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How to Lose Weight Now

What to Steal From Keto, Paleo and Other Trendy Diets

Experts sort through the fads to see what really helps you lose weight

Close up of steak, vegetables and a baked potato on a platter.

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En español | With your best friend raving about paleo and your daughter eating raw foods, you might be feeling like a slouch for not jumping on the latest diet trend yourself.

But you shouldn't. Rigid regimes and complete diet overhauls can be especially tough to stick to, says Kristen Smith, a dietitian and spokesperson for the Academy of Nutrition and Dietetics. She says weight loss success comes from focusing on “lifestyle changes that work for you and you can maintain for the long haul.”

That doesn't mean there isn't anything of value in most popular diets. Even if you aren't about to go full-throttle keto, our experts say you can find some valuable à la carte wisdom on the following five weight loss plans. What follows are the helpful takeaways from each.

Keto

The first high-fat, very-low-carb diet regimen was developed more than a century ago to treat medical conditions such as epilepsy. While there are several variations on today's keto, generally, a heaping 70 to 80 percent of your daily calories will come from fat, 10 to 20 percent from protein, and a scant 5 to 10 percent from carbs. On the keto menu: meats, dairy, nuts, avocados, cheese, fish, poultry and non-starchy vegetables like broccoli and leafy greens. You avoid bread, cereals, pasta, legumes and most fruits. (Fats are valued so much that some keto followers even swirl butter into their morning coffee.)

Any diet that stars bacon would seem a dubious road to weight loss. But there is solid science behind it. If you deprive the body of carbs to make glucose, it starts burning your stored fat as its energy source, a process called ketosis. (You can't have “cheat days” or you will stop this process.) Fat is also very filling: Eating keto can suppress your appetite and reduce cravings so you may take in fewer calories, says Samantha Cassetty, a registered dietitian in New York City and coauthor of  Sugar Shock

Does it work? Some research has found that going keto can help you drop pounds if you can stick with it. A 2020 study in the journal Nutrition & Metabolism, for example, found that participants (34 men and women ages 60 to 75) in an eight-week trial lost an average of nearly 15 pounds. There's not yet a lot of research into keto's longer-term benefits for weight loss, however.

The downside: Leaving out fruit and whole grains can result in constipation and nutrient deficiencies, so supplementation might be necessary. Eating this way can be hard to sustain — when you go back to eating your ordinary crackers and pasta, you may gain the weight back. And consuming too much meat may increase your cholesterol levels over time. “We don't know the cardiac consequences of following this diet long term,” says Smith. In the short term, you may suffer “keto flu” symptoms such as nausea, fatigue and headaches as your body adjusts.

What to steal: Fat is not the enemy. The low-fat diet craze that started in the ‘80s may have scared dieters away from all fats. But not all fats are bad fats. “Eating moderate portions of healthy fats can help you lose weight. Unsaturated fats like olives, nuts, seeds and olive oil can help reduce appetite and promote a feeling of fullness,” says Cassetty, adding that these foods also add flavor or texture that improves the appeal of the nutritious foods like veggies they're often paired with.

Paleo

Also known as the Stone Age diet, this approach asks you to eat like a supposed long-ago hunter-gatherer ancestor: If it wasn't served up around the cave fire after a long day of fishing, hunting or foraging, it's off limits. You eat fish, meat, fruits, vegetables, nuts and seeds, and avoid processed foods, grains, dairy and legumes, and added sugar and salt. Proponents say that our bodies evolved to eat only foods available to early humans and that sticking to those can help fend off such modern-day scourges as heart disease, diabetes and cancer while helping you lose weight.

Does it work? Small short-term studies have shown that paleo can help you drop pounds and reduce your waist circumference. Like keto, the long-term weight loss benefits require more research, Smith says.


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The downside: This diet excludes beans, chickpeas and other legumes because they are cultivated rather than foraged. “But this category is full of nutrients like magnesium and folate, and are some of the healthiest foods on the planet,” Cassetty says. Plus, in the modern world, it may be difficult to stick with the diet's restrictions.

What to steal: Eat real foods. The standard American diet today is filled with ultra-processed foods and processed ingredients our forebears wouldn't recognize. Limiting these categories as paleo does is a smart idea. Filling up on those caveperson faves — high-fiber, low-cal fruits and vegetables — can help keep pounds off.

16/8 intermittent fasting

With the 16/8 diet, you eat all your daily calories during an eight-hour window, then abstain completely the other 16. You might finish dinner by 8 p.m., say, then fast until lunch the next day. (Noncaloric beverages like coffee and water are OK.) By limiting the amount of time you eat every day, you may naturally take in fewer daily calories, Smith says. Fasting can kick your body into burning stored fat and provide other metabolic benefits that may boost longevity.

