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Understanding America’s Most Popular Diets

There are almost as many types of diets as there are types of foods. We help you find the one that’s right for you, with healthy and delicious recipes you'll be excited to serve.

Whether you’re trying to lose the “COVID 15” or a larger amount of weight, or just trying to improve your health and wellness, you’ll likely have to start by changing your eating habits. But knowing exactly what to change seems easier said than done. Experts used to say the solution was obvious: go on a low-calorie diet. These days healthy eating can look different to you than it does to your neighbor, and fad diets only confuse the matter. Should you eat according to your blood type, or go on a low-fat diet? Should you try giving up one (or more) food groups or simply change when you eat? In the end, there is no one-size-fits-all answer: The answer to “what diets work best?” is as personal as your fingerprint.

Different types of diets

There are literally dozens of diet plans out there. Some will tell you precisely what to eat, while others offer more leeway, with wider guardrails. Let’s take a look at six of the most popular diets for 2021 — how they work, what you can eat while following them, and what the research says about their effectiveness.

Jump ahead to: 

Mediterranean diet >>

Intermittent fasting >>

Keto diet >>

Paleo diet >>

Vegetarian diet >>

Vegan diet >>

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Mediterranean diet

Ranked for the last four years as the #1 best diet overall by U.S. News & World Report, the Mediterranean diet is more of an eating plan than a diet program. Years ago, researchers figured out that people who live in the Mediterranean region lived longer and had lower rates of heart disease, type 2 diabetes, and cancer than we do in America. That’s because of their more active lifestyle as well as their eating pattern, which features minimally processed, largely plant-based foods

What is the Mediterranean diet?

Picture yourself at a taverna on a sunny Greek isle. What’s on the table? Odds are you’ll find dishes made with plenty of olive oil, fresh vegetables, legumes and beans, whole grains, fish, nuts and seeds, and dairy like feta cheese used as an accent. Delicious, but also high in fiber, lean protein, and antioxidants — a perfectly healthy diet. You’ll feel satisfied for longer, which helps you eat less (and lose weight), while also improving your health.

What can you eat on the Mediterranean diet?

Base your meals on nutrient-rich foods like fruits and vegetables, whole grains, beans, legumes, nuts, and seeds. Use extra-virgin olive oil, herbs, and spices generously, and eat seafood regularly. Have poultry, eggs, cheese, yogurt, and red wine in moderate amounts. Save red meat and sweets for when you really have a craving. And try to avoid highly processed foods completely.

What are the health benefits of the Mediterranean diet?

Decades of research shows that the Mediterranean diet is a way to lower your risk of multiple chronic — and life-threatening — diseases. Those include cardiovascular disease, stroke, metabolic diseases like diabetes, high blood pressure, cancer, Alzheimer’s, and Parkinson’s disease. The diet’s large amounts of fiber and lean protein can also help with weight loss. 

Who is the Mediterranean diet for?

This eating pattern works for virtually anyone. It’s especially useful if you have a history (or family history) of cardiovascular disease, high blood pressure, high cholesterol, or type 2 diabetes.

Who should not go on the Mediterranean diet?

This eating plan poses very few risks — there’s no reason not to try it. 

Want to explore the Mediterranean diet? Try these recipes:

Easy Sheet Pan Greek Chicken

This easy, one-bowl (and one-pan) dinner is perfectly Mediterranean. It features lean chicken breasts, plenty of vegetables like grape tomatoes and artichoke hearts, olive oil, and herbs, with just a sprinkling of salty, creamy feta for contrast. Pour a glass of red wine and you’re all set.


Intermittent fasting

In its 2020 Food and Health Survey of Americans, the International Food Information Council found that intermittent fasting was the most popular diet being followed. But it’s not just popular — research suggests it can help you lose weight and improve your health. 

What is intermittent fasting?

Have you ever had to stop eating after dinner for blood tests the next day? That’s the basic idea of intermittent fasting — you simply don’t eat for a set period of time, on a regular basis. You might eat only during certain hours every day, or eat normally most days and just one meal on others. 

What can you eat during intermittent fasting?

During the hours while you’re fasting, you’ll only have water and non-caloric drinks like black coffee or tea. When you do eat, forget about heavily processed foods or trips to the drive-thru. You’ll be choosing nutrient-dense (but still tasty) meals, and you probably won’t have to drastically change your eating habits.

What are the health benefits of intermittent fasting?

