Make sure that the diet has been studied extensively for safety — and discuss any changes with your physician or registered dietitian before beginning a new diet. (If you don’t have a dietitian, find one in your area at the Academy of Nutrition and Dietetics website.) And do a self-check to ensure the diet fits with your own values and preferences.
When it comes to the "best" diet for most people, this one consistently ranks at the top of every list. If you can't afford a cruise to the Mediterranean (yet!), at least you can eat like the beautiful, long-living, and famously healthy people from the region. The Mediterranean diet teaches you to eat like a Sardinian, one of the "blue zones" identified by researchers as having a high number of people living past 100—by eating more fish, olive oil, healthy fats, and fresh vegetables. The point is to have not just a longer life but also a healthier and happier one, whether you're trying to lose weight or not. (Really—research shows that you can reap the benefits of the Mediterranean diet without cutting calories.)

"The American Heart Association recommends that men eat less than 36 grams of added sugar and that women consume less than 24 grams. However, for optimal weight loss, I tell my male clients to consume less than 20 grams of sugar per day and I tell the women to consume less than 15 grams. The easiest way to cut back on the sweet stuff is by consuming less sugary drinks and dressings. Cut the sugar, lose the fat, regain your health and life." — Dr. Sean M. Wells, DPT, PT, OCS, ATC/L, CSCS
"Alcohol not only contributes extra calories, but often keeps company with juice/tonic, slows metabolism, triggers hunger, and can lead to poor food judgement (drunk people order cheese fries, not salads). 'A glass of wine' (or two) 5x a week definitely adds up. It may behoove you to go cold turkey on booze temporarily and see if it makes a different. Plus, alcohol can be rather bloating." — Monica Auslander Moreno, MS, RD, LD/N, nutrition consultant for RSP Nutrition

Research also finds that drinking frequently—even if it’s a moderate amount—can set you up for excess pudge. Not only do the beverages themselves contain unnecessary calories, but once you start sipping too much, your inhibition also plummets, according to one 2016 study. The result? You’ll have a hard time resisting that late-night slice of pizza. So if you're going to imbibe, be sure to stick to one drink per day for women and up to two drinks for men.


To prep his patients for success, Dr. Seltzer tells them to plan around a large evening meal by eating a lighter breakfast and lunch—NBD since most people who eat a meal before bed tend to wake up feeling relatively full, he says. Research suggests balanced bedtime meals may also promote steady next-day blood sugar levels, which also helps with appetite regulation.


According to its fervent proponents, humans were not made to be eating constantly; rather, we were designed to eat for short periods of time followed by hours (and sometimes days) of fasting. Much like vegetarianism, intermittent fasting is practiced for two main reasons: health and religion/spirituality. There are no food or caloric restrictions, but rather a restriction on WHEN to eat. The most popular methods include the 16/8 (8 hours of eating followed by 16 hours of fasting), the “Eat-Stop-Eat” method (two 24-hour fasts per week on non-consecutive days); and the 5/2 method (only 500 calories for 2 non-consecutive days, and 5 days of normal eating per week). While it's generally considered a healthy approach to eating when done moderately, some studies suggest extreme fasting may lead to hair loss and anxiety. 
“Intermittent fasting can be really challenging if you have an ever-changing schedule,” adds Hultin. “If you're traveling and crossing time zones, it could be very difficult to follow. It might be best for people with more stability in their lives.” Intermittent fasting isn’t safe for people with type 2 diabetes, children, pregnant or lactating women, or anyone with a history of an eating disorder.
The Dietary Guidelines is a joint report created by the Department of Health and Human Services (HHS) and the Department of Agriculture (USDA). It’s designed with the purpose of setting a general basis for what constitutes a healthy diet. The most recent Guideline was published in 2015 and will be updated in 2020. They include five key recommendations:
The easier it is to seamlessly fit a diet plan into your life without major lifestyle changes, the better. After all, by focusing on holistic long-term results rather than trendy short-term solutions, sustainability becomes the number one enemy of the feared “yo-yo” effect. During our investigative process, we asked ourselves: What makes a diet plan sustainable? After long hours of research, we decided that the following factors can determine a plan’s sustainability, and thus its odds of success: 
Research also finds that drinking frequently—even if it’s a moderate amount—can set you up for excess pudge. Not only do the beverages themselves contain unnecessary calories, but once you start sipping too much, your inhibition also plummets, according to one 2016 study. The result? You’ll have a hard time resisting that late-night slice of pizza. So if you're going to imbibe, be sure to stick to one drink per day for women and up to two drinks for men.
Even if you suffer from obesity, you don’t have to reach a “normal” BMI (more on this concept later) to reap the benefits that come with shedding some pounds. According to a Center for Disease Control and Prevention study, even a moderate weight loss ranging from 5 to 10 percent of the initial body weight can help you curb and prevent obesity-related illnesses. 

"It's no big surprise, but my go-to weight loss tip is to eat more vegetables. They are the most low-calorie food you can consume, and they're filled with health-boosting, satiating nutrients. From smoothies and eggs to soups, main and side dishes, they can fit in anywhere and boost volume and nutrition. If you want to eat more while still losing weight, veggies are your answer. —Laura Burak, RD, CDN
The idea is that the fasting induces mild stress to the cells in your body, helping them become better at coping with such stress and possibly helping your body grow stronger. The verdict is still out regarding the diet’s long-term effectiveness with weight loss, according to a review of preliminary animal research published in January 2017 in Behavioral Sciences. (17)
Research also finds that drinking frequently—even if it’s a moderate amount—can set you up for excess pudge. Not only do the beverages themselves contain unnecessary calories, but once you start sipping too much, your inhibition also plummets, according to one 2016 study. The result? You’ll have a hard time resisting that late-night slice of pizza. So if you're going to imbibe, be sure to stick to one drink per day for women and up to two drinks for men.
The plan promotes long-lasting, sustainable changes, and undoubtedly a bounty of research backs this up. In fact, one December 2013 study in the American Journal of Medicine shows that people following Weight Watchers were close to nine times more likely to lose 10 percent of their body weight, compared to people following a self-help diet plan. (20)
This may explain why the fat-burning effects of eating more protein were confirmed in a study published in the American Journal of Physiology. One group was fed a high-protein diet (just over 1 gram per pound of body weight per day) while the second group consumed an amount closer to the lower recommendation of the RDA (recommended dietary allowance). The group eating the higher-protein diet burned the most fat.
“A lot of people think the foundation of a paleo diet is high-fat meat, but I suggest that it’s vegetables,” says Hultin. The concept is to eat only foods — including meat, fish, poultry, eggs, fruits, and vegetables — that would have been available to our Paleolithic ancestors. This means grains, dairy, legumes, added sugar, and salt are all no-no’s.

"These diets are so restrictive that of course you're going to lose weight fast because you're not eating enough calories to sustain basic activities of your body, let alone any exercise. That's nothing that any person can sustain for the long term," Hogan said. "The weight's going to come back if you do lose any weight, and then it's going to be harder to lose weight in the future."
"I tell all of my celebrity and professional-athlete clients to get between 6 and 8 hours of sleep per night. Everyone is overly focused on food, water and exercise, all of which are extremely imperative to weight loss and optimal health. However, without proper sleep, all of these the other factors are null and void. When you don't get enough sleep, levels of the hormone leptin drop, which increases appetite. This surge in appetite makes comfort food more appealing, which can derail weight loss efforts." — Jay Cardiello, celebrity fitness and nutrition expert
Forget old low-carb diet plans that focused on processed protein bars and shakes. This year, the keto diet got high marks for low carb. Keto, short for "ketogenic," is all about training the body to burn fat for fuel. How? By eating fat—and lots of it. Most keto diets recommend getting at least 70 percent of your daily calories from fat and the rest from protein. The goal is to eat as few carbohydrates as possible. Proponents say it helps them drop weight fast with little or no hunger in addition to perks like more energy and mental clarity. (Interested? Here's everything you need to know about the keto diet.)
Flexitarian: A mix between the words “flexible” and “vegetarian”, the Flexitarian diet can be described as a vegetarian going on a short carnivore vacation. It is a mostly vegetarian diet that sometimes incorporates meat, fish, and poultry, and it is ideal for people who want to benefit from vegetarianism but cannot resist the temptation of animal products.  Also, a recent study suggests that, by going meatless from time to time, you may actually help in the fight against climate change. 
Phase 2: During this phase some carbs are back, so you have to watch out for any weight gain. (Following the strictness of Phase 1, you might be inclined to overeat your favorite carb-filled foods). You’ll get to eat no more than 50 grams of “good carbs” per day, including whole grains, beans, and fruits. Still, the bulk of your diet will consist of lean proteins, good fats, and vegetables.
It seems counterintuitive to drink lots of water when you’re looking to lose weight fast—especially water weight—but staying hydrated is one of the most important steps you can take to lose weight. People often mistake thirst for hunger, so staying hydrated allows you to be more in touch with the times when you are actually hungry, rather than just thirsty. Plus, a lot of good things happen to your body when you drink enough fluids.
The researchers hypothesize that participants who abstained from animal products dropped significantly more pounds since plant-based foods include loads of filling fiber and slow-to-digest complex carbs. Though more research is needed to confirm these results, the study authors write, "Vegetarian diets appeared to have significant benefits on weight reduction compared to non-vegetarian diets."
This popular diet program is fairly restrictive — and for the first 30 days, dieters must cut out grains, legumes, most dairy, added sugar, and alcohol without any slip-ups, according to the Whole30 website. (29) The aim is to “reset” your body and to adopt dietary habits resulting in weight loss. Cutting out added sugar and alcohol has merit, but all the restrictions prove challenging and could lead to nutrient deficiencies and disordered eating.
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Popularized by the documentary Forks Over Knives, the Ornish diet is a low-fat, plant-based diet plan based on whole grains, vegetables, fruits, and legumes. It's based on a lacto-ovo style of vegetarianism, allowing only egg whites and nonfat dairy products. It's packed with vitamins, fiber, and lots of filling plants to keep you satiated. Some studies have shown it can reverse heart disease and have beneficial effects on other chronic health conditions. (BTW, there is a difference between a vegan diet and a plant-based diet.)
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