Does it work? To date, most of the research into fasting for weight loss has been done with animals. In humans, the evidence is mixed: One 2018 study published in the journal Nutrition and Healthy Aging found following a 16/8 regimen for three months decreased body weight by about 3 percent. But a 2020 human study in JAMA Internal Medicine showed little weight loss benefit: Overweight adults assigned to fast for 16 hours a day for three months lost only two or three pounds — much of it healthy muscle mass, not body fat.

The downsides: Not eating for long periods takes lots of willpower and can be hard to stick with over the long haul. “Fasting can foster an unhealthy attitude toward food. You are not learning to listen to your natural hunger cues, which is important for maintaining a healthy relationship with food,” Smith says. Fasting is not safe for people with prediabetes, diabetes or a history of disordered eating, she adds.

What to steal: Don't nosh around the clock. Deciding the kitchen is closed after dinner can prevent mindless midnight munching. “Giving yourself a natural 12-hour break allows your body to get into healing and maintenance mode while you sleep instead of putting energy into digesting,” Cassetty says.

Whole30

Whole30 is a one-month dietary reboot. For 30 days, you eat only a limited menu of whole foods — meat, seafood, eggs, fruit and veggies, and natural fats like olive oil, nuts and seeds. You can't have added sugars, artificial sweeteners, alcohol, grains, legumes, dairy or junk foods, which, the thinking goes, may be triggering inflammation and allergies. This cold-turkey approach is designed to help you break your cravings and bad food habits, and begin with a clean slate. In the process, you may lose some pounds as well. After the 30 days, you slowly reintroduce the excluded foods to your diet and see how each makes you feel.

Does it work? Personal testimonials abound on Instagram and elsewhere. “But I don't know of any scientific research behind this diet. It wasn't created by a credentialed expert,” Cassetty says.

The downsides: “It is very restrictive,” says Amy Gorin, a registered dietitian in the New York City area and owner of Plant-Based Eats. “If you slip up and eat a bite of pizza, you have to start over. This type of unforgiving mentality doesn't work well with making lasting lifestyle changes.” You may risk nutritional deficiencies if you follow it longer than a month: “I don't recommend doing so,” Gorin says.

What to steal: Be more mindful. Though this scorched-earth approach may be extreme, experts say it can be useful to experiment with cutting back on potentially problematic categories like refined sugar or alcohol consumption. Do you sleep better or have more energy? “It can be helpful to examine eating habits you do mindlessly,” Cassetty says.

Weight Loss — in a Pill?

Coming soon: More safe, effective weight loss medications

It's no secret: The average American is getting bigger. Some 42 percent of adults now meet the definition of obesity, with a body mass index of 30 or above. Guilt and willpower haven't worked to solve this epidemic. “Obesity is a complex process,” says Marcio Griebeler, M.D., director of the Obesity and Medical Weight Loss Center at Cleveland Clinic's Endocrinology and Metabolism Institute. “We need to view it as a chronic disease and treat it as such.” One promising approach? Better, safer weight loss medications.

A few prescription medications already are approved by the Food and Drug Administration (FDA) for weight loss, including Qsymia and Contrave. Doctors prescribe them for those whose health is at the greatest risk because of their weight: those with a BMI over 30, or over 27 if they have other health issues such as high blood pressure. (You won't get an Rx if you just want to lose five pounds for your reunion.) These medications work on the “brain-gut connection,” Griebeler says. They reduce your appetite, quell cravings, or slow digestion so you feel fuller longer. “Along with lifestyle changes, they can be effective at jump-starting weight loss.”

Unlike earlier diet drugs that proved dangerous, such as fen-phen (fenfluramine and phentermine), these medications have been found to be generally safe in the long term under medical supervision. But results are “very individual,” Griebeler notes. Patients typically lose around 5 percent of their body weight after three months, which can be enough to make a significant difference in health.

Just released this year is a new prescription product named Plenity, a pill filled with cellulose and citric acid. The FDA has labeled it a “device” rather than a medication because it passes through your digestive system without being absorbed in your bloodstream. You take it before eating and the contents expand. “Your stomach has less space for food, so you eat less,” Griebeler explains.

Griebeler says he's “very optimistic” about the potential for several other promising medications expected to hit the market in the next five years. “Some of these are combinations of existing drugs, others are based on diabetes drugs,” he says. You can't get an Rx yet, but you can find an obesity specialist who will be knowledgeable about all treatment options as they arrive.

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