The Diets that Really Work (and a Few That Don’t)

Should you try Paleo or Atkins, Whole30 or maybe even go vegan to lose weight? The expertsí answers may surprise you.

By Paula Derrow

On paper, losing weight looks like an easy proposition—eat less, exercise more, and voilà, you’re back into your skinny jeans before you know it. But there’s a reason the diet industry raked in more than $66 billion last year, and it’s this: most diets, however popular, are hard to keep up—and falling off the wagon can lead to even more weight gain. That’s why many experts believe you shouldn’t consider your weight-loss efforts a “diet” at all, but a way of eating.

“It’s better to think of foods you can add to your plate, rather than what you’re taking away,” says Angela Lemond, a registered dietitian, nutritionist, and co-owner of Lemond Nutrition.

So where does that leave the women who say they want to lose weight? One-third of Americans are obese. If you want to take off pounds, “the best diet is the one that you’ll be able to stick with,” says Rekha Kumar, MD, an endocrinologist and medical director of the Board of Obesity Medicine at New York-Presbyterian/Weill-Cornell Medicine in New York City.

In a 2014 study in the Journal of the American Medical Association that compared a number of popular diets, including low carb and low fat, the researchers found very few differences in weight loss among various plans. The right diet is “any diet that a patient will adhere to in order to lose weight,” the authors concluded. With that in mind, Dr. Kumar and Angela Lemond evaluate six popular diet plans in terms of stick-to-itiveness and overall healthfulness.

Paleo Diet and Whole30
HOW THEY WORK: The Paleo diet is meant to mimic the way people ate in “caveman” times—basically, it eliminates grains, legumes, dairy, processed foods, refined sugar, vegetable oils, and salt. That leaves so-called basic foods that hunter-gatherers might have been able to get their hands on, including fresh fruits and vegetables; grass-fed meat; seafood; eggs; nuts and seeds; and healthful oils.

Whole30 takes the restrictions one step further, eliminating sugars including even naturally occurring sugars such as honey and maple syrup.

WHAT THE EXPERTS LIKE: If you’re looking for a way to lose weight quickly—to fit into a dress for an upcoming wedding, for instance—you’ll likely drop pounds if you stick with either of these plans, agree Dr. Kumar and Lemond. Paleo and Whole30 may also be good options for people with diabetes, due to the low-carb factor, which can lower blood sugar. “I’m a big fan of eating foods in their whole form, as opposed to consuming processed foods,” says Lemond.

WHAT THEY LIKE LESS: Both diets are so rigid that most people can’t stick with them for more than a few weeks at a time. “They’re definitely not doable for life,” says Lemond. “Whole30 isn’t even intended to be a weight-loss diet, but more of a 30-day cleanse for people suffering from gastrointestinal issues, skin problems, and other things that may be diet related,” she explains. “The point is to eliminate possible dietary triggers for these issues. The problem with eliminating entire food groups is that there are almost always unintended consequences—it’s tough to get enough calcium and vitamin D if you don’t do any dairy, for instance.” Dr. Kumar agrees: “Skipping dairy isn’t good for your bones. Most cavemen didn’t live until their 70s, 80s, or 90s, so they didn’t experience the effects of osteoporosis.”

IF YOU DECIDE TO TRY THEM: “Give yourself some leeway,” recommends Lemond. “Allow yourself some foods off the plan to start, and maybe even ongoing. That makes the plan much more sustainable.” But unless you really, really love fruits and vegetables, you’ll likely end up falling short on nutrients—and falling off the wagon.

Very low fat such as TLC Diet and Pritikin
HOW THEY WORK: Very low-fat diets, including the TLC (Therapeutic Lifestyle Changes, developed by the National Institutes of Health) and the more restrictive Pritikin, were all the rage in the 1990s, when scientists pointed to dietary fat as the root cause of heart disease. These plans favor fruits, vegetables, whole grains, starchy vegetables, legumes, low-fat dairy, fish, poultry, and lean red meat.

WHAT THE EXPERTS LIKE ABOUT THEM: There’s a lot of data showing that a diet low in saturated fat can reduce both cholesterol and the risk of heart disease. “When it comes to your health, restricting saturated fat is the behavior we have the most evidence for,” says Dr. Kumar.

WHAT THEY LIKE LESS: “It’s tough to feel full on a diet of all carbs, which leaves you vulnerable to bingeing behavior and weight gain—reversing the heart-healthy benefits of cutting out saturated fat in the first place, according to Dr. Kumar. “You can’t just say that fat is bad,” she says. “There are good fats and bad fats, and good cholesterol and bad cholesterol.” Dr. Kumar prefers the more moderate TLC diet to Pritikin. “TLC distinguishes between which kinds of fats are healthy—avocado, olive oil, and certain nuts can help raise your good HDL cholesterol. It’s the saturated fats in full-fat dairy and fried foods you want to stay away from.” Adds Lemond: “When you go very low in fat, it’s easy to overdo the carbs, or eat the wrong kind of carbs. You have to make sure you are going with whole grains and staying away from refined sugar.”

IF YOU DECIDE TO TRY THEM: Go with TLC as opposed to more rigid regimens. “TLC is really great if you want to lower your cholesterol,” Lemond underscores. “It emphasizes foods that are naturally going to pull cholesterol out of your diet, including legumes, and foods that are high in soluble fiber, like lima beans and oatmeal. You can drop your cholesterol a good 10 points or more.”

Mediterranean and DASH
HOW THEY WORK: The Mediterranean diet and its more Americanized cousin, the DASH (Dietary Approaches to Stop Hypertension) diet, are based on the Mediterranean way of cooking and eating—that is, plenty of fruits and vegetables; whole grains; legumes; nuts and seeds; low-fat or nonfat dairy products; healthy fats like olive oil and avocado; fish and poultry twice a week; red meat no more than a few times a month. The DASH diet tends to be lower in sodium than the Mediterranean; the Mediterranean is lower in dairy and more generous with healthy vegetable oils. Both plans have been shown in randomized trials to reduce the risk of heart disease—the number one killer of women—as well as diabetes, stroke, and certain cancers.