Much of the research into intermittent fasting has been performed on rats — so the findings may not fully translate for humans. But there is evidence that intermittent fasting can be as effective for weight loss as a low-calorie diet. Studies have also found that it can help control your blood sugar and your blood pressure, and lower your cholesterol levels. Research into the long-term effects is still slim, but it may also lower both inflammation and your risk of cancer.

Who is intermittent fasting for?

If you struggle with diet plans that spell out exactly what you should eat, intermittent fasting might be a good choice for you. All you really need to focus on is timing.

Who should not try intermittent fasting?

Check with your doctor before starting if:

  • You have diabetes

  • You have low blood pressure

  • You’re on medication that has to be taken with food

  • You’re doing intense workouts like CrossFit or training for a marathon

  • You’re pregnant or breastfeeding, or trying to conceive

  • You have a history of eating disorders

Want to explore intermittent fasting? Try these recipes:

Winter Vegetable Grain Bowl

When you won’t be eating again for hours, you want to make sure your meal is as filling as it is delicious. These family-friendly bowls start with fiber- and protein-packed quinoa and farro. That gets topped with roasted vegetables (whatever kind you have will do) and a soft-boiled egg. Drizzle the bowl with tart and tangy ponzu sauce, and you’ll be satisfied until the next time you eat.


Keto diet

It’s popular, but is it safe? This high-fat, low-carb diet has spawned best-selling cookbooks, celebrity endorsements, and more than a little controversy. Of the 39 diets examined by U.S. News experts, keto ranks second-to-last — they found it hard to stick to and lacking in vital nutrients. A modified version, slightly more generous with carbohydrates, ranks at #34.

What is the keto diet?

Low-carb diets like the South Beach and Atkins diets focus on protein. But when you’re doing the keto diet, fat provides as much as 90% of your daily calories. Most plans call for keeping daily carbohydrate intake under 50 grams (for context, a medium banana has 27 grams). The goal with keto is to force your body to use fat for fuel by depriving it of its usual source, glucose — aka sugar. Without glucose available, your body enters a state known as ketosis. The ketogenic diet was originally used as a medical treatment for childhood epilepsy, but in recent years it’s become popular for weight loss.

What can you eat on the keto diet?

Think high-fat: red meat, bacon, salmon, eggs, butter and cream, cheese, nuts, healthy fats like extra-virgin olive oil, and avocados. You can also have low-carb vegetables like broccoli, celery, cucumber, and tomatoes. But since the plan restricts you to about 50 grams of carbohydrates each day, you’ll have to give up eating many grains, starchy vegetables and fruits high in sugar, any kind of added sugar, chips, and virtually all baked goods.

What are the health benefits of the keto diet?

Other than treating epilepsy, a ketogenic diet mostly aims for fast weight loss. Proponents say it can help with obesity and type 2 diabetes. But a 2019 editorial in JAMA Internal Medicine says that “enthusiasm outpaces evidence” when it comes to its effectiveness. And while some research suggests it can help control blood pressure and cholesterol in the short term, those benefits don’t seem to last after 12 months.

Who is the keto diet for?

If you’re extremely overweight or having trouble maintaining healthy blood sugar levels, a keto diet can help kick-start changes. Some research shows you’ll lose weight more quickly than on a traditional diet, and it may help your blood glucose; talk to your doctor to see if it could be a good fit for you. Another area where the keto diet shows promise but needs more research: for people with Alzheimer disease or other cognitive impairment. 

Who should not go on the keto diet?

Because the liver and kidneys do so much of the work here, anyone with existing problems might find their condition gets worse. If you have diabetes or pancreatitis, it could be risky for you, too. Even if you’re completely healthy, you should talk to a doctor or registered dietitian before you start a keto diet.

Want to explore the keto diet? Try these recipes:

Sheet Pan Pizza Chicken

We all get a hankering for pizza sometimes. When you’re avoiding carbs, that can be tricky — unless you get clever. This easy sheet pan dinner offers all the flavors of pepperoni pizza, using simply baked chicken breast as the “crust.”


Paleo diet

Americans eat too many processed foods, right? This might explain the popularity of a diet claiming to mimic what our Paleolithic ancestors ate — they didn’t have cookies, so neither should we. 

What is the Paleo diet?

In the hunt-and-gather Paleolithic era, early humans’ diet looked nothing like ours. The Paleo diet proposes that since humans stopped evolving back then, choosing food more in line with our ancestors’ diet will lead to weight loss and better health.

What can you eat on the Paleo diet?

