For people looking to lose weight or reach another specific health goal, there are an overwhelming number of diets to consider. We asked experts to explain fad diets, including the pros and cons of each. Some fad diets are unsustainable or simply ineffective for most people, but other diets—like the Mediterranean diet—become popular because there’s evidence that they really do help people reach their health goals.
How can you tell the difference between a fad diet and one that’s buzzy because it works? “A fad diet promises speed, while sustainable nutrition promises consistency. That’s the difference,” explains Kylie King, M.S., R.D., a registered dietitian and founder of Kylie King Nutrition.
Meet the experts: Kylie King, M.S., R.D., a registered dietitian and founder of Kylie King Nutrition; Jessica Cording, M.S., R.D., is the author of The Little Book of Game-Changers: 50 Healthy Habits For Managing Stress & Anxiety; Keri Gans, R.D., is the author of The Small Change Diet; nutritionist Sonya Angelone, R.D.
If you’re wondering about a trendy diet that’s come across your Instagram or TikTok feed, here’s what to pay attention to: “If a diet tells you exactly how much you’ll lose by exactly when, walk away. Nobody can predict how fast any one person will lose weight,” says King. “Watch for the villain. Fad diets always seem to need one. Carbs, gluten, fruit, dairy, raw vegetables, cooked vegetables. If a plan blames one food for everything, it’s marketing, not science.”
Below, experts explain the pros and cons of several popular diets.
Macrobiotic diet
The macrobiotic diet encourages followers to focus on eating whole foods over processed foods, explains Jessica Cording, M.S., R.D., author of The Little Book of Game-Changers: 50 Healthy Habits For Managing Stress & Anxiety. It also encourages followers to lead a slower lifestyle and to be mindful about eating. The diet is rigid, with meals that focus on having whole grains, fruits, and vegetables. It also focuses on avoiding foods that contain “toxins,” Cording says.
Pros:
The macrobiotic diet “includes a variety of whole, minimally processed foods,” says nutritionist Sonya Angelone, R.D. She also likes that the eating plan “encourages positive eating behaviors like mindfulness when eating.”
Cons:
“There is potential with this diet, but it can be very restrictive,” Cording says. She points out that followers are encouraged to avoid nightshade vegetables, like potatoes, peppers, and tomatoes. “While some people might feel better without those, not everyone needs to avoid nightshades,” Cording says. “This can cause people to narrow their food options down too much.” The macrobiotic diet can also be low in certain key nutrients like vitamin B12, calcium, and iron, Angelone says.
Noom
Noom is an app-based plan that’s designed to teach followers how to make smart, sustainable choices around food, Cording explains. Noom has “health coaches” if you use a paid subscription to the app who can provide feedback. Foods are color-coded to be green, yellow, and red to signal how many calories they have. Noom also asks you to count calories and weigh yourself daily.
Pros:
“Noom has an emphasis on changing behaviors to promote long-term weight loss success,” Angelone says. “There are personalized diets and support available.”
Cons:
To access all the features of Noom, you have to pay up to $59 a month. “The cost may be prohibitive for some,” Angelone says. Noom’s health coaches also aren’t registered dietitians and the plan can sometimes recommend very restrictive calorie counts, Cording says.
South Beach
The South Beach diet was created by cardiologist Arthur Agatston, M.D., originally as a way to help patients with conditions like heart disease and type 2 diabetes, Cording says. South Beach encourages followers to focus on lean proteins, low-fat dairy, whole grains, vegetables, and fruit. It follows different phases, including an original restrictive phase that’s designed to get rid of cravings for sugars and starches, a second phase where you add back in some whole grain breads, fruits, and vegetables, and a third maintenance phase, Cording says.
Pros:
“After the beginning phases, it encourages well-balanced eating that includes plenty of fruits, veggies, and 100% whole grains, plus daily exercise,” says Keri Gans, R.D., author of The Small Change Diet. “This diet provides good variety in a structured approach,” Angelone says. “This allows users to gradually learn to adopt better eating habits.” She also likes the balance of proteins, complex carbs, and healthy fats.
