of losing significant weight in the first 12 months
  • Likelihood of losing significant weight over two years or more
  • Effectiveness for preventing diabetes (or as a maintenance diet)
  • Effectiveness for preventing heart disease (or for reducing risk for heart patients)
  • How easy it is to follow
  • Nutritional completeness
  • Health risks (like malnourishment, too-rapid weight loss, or specific nutrient deficiencies)

chart, funnel chart: Your mileage may vary, so to speak.

© Infographic by Sara Chodosh
Your mileage may vary, so to speak.

For 2021, as for every year, many of the most popular diets fared pretty badly. The keto diet was tied for second to last, with Whole30 just above it. Atkins ranked one better than that, and Paleo wasn’t far above Atkins. Veganism tied for 17th, while vegetarianism snagged a three-way tie for ninth.

The top spots all went to diets with two key things in common: variety and an emphasis on whole foods. Here are the top five (including some ties!):

1. Mediterranean diet

Emphasis on fruits, veggies, whole grains, olive oil, beans, nuts, legumes, fish and other seafood. Eggs, cheese, and yogurt can be eaten in moderation. Keep red meats and sugar as treats.

2. DASH (dietary approaches to stop hypertension) diet — TIE

Eat lots of fruits, veggies, lean protein, whole grains, and low-fat dairy. Avoid saturated fats and sugar.

2. Flexitarian diet — TIE

Be a vegetarian most of the time. Swap in beans, peas, or eggs for meats, and consume plenty of fruits, veggies, and whole grains. You can look up more details because there’s actually a full meal plan involving breakfast, lunch, dinner, and two snacks to add up to a total 1500 calories per day. But feel free to also just swap in flexitarian meals ad hoc.

4. Weight Watchers

The first actual paid program on the list, WW uses a points system to guide dieters towards foods lower in sugar, saturated fat, and overall calories while consuming slightly more protein. There are a variety of paid WW plans, with the lowest being about $20 per month.

5. Mayo Clinic diet — TIE

A two-part system, with part one (‘Lose it!’) involving adding a healthy breakfast (i.e. fruits, veggies, whole grains, healthy fats) plus 30 minutes of exercise per day. You’re not allowed to eat while watching TV or consume sugar except what’s naturally found in fruit. Meat is only allowed in limited quantities, as is full-fat dairy. The second phase (‘Live it!’) is basically the first phase but with more flexibility. You aren’t realistically going to cut out sugar forever, and the Mayo Clinic diet acknowledges that. So the long term plan involves lots of whole grains, fruits, veggies, and healthy fats. Less saturated fats and sugar.

5. MIND (Mediterranean-DASH intervention for neurodegenerative delay) diet — TIE

A combination of the DASH and Mediterrean diets that selects for all the things meant to boost brain health. You eat at least three servings of whole grains per day, plus a salad, one vegetable, and one glass of wine. Snacks consist mainly of nuts, and every other day you’re supposed to consume half a cup of beans. Poultry, berries, and fish also get mixed in.

5. TLC (therapeutic lifestyle changes) diet — TIE

An extremely open-ended diet, the main idea here is to cut overall calories while focusing on eating less saturated fat and cholesterol (plus eating more fiber). The goal is 2,500 calories a day for men or 1,800 for women—less if you want to lose weight as well as lower cholesterol (which is what the diet was created for).

5. Volumetrics diet — TIE

The idea here is to pick foods with low energy density. Cookies and chips, for instance, pack a lot of calories into a small portion size, which means it’s easy to eat a lot of them and not feel full. Fruits and vegetables, in contrast, are very filling in comparison to how few calories (and nutrients!) they contain. Volumetrics splits food up into four categories from least to most energy dense, where you’re meant to eat mainly foods from categories one and two (think vegetables, grains, low-fat meats, and beans). Category three (fattier meat, cheeses, cake, salad dressing) should be eaten in moderation, while category four (chips, candy, nuts, butter, cookies) should be mostly avoided.

You may not have even heard of a lot of these diets, but they should be household names. These—not the fad diets—should be the kind of diets we all follow. But the main problem might just be that we probably wouldn’t think of a lot of these as “diets.” Essentially all of the top-rated plans here are more like eating guidelines. They involve having a variety of foods, with an emphasis on fruits, vegetables, whole grains, and other unprocessed foods.

chart, funnel chart: Your mileage may vary, so to speak.

© Provided by Popular Science
Your mileage may vary, so to speak.

A lot of people are more familiar with diets as something you go on temporarily in order to lose weight. But for that reason, many of the popular diets fare badly on this ranking. Crash diets generally rely on heavily restricting one type of food, be it carbs or fat, which works in the short term mainly because you end up consuming fewer calories overall. Over a longer period of time, though, it’s very difficult to stick to such an extreme diet. And that’s not to mention the fact that you can develop nutritional deficiencies from cutting out certain foods entirely (the main reason veganism is so low on the rankings).

There’s also the small, complicating matter that everyone responds to diets differently.

The graph to the right is from a study in JAMA following overweight adults for a full year as they adhered to the two different diets, low fat or low carb. As you can see, most people lost weight—on average, about 11 or 12 pounds. In fact, across all diet studies people generally lose around five to seven pounds over the course of a year, regardless of the balance of macronutrients. That means that the best advice on which diet to pick is this: choose the one you’ll stick to.

Really, the best way to lose weight is also—conveniently—the best way to be healthy: eat a balanced diet full of whole, unprocessed foods. Choose brown rice over white bread. Pick roasted carrots over a juice blend. But also, have a cupcake sometimes.

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