Basically, if cavemen and women could hunt or gather it, you can eat it. Think whole foods like grass-fed meat, wild-caught seafood, fresh produce, eggs, nuts and seeds, and oils from fruits and nuts. Avoid grains, legumes, dairy, vegetable oils, refined sugar, salt, potatoes, and processed foods. This makes it a relatively high-protein diet.

What are the health benefits of the Paleo diet?

When a diet is this restrictive, it’s no surprise that it works for weight loss — it’s hard to eat a lot of calories. Studies have also shown that it may lower blood pressure and cholesterol levels, but there hasn’t been enough research to show its effects on heart health overall. 

Who is the Paleo diet for?

If you’re looking to lose weight and don’t mind cooking almost all your food from scratch (cavemen didn’t have convenience foods), this could be a good short-term choice. And since you can’t eat grains, it’s naturally gluten-free.

Who should not go on the Paleo diet?

Restricting entire food groups can be risky nutritionally and hard to sustain. It can also pose a threat to people with eating disorders. 

Want to explore the Paleo diet? Try these recipes:

Shrimp and Cauliflower “Grits”

Grits usually aren’t part of a Paleo diet, but they can be when you swap in cauliflower for corn meal. A healthy spoonful of nutritional yeast makes them “cheesy.” Cajun-spiced shrimp on top makes them a complete, satisfying meal.


Vegetarian diet

Take “meatless Mondays” seven days a week, and you’ve got a vegetarian diet.

What is a vegetarian diet?

The most basic rule of vegetarianism: Don’t eat animal flesh. From there, you have choices. The lacto-vegetarian option allows for dairy products but not eggs, ovo-vegetarians eat eggs but not dairy, and the ovo-lacto option includes both.

What can you eat on a vegetarian diet?

Depending on which type of diet you choose, you can enjoy everything but meat, fish, and poultry.

What are the health benefits of a vegetarian diet?

Looking to protect your heart as well as your kidneys? Research shows that a vegetarian diet can do both. It also lowers your risk of developing type 2 diabetes.

Who is a vegetarian diet for?

The diet offers multiple health benefits, but deciding to give up meat is largely about personal preference and concern for the environment. (Livestock accounts for 14.5% of global greenhouse gas emissions.)

Who should not go on a vegetarian diet?

This one’s easy: Meat lovers.

Want to explore a vegetarian diet? Try these recipes:

Slow Cooker Vegetable Lasagna

All the gooey, cheesy things you love about lasagna, but with no meat—and no fuss, thanks to the slow cooker. All you do is layer sauce, noodles, plenty of vegetables, and two kinds of cheese in the machine, turn it on, and go. A few hours later, you’ve got a hearty vegetarian dinner.



Vegan diet

Take vegetarianism a few steps further and you’ve got veganism.

What is a vegan diet?

A vegan diet requires giving up more than just animal flesh. You’ll have to renounce all animal products — that includes dairy and eggs as well as additives and flavorings derived from animals. Many vegans also avoid honey, which comes from bees.

What can you eat on a vegan diet?

Any food that’s 100% plant-based is fair game in veganism.

What are the health benefits of a vegan diet?

Avoiding the dietary saturated fat and cholesterol that come with animal products can have a big impact on your health. Research shows that vegans have lower BMI (body mass index) and less prevalence of diabetes than both vegetarians and meat-eaters. And plant-based diets almost halve your risk of developing metabolic syndrome, a group of chronic conditions like high blood sugar and high blood pressure, which together increase your risk of heart disease, stroke, and type 2 diabetes.

Who is a vegan diet for?

Following a strictly vegan diet requires quite a bit of effort, since so many products include animal derivatives. You might find whey or casein — both dairy products — in dark chocolate. Veggie burgers often contain eggs or dairy. Bread may have milk, eggs, butter, or derivatives. Gelatin comes from animal hooves, so that’s out. You’ll need to be dedicated, and willing to read labels.

Who should not go on a vegan diet?

Anyone who isn’t willing to do the work of sniffing out hidden animal products. And it’s relatively easy to miss vital nutrients like protein, calcium, B12, and iron. If you’re pregnant or breastfeeding, speak to your doctor and take extra care. It’s not necessarily unsafe, but you’ll need to pay close attention to your nutritional intake.

Want to explore a vegan diet? Try these recipes:

Farmers Market Vegan Breakfast Bowl

Giving up animal products doesn’t mean giving up flavor. This nutrient-packed bowl combines crunchy baked hash browns, spiced scrambled tofu, and fluffy quinoa. It’s the perfect way to start your day — or an excellent breakfast-for-dinner.


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