Cons:
The initial phases are “pretty restrictive,” and that can be difficult for some people, Angelone says. “It is lower in carbs initially so it may be accompanied by fatigue or headaches,” she says. “Planning is required so it may not be very convenient for some.”
Weight Watchers
Weight Watchers uses a points system to help followers learn to eat healthy and in moderation, while focusing on foods they enjoy. The company also provides virtual support meetings for followers.
Pros:
“It’s very much about prioritizing what indulgences are worth it to you,” Cording says. “It gets people to think about portion sizes and how to “budget” —when to indulge—which is an element of mindfulness that I appreciate.” The points system also allows for flexibility with foods, Angelone says. “The track record of success is better than for most other programs,” she says. “The support system of in-person or online meetings helps build a community for support.”
Cons:
Some of the foods in the points system are controversial with dietitians. “Some nutrient-dense foods are given a higher points value and people miss out on them because of the higher points,” Cording says. “Some people also tell me that they get tired of counting points.” When people stop the program, they often gain the weight back, Gans says.
This eating plan is a consistent favorite of dietitians. It focuses on heart-healthy foods enjoyed by people in the Mediterranean region, like fish, nuts and legumes, vegetables, and fruits. It even makes room for red wine in moderation, Cording says.
Pros:
Angelone calls the Mediterranean diet a “healthy diet for life” that people can maintain after they lose weight. “It includes a wide variety of food choices, including healthy fats and seafood but limited sodium, saturated fats, and refined carbs,” Angelone says. “It is also a good choice if you have other health conditions like diabetes, heart issues, joint or bone health concerns.” Angelone points out that it’s easy to follow and family-friendly, too.
Cons:
The Mediterranean diet doesn’t include overly processed and fast foods, which can make it hard for people who don’t have time to cook or plan meals, Angelone says. Still, “the only difficulty could be for those individuals who really need a solid plan with stricter guidelines to follow,” Gans says.
Zone
The Zone diet is big on balancing carbs, protein, and fat. Users follow a 30-30-40 breakdown of macronutrients, aiming to get 30% of their calories from protein, 30% from fat, and 40% from carbohydrates, Cording says. Followers are also encouraged to eat within an hour of waking up and to have a snack before bed, Cording says.
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Pros:
Cording gives the Zone the thumbs up for emphasizing blood sugar balance. “It emphasizes eating consistently throughout the day and I think that’s positive,” she says. “No foods are totally off-limits.” Angelone also likes that the diet focuses on minimally-processed foods.
Cons:
Eating within an hour of getting up and having a snack before bed isn’t a good fit for everyone, Cording says. Others can find it tough to stick with the 30-30-40 rule, she says. “I’ve had people tell me that they don’t like feeling like they can’t even have a snack without thinking about the ratio,” she says.
Atkins diet
The Atkins diet has changed over time to be a little healthier than its bacon- and steak-heavy original version. The eating plan focuses on balancing lean proteins, fat, and healthy carbs, Cording says. Atkins recommends that followers minimize refined flour and sugar, although it also restricts whole grain foods until you reach the maintenance phase. Adkins is one of the original low-carb diets, Gans says. “Its four-phase program can be extremely restrictive at the beginning, especially with phase one allowing less than 20 grams of carbs per day, she says.
Pros:
“Weight loss is fast in the initial phases with little hunger due to the high fat and protein content of the diet,” Angelone says, noting that it “may help with blood sugar problems.”
Cons:
“By phase four, the diet becomes much more inclusive of carbs; however, too many people never leave phase one, making the diet too difficult to follow,” Gans says. The low-carb diet may also cause people to have fatigue, keto breath, or sluggishness while their body adapts to the plan, Angelone says. “It may also lead to nutrient deficiencies due to food restrictions,” she says, noting that “the low fiber diet may even lead to constipation.”