WHAT THE EXPERTS LIKE: These diets aren’t restrictive, which means you can keep them up over the long haul. Plus, you can drink wine! “I’m a big fan,” says Lemond. “Because you are eating more fruits and vegetables, the higher-fat foods, like meat, naturally get squeezed off the plate.”

WHAT THEY LIKE LESS: Weight loss isn’t always fast and furious. You don’t get the dramatic, quick drop in pounds that you might experience with more restrictive plans—“though if you follow the diet, you will likely lose weight,” says Dr. Kumar. “It’s healthier than the way most Americans eat.”

IF YOU DECIDE TO TRY THEM: Dr. Kumar recommends doing these diets with extra calorie restriction if your main goal is weight loss—for women, she says, trying “to keep your calories to 1,400 a day.” (Calorie-counting apps like MyFitness Pal and Lose It! can help you keep track.)

HOW THEY WORK: A vegan diet is completely devoid of animal products, both the obvious ones (meat, fish) and the less obvious (dairy, eggs, even honey). Everything else is on the table, including plant-based foods and vegan versions of sweets (yes, there are vegan Oreos) and even Bacon bits.

WHAT THE EXPERTS LIKE: “For the most part, a vegan diet emphasizes power foods that are high in nutritional value and low in calories,” says Lemond. “Everyone benefits from that.” Most people lose weight on a vegan diet. Veganism is also environmentally friendly, leaving a smaller carbon footprint than other ways of eating.

WHAT THEY LIKE LESS: If you don’t absolutely love fruits and vegetables, veganism will definitely feel too punishing. “While cutting animal products out of your diet reduces your risk of certain diseases, it could also put you at risk for developing a vitamin B12 deficiency,” says Dr. Kumar. “And when you cut several food groups out of your diet completely, it’s likely that you’ll overdo another group—like carbs.” It’s also easy to overeat vegan desserts and snacks that aren’t necessarily low calorie. “I’ve definitely seen overweight vegans,” says Lemond.

IF YOU DECIDE TO TRY THEM: “I recommend that people get some guidance from a nutritionist, to make sure you’re not missing out on important nutrients, like B12,” says Lemond. Adds Dr. Kumar: “Considering how varied our diets need to be to get all the requisite micro- and macronutrients, you really have to pay attention to what you’re eating to make sure your body isn’t missing out.

Very low carb such as Keto and Atkins
HOW THEY WORK Low-carb diets put the kibosh on carbohydrates—not just grains but also most fruits and starchy vegetables. That leaves meat, poultry, fish, and eggs, though some low-carb plans allow limited fruits and nonstarchy vegetables. While the typical American diet comprises 45 to 65 percent carbohydrates, the keto diet reduces that percentage to as low as 5 percent of daily food intake, and Atkins to 10 to 20 percent, to lower blood sugar and insulin levels. “Eating a meal high in simple and refined carbs can spike insulin, leading to more rapid hunger, whereas a meal higher in protein leaves you satisfied for longer,” Dr. Kumar explains.

WHAT THE EXPERTS LIKE ABOUT THEM: A low-carb plan can help you drop weight fairly quickly, and can lower risk factors associated with diabetes, including high blood sugar and blood pressure. “Most of us are eating way too many carbs,” says Lemond.

WHAT THEY LIKE LESS: Besides being too high in saturated fats, the most extreme low- and no-carb diets can cause uncomfortable symptoms, including constipation, headaches, and electrolyte problems. Plus, a diet without carbs of any kind is tough to stick to. “While a low-carb plan is an effective way to lose weight, you have to be careful,” says Lemond. “Take it too far and you may begin craving sweets at night.”

IF YOU DECIDE TO TRY THEM: Take a more moderate approach to low-carb eating—specifically, with a plan that gives the green light to complex carbs such as whole grains, steel-cut oats, and sweet potatoes, as well as fruits that don’t spike blood sugar excessively, like berries and melon. “Carbs are an essential part of a healthy diet and a good source of B vitamins and folic acid,” says Lemond. “They shouldn’t be vilified.”

Intermittent fasting
HOW THEY WORK: Instead of focusing on what you can eat (and can’t) every day, intermittent fasting involves drastically restricting calories (often to under 500 calories a day) for relatively short periods. Some programs call for dramatic calorie reduction two days a week; others suggest going 16 hours without food, say, by eating an early dinner and then a very late breakfast; still others call for total fasting for 24 hours twice a week. You get the idea. “The strategy has shown some promising results, not just for weight loss and reducing insulin levels, but also for decreasing the incidence of certain cancers,” says Lemond. “The premise is that when your body doesn’t have to digest food at night, it can focus on doing other things, like cell repair.”

WHAT THE EXPERTS LIKE: “Many of my patients tell me that skipping meals for one or two days is easier than counting calories—that they can do anything for two days a week,” says Dr. Kumar. It can also be a good way to jump-start weight loss if you’re struggling to break through a diet plateau.

WHAT THEY LIKE LESS: It’s easy to make up for a day of fasting by overdoing it for the next two days. “Most people have a hard time doing a total fast without compensating for it,” says Lemond.

IF YOU DECIDE TO TRY THEM: “Start with a more moderate type of fast, like not eating after 7 pm at night, then postponing breakfast until 8 or 9 am the next day,” says Lemond. DW

Paula Derrow is a writer and editor in New York City specializing in health, psychology and the personal essay. She has written widely for national publications. Find out more about her at

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