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Weight loss continues to be the top reason for changing diets, but gone are the days when getting skinny was the overriding goal. Losing weight in a healthy, sustainable way is today’s holy grail.
Successful diets favor or restrict different types of foods, but they have some common threads. Processed food is out. Fresh food is in. Carbs need some control. And wholesome, high-quality fuel is essential.
Counting calories and measuring portions aren’t top concerns these days. Most modern eating plans focus on choosing foods that are nutritious and satiating and that enhance metabolic health, which helps control appetite and reduce cravings. Here’s a look at some of the best:
An analysis of American diets over an 18-year period by Harvard and Tufts universities in Boston found that an average of 42 percent of our calories come from low-quality carbs: refined grains, starchy vegetables (think fries), and foods and drinks with added sugars. Low in nutrients but high in calories, these foods contribute to diabetes, heart disease, and some cancers, as well as weight gain.
So instead of limiting calories by cutting back on fats, reducing carbs can produce weight loss that’s more realistic to maintain. When people lose weight on low-fat, high-carb eating plans, they usually experience a significant drop in metabolic rate—often referred to as a “slowed metabolism.” As they shed more pounds, their bodies burn fewer calories until it becomes unrealistic to keep calories low enough to prevent weight regain.
Studies that have tested the effects of different diets on metabolism show that low-carb diets avoid this slowed-metabolism dilemma. Compared to a low-fat, high-carb weight-loss diet, one that is low in carbs can increase the number of calories burned by about 90 to more than 400 calories daily, depending on the level of carb restriction.
There isn’t one single definitive low-carb diet, but cutting down on carbs—especially refined, starchy, and sugary foods and drinks that are low in nutrients—is a common feature of many healthy and effective diets. You can start by making simple substitutions such as nonstarchy vegetables for grains (including corn), mashed or riced cauliflower for potatoes, and unsweetened or stevia-sweetened drinks for those with added sugar.
The lowest-carb diet of all, the keto diet replaces most carbs with fat and alters the way the body produces energy. Instead of carbs being used to produce blood sugar—the body’s usual fuel—the lack of dietary carbs forces the body to use fat for fuel.
The body doesn’t burn fat directly. Rather, it converts it to ketones, chemicals that can then be used for energy. Once this mechanism is turned on, it’s easier for body fat to be used as fuel.
Rapid initial weight loss—as much as 10 pounds in 2 weeks—is partially water loss, as the keto diet has a diuretic effect. Fat loss follows, while preserving metabolic rate and muscle. Switching to fat burning can also reduce blood pressure and risk for diabetes and can help to reverse the disease.
Related: Keto Diet for Beginners
Because keto diets reduce cravings and appetite, people following them tend to eat fewer calories. However, weight loss isn’t guaranteed because it is possible to overeat on a keto diet. In fact, when keto diets are used to treat epilepsy and other neurological diseases—conditions where weight loss may not be a desirable goal—the diet is usually designed to preserve body weight.
In addition to the potential for overeating, another drawback of the keto diet is that it can be difficult to follow because it contains as little as one-tenth the usual amount of carbs. The daily carb content of the average American diet ranges from 200–350 grams, or about 55 percent of total calories, whereas a keto diet contains 5–10 percent carbs, typically about 20–50 grams daily.
Decades of studies of the Mediterranean diet show that it has a therapeutic effect on the heart, overall health, and longevity. And it also has weight-loss chops.
Canadian researchers compared the results of different diets on a total of 998 people over a period of a year or more. They found that a Mediterranean diet was more effective than a low-fat diet in terms of weight loss, and just as effective as a low-carb approach.
But the benefits may go beyond just losing weight. An 18-month study in Israel compared a low-carb Mediterranean diet with a low-fat diet in 80 people with abdominal fat. Both diets contained comparable calories and produced similar weight loss but differed in another way. Body scans showed that the Mediterranean diet produced twice as much loss of fat around the heart—the most harmful fat that raises risk for heart disease—and a loss of nearly 3 inches around the waist. The low-fat diet produced a loss of only 1 inch around the waist.
The Mediterranean diet contains lots of fresh vegetables, some fish and poultry, very little red meat, extra virgin olive oil, herbs and spices, and some fruit, nuts, seeds, legumes, eggs, dairy, and grains. A low-carb Mediterranean diet would contain only small amounts of legumes, grains, and starchy vegetables.
A vegan diet consisting of fresh vegetables, grains, legumes, nuts, seeds, and healthy fats from plants can improve overall health and lead to weight loss. Wholesome vegan diets are generally high in nutrients, and—because of their fiber content—satiating.
Studies have shown that a healthy vegan diet enhances the balance of gut bacteria, reduces chronic inflammation, and improves markers in type 2 diabetics. For weight loss, a vegan diet with 30 percent protein from plant foods was as satisfying as a meat-based diet.
A study at the George Washington University School of Medicine in Washington, D.C., compared a traditional heart-healthy diet with a low-fat vegan diet among 64 overweight postmenopausal women. During a period of 14 weeks, women on the vegan diet lost more weight than those on the traditional diet.
Although not as widely studied as some other diets, the paleo diet has been shown to improve markers of heart health and risk for diabetes, as well as helping with weight loss. Studies have shown that compared to a more traditional reduced-calorie diet that includes all food groups, a paleo diet can produce more weight loss and can be more satiating. However, it can be difficult to follow.
Based on the premise that our bodies are designed to eat like our hunter-gatherer ancestors, the paleo diet excludes all grains, added sugars, refined oils, dairy products, legumes, and white potatoes. It does include all other vegetables, fruits, lean meats, fish and seafood, eggs, nuts, seeds, small amounts of honey, and unrefined fats such as olive oil and coconut oil. Starchy root vegetables should be eaten only in small quantities.
Created by Mark Hyman, MD, an integrative physician and pioneer of healing diets, the “pegan” diet is a combination of paleo and vegan. It aims to combine the benefits of both those popular eating plans.
About 75 percent of the food in a pegan diet comes from vegetables and some low-sugar fruits such as berries. The other 25 percent allows protein from pasture-raised animals and healthy fats in nuts, seeds, and omega-3s from low- mercury fish such as wild salmon and sardines. Avocado, extra virgin olive, and coconut oils, are also included.
Grains, beans, dairy, and added sugars are discouraged, but may be eaten occasionally. Food additives and refined oils are excluded. Overall, the pegan diet isn’t as restrictive as paleo or vegan diets and is easier to follow.
In this type of eating regimen, there is no restriction on types of food, only timing. Although this approach may not work for everyone, there is evidence that it can be an effective weight-loss approach with greater improvement in blood sugar than diets that restrict food every day.
Fasting one or two days each week is one way of doing this. Another is eating all your day’s food within an 8-hour window, such as between 10 am and 6 pm, leaving a 16-hour break between meals.
Related: Understanding Trending Diets
The 5:2 diet is another option: on two nonconsecutive days each week, eat only 500 calories if you’re a woman, or 600 calories if you’re a man, and then eat normally the other five days of the week. In addition to weight loss, this approach can reduce risk for diabetes.
did you know … Although there are many choices when it comes to losing weight, the best diet is the one you can follow and adapt to your life.
Combining Weight-Loss Strategies
Limiting carbs, or at least starchy and sugary carbs, works well in any type of diet, and different diets may work better at different times. One study found that people lost 10 percent of their starting weight and kept it off by following a keto diet for 20 days, then switching to a Mediterranean diet for 4 months, then switching back to keto for 20 days, and then back to a Mediterranean diet for successful long-term maintenance.