Volumetrics
Volumetrics focuses on the quantity of foods you eat, as well as nutrient-dense foods. The goal is to have you fill up on high-fiber foods like fruits and vegetables and have you eat based on how full you feel, Cording says. Volumetrics includes regular meals and snacks, Angelone says.
Pros:
“It really helps people learn about portion sizes and the benefit of adding fiber-rich foods to add volume and help you feel fuller on less food and fewer calories,” Angelone says, noting that the diet includes “plenty” of fruits and vegetables. “High water foods tend to promote satiety and less hunger for the calories,” Angelone adds.
Cons:
Volumetrics requires food planning to make sure followers have enough nutrient-dense foods, Angelone says. It’s also not a structured, formal weight loss plan, which some may struggle with, she says.
The raw food diet tells followers to focus on foods that are cooked no more than 118 degrees Fahrenheit, Cording says. The idea behind this is that cooking food will break down enzymes and get rid of nutritional benefits, she explains.
Pros:
Angelone likes that this is a high-fiber diet that can help promote good bowel movements and health. “It focuses on raw fruits and vegetables, which are nutrient-dense,” she adds.
Cons:
This diet tends to be lower in protein and calcium, Cording says. “It’s also very restrictive,” she adds, noting that cooking can actually enhance the absorption of certain ingredients. “This is not something that I encourage someone who is looking for a sustainable approach to healthy eating to follow,” Cording says. Cording also flags that the high-fiber diet may cause people to have gas and stomach pains.
Nutrisystem
Nutrisystem focuses on premade meals you just heat and eat. The meals are created based on your age and gender, and many followers find that it’s a convenient way to eat a lower-calorie diet without having to track macros or count calories, Cording says.
Pros:
“Prepackaged meals makes this a no brainer—it’s easy to follow,” Angelone says. The meals also often have a certain protein, carbohydrate, and fat count, Cording says, adding, “I’ve found that people like that.”
Cons:
All of those meals can be costly. “It’s also processed, packaged food,” Cording says. She also says this isn’t a sustainable eating plan. “You may lose weight on Nutrisystem, but when you go off it, you may gain it back because you didn’t learn how to control calories yourself,” she says. It’s also hard to follow Nutrisystem in social situations, Angelone says.
Paleo
The Paleo diet “promotes eating like hunters and gatherers,” Gans says. It has a strong emphasis on whole fruits and vegetables, nuts and seeds, and lean proteins. Paleo also encourages its followers to exercise regularly, Cording says.
Pros:
Angelone likes the emphasis on whole foods, with minimal overly processed and refined foods. “For people with some sensitivities, whether autoimmune conditions, wheat, or rye sensitivities, I have seen Paleo work for some people,” Cording says.
Cons:
Gans says Paleo is a little confusing. “While its premise is to consume only foods that were around during the Paleolithic era, it won’t dismiss a coffee run to Starbucks,” she says. The diet also eliminates grains and dairy, which can cause people to feel low-energy, Angelone says. “It also may be hard to follow for a vegetarian since it isn’t really plant-based,” she says.
How to choose the right diet for you
Your healthcare provider may be able to help you decide which eating habits might help you reach your health goals, whether you’re looking to lose weight, lower your blood pressure, or manage a chronic health condition. King says there are a few questions to ask yourself before trying any diet, especially those you see on social media:
- Who is telling me this and what are they selling? “Check the credentials. ‘Wellness coach’ is not a credential. RD or RDN means a degree in nutrition science, a supervised internship, and a board exam,” says King.
- Could I eat this way for a year? For five years? “If the answer is no, it is not a sustainable approach to eating but rather an extreme alternative to your real eating habits,” she says. “And once the diet is over, you’re likely to return to them.”
- Does it cut foods I actually like? “A plan that bans your favorite foods works until the next birthday party. And then it doesn’t,” she says. “If it keeps you in an on-again, off-again cycle, then it isn’t the right fit.”
- Do I have a condition this could affect? Some of the examples King mentions are diabetes, kidney disease, high cholesterol, or a history of disordered eating. “In these cases, a trending fad diet is not a small risk,” she says.
