Nutritionists review top 10 trending diets

According to Google’s most recent annual rankings, these 10 diets were the most searched eating plans in the United States:

1. Paleo diet
2. Juice Cleanse diet
3. Mediterrenean diet
4. Master Cleanse diet
5. Ketogenic diet
6. Okinawa diet
7. Omnivore diet
8. Fruitarian diet
9. Pescetarian diet
10. Flexitarian diet

What are you leaving out by cutting back?

Read the reviews of these trending diets from registered dietitians and nutrition experts, so you can stay on track for a healthy lifestyle.

1. Paleo diet

Paleo diet has reached a recent explosion of popularity due to the Crossfit fitness program that advocates followers to subscribe to this eating plan.

Here’s a nutritionist review from Joan Salge Blake, an associate professor and registered dietitian at Boston University who blogs for Boston.com.

The crux of this eating plan is that our diet should mimic our hunter and gatherer Paleolithic ancestors. It is based on eating what you can hunt (meat, seafood) and gather (fruit, veggies). Dairy, grains, legumes, and starchy veggies such as potatoes, sweets, and juices are off-limits.

Benefits: If you have a sweet tooth and satisfy it daily, going Paleo will clearly cut calories. Since soda and bakery items were not available in the prehistoric days, they are not allow on this diet.

Downfalls: This unbalanced low-carb, high-protein diet ends up cutting calories because you are cutting out large categories of foods, as well as potential sources of important nutrients that your body needs. Keep in mind our Paleolithic ancestors had a life expectancy of about age 30. A well-balanced diet is a better bet for longevity.

2. Juice cleanse diet

People who follow a juice cleanse drink only fruit and vegetable juice. The idea is that removing the vitamins, minerals, and enzymes from the pulp allows the body to easily absorb nutrients. People who subscribe to juice cleanses claim that this practice eliminates toxins that have built up from normal eating habits, causing them to lose weight quickly and feel healthier.

Here’s a review from nutritionist Joy Dubost, of Dubost Food & Nutrition Solutions, an Academy of Nutrition and Dietetics spokesperson

Possible benefits may be the amount of fluids people need to consume in order to “cleanse’’ the system. For a healthy diet, the Institute of Medicine recommends 3.7 liters/day in males (130 ounces; the equivalent of 16 cups of fluid) and 2.7 liters/day for females (95 ounces; about 12 cups).

This diet can induce weight loss (mostly water weight), but at the expense of one’s health. Keep in mind once you stop the juice cleanse diet, the weight will typically be regained because normal eating will resume.

The biggest mistake is to think that your body needs assistance in removing toxins or detoxing. The body has a “built in’’ means of removing toxins through your liver, kidneys, and gastrointestinal tract. Therefore, you do not need to assist your body by following a diet that is ultimately unhealthy.

Some may find this beneficial if they need to “reboot’’ their system and get their diets or bodies back on track. From this standpoint, it is a mentally empowering approach rather than a physiological or health-based approach. In the short-term a few days may not be detrimental to long-term health, but other short-term symptoms may result such as headaches, bad breath, fatigue, and constipation.

Very restrictive diets, such as juice cleanses or other detox diets, can ultimately lead to a poor nutrition status (in some cases malnutrition) due to the lack of essential nutrients in the diet.

3. Mediterranean diet

The longevity of the people who live around the Mediterranean Sea give this eating plan its reputation. Many recent studies have also found data to support its nutritional effects on reducing heart disease and other chronic conditions.

Here’s a review from nutritionist Dr. George Blackburn, the director of the Center for the Study of Nutrition Medicine at Beth Israel Deaconness Medical Center.

The Mediterranean diet includes high consumption of breads and unrefined cereals, usually made from wheat. It also includes high consumption of fruits and vegetables, fish, cheese, olive oil, tree nuts (almonds and walnuts), moderate amounts of wine, and low amounts of meat and meat products. Other important elements of the diet are daily exercise, sharing meals with friends and family, as well as the pleasure of eating healthy and delicious foods.

Benefits: This diet is scientifically proven to help with long-term durable weight management/control. It also heightens the importance of home-cooked meals, and results in low incidence of coronary heart disease. It is the gold standard of healthy eating.

Downfalls: None

4. Master Cleanse diet

The Master Cleanse achieved recent buzz after Real Housewife of Beverly Hills star Yolanda Foster followed the cleanse ritual and encouraged her costars to try it on the Bravo television show.

Here’s a nutritionist review from Joan Salge Blake, associate professor and registered dietitian at Boston University and

Boston.com blogger

The theory behind this diet is that you need to routinely “cleanse’’ or “detox’’ your body to get it into shape. The diet usually involves drinking a concoction of lemon juice with maple syrup and cayenne pepper or whatever is the fad ingredient of the moment.

Benefits: Absolutely none.

Downfalls: Your liver is your body’s ultimate cleansing and detox machine. By going on a cleanse, you are reducing your calories to a very low level, and thus, will not be consuming enough of the essential nutrients that your body needs. If you are not consuming enough protein and calories to meet your daily needs, your body will begin to break down your lean muscle mass for the protein that it needs. By doing this, you will lower your metabolic rate, which is not a good thing in the long run if you are trying to lose weight.

5. Okinawa diet

The Okinawa diet has regained popularity due to the release a New York Times bestseller by the same name in which two physicians advocate for this region-based eating plan and lifestyle because of the longevity of the people who live on the Japanese island.

Here’s a review from nutritionist Kate Sweeney, the manager of the Nutrition Consultation Service at Brigham and Women’s Hospital.

The Okinawa diet is based on the eating habits of people from Okinawa, a Japanese island home to the longest living individuals on the planet. On Okinawa, people consume diets high in vegetables and soy, low in red meat and dairy, with almost no refined carbohydrates.

This diet focuses on calculating the caloric density of foods by dividing the amount of calories in a given food by the weight in grams. This number is used to classify foods into four categories; featherweights (least calorically dense), lightweights, middleweights, and heavyweights (most calorically dense). The general concept is to eat unlimited amounts of featherweight foods and limit consumption of heavyweight foods.

Benefits: Looking at the caloric density of foods by calculating a simple number is an easy and quick way to compare foods to help make better food choices. In this diet, the staple is the “featherweight’’ foods such as fruits, vegetables, and tofu, all of which represent healthy options. This diet also recommends limiting various high-calorie foods, a strategy that is especially helpful for weight loss.

Downfalls: This diet focuses solely on calories, which is not the only important factor in making healthy choices. For example, peanut butter and other nuts are calorically dense, but they provide essential healthy fats and other vitamins and minerals that are linked to heart health and other great benefits. Lumping nuts into the same category as ice cream and cookies can lead to an individual missing out on another big part of the nutrition and weight loss picture— nutrient density!

6. Fruitarian diet

The next level of a raw food diet, fruitarians only eat foods technically considered to be botanical fruits. Ethically they believe they should only eat plans that spread their seeds by being consumed. So root vegetables are off-limits. The diet surged again in popularity when Ashton Kutcher was hospitalized after eating only fruit for a month.

Here’s a review from nutritionist Marci E. Anderson, a registered dietitian in Cambridge.

There are many different ways to follow the fruitarian diet. In general, the diet poses major nutrient deficiencies if followed over time. Most notably, these include protein, essential fatty acids, B vitamins, calcium, iron, zinc, and Vitamin D. Additionally the risk of food obsession and social isolation due to such severely limited food options are also worth mentioning. Often the motivation for following a fruitarian diet is ethical. My best suggestion would be to work with an experienced registered dietitian to find a balanced eating plan that supports your moral belief system as well as your physical, mental, and emotional well-being.

7. Pescetarian diet

The pescetarian diet offers a protein-rich alternative to a vegetarian lifestyle. Some even look to pescetarianism as a meatless alternative to paleo. The fatty-acid rich fish provides a lean protein alternative that studies have shown can have large nutritional benefits for followers.

Here’s a review from nutritionist Alicia Romano, a registered dietitian at Frances Stern Nutrition Center, a part of Tufts Medical Center.

The pescetarian diet is a vegetarian diet that includes all fish and shellfish in addition to grains, fruits, vegetables, seeds, nuts. This diet may or may not include dairy products, but excludes meats and poultry.

Benefits of the pescetarian diet are similar to those of Vegetarian diets, which may include a lower risk of heart disease, hypertension, and type 2 diabetes. Vegetarians also tend to have a lower body mass index (BMI) and lower overall cancer rates. This diet is lower in saturated fat and higher in fiber.

The pescetarian diet includes a larger amount of omega-3 fatty acids (EPA/DHA), which traditional vegetarian diets may lack, and offers a versatile protein source.

Women who might become pregnant, women who are pregnant, women of childbearing age, and children should avoid high mercury fish and shellfish (shark, swordfish, king mackerel, and tilefish). Up to 12 ounces per week of a variety of fish and shellfish low in mercury are safe to consume in these populations. Other downfalls may include lower intakes of vitamin B12 and potentially lower calcium intakes (if avoiding dairy and calcium-rich vegetables). Limited protein options (when avoiding meat, eggs, dairy, and poultry) may pose as another downfall and open the doors to choosing imitation vegetarian “meats’’ that may be more processed.

8. Ketogenic diet

The ketogenic diet was designed in the 1920s by Mayo Clinic physician Dr. Russell Wilder to treat epilepsy before modern-day antiseizure medication was available. It has since regained popularity with the publication of Dr. David Perlmutter’s recent New York Times bestseller “Grain Brain,’’ which argues for eliminating carbohydrates and sugar, but not eliminating fats from our diets in order to prevent chronic illness and other health issues.

Here’s a review from nutritionist Dr. Caroline M. Apovian, the director of the Center for Nutrition and Weight Management at Boston Medical Center, and a professor of medicine at Boston University School of Medicine.

A ketogenic diet is a diet high in fat and protein and almost no carbohydrate. This creates a state of ketosis from the lack of a glucose source. Ketone bodies are produced from fat metabolism, and they are used as a fuel source instead of glucose. Ketogenic diets have been used in children to treat seizure disorders and also by bodybuilders as a way to lose weight while retaining as much muscle mass as possible. The Ketogenic diet has come back into vogue as yet another low or no carbohydrate diet similar to the Atkins diet.

Benefits: You can lose weight on any diet as long as you decrease caloric intake, and therefore you can lose weight on this diet too. It is very similar to the Atkins diet. The ketosis makes you feel less hungry and in fact can take away your hunger and that is why many dieters loved the Atkins diet. Weight loss is fast, and the ketosis gives you a good feeling at least for some people.

Downfalls: It completely eliminates carbohydrates, so it can be dangerous as you are therefore eliminating essential nutrients, such as vitamins, minerals, and fiber. It is not a good long-term solution for weight loss. It can cause dehydration due to the lack of carbohydrates, and thus when you introduce carbohydrates there is a sudden weight gain due to water retention.

9. Omnivore diet

The omnivore diet, with the root of the word literally meaning “everything,’’ most closely follows a typical person’s eating habits, distributing nutrition from all five main food groups, and eliminating none. Although it’s not a standard diet plan, studieshave demonstrated that omnivores have nutritional benefits over other diets like vegetarianism. The term regained some popularity following food activist and journalist Michael Pollan’s book, “The Omnivore’s Dilemma,’’ which asks, what should you eat if you can eat anything?

Here’s a review from nutritionist Dr. Caroline M. Apovian, the director of the Center for Nutrition and Weight Management at Boston Medical Center, as well as a professor of medicine at Boston University School of Medicine.

This is a meat-lovers’ diet much like the Paleo diet. Protein, vegetables, and fruits with high water content are allowed. Meat is eaten three days of the week with salad and cooked vegetables. Carbs such as bread and potatoes and rice are added to certain meals in addition to dairy.

Benefits: The concept of eating some meat when you can get it, as well as vegetables and fruit, make this diet very good for those needing to lose weight. The high protein staves off hunger, but there are also balanced amounts of whole grains, potatoes, rice, and dairy. Fruits with high amounts of water are allowed.

Downfalls: This is a hard plan to follow. There is no scientific basis for why you can have certain meals a few days per week.

10. Flexitarian diet

A popular option for vegetarians who don’t quite want to go all the way, the Flexitarian diet has been a trending diet for years, but recently achieved Internet buzz fame again in 2012 when it earned an official entry as a new word in the Merriam-Webster Dictionary, the same year as “sexting.’’

Here’s a review from nutritionist Alicia Romano, a registered dietitian at Frances Stern Nutrition Center at Tufts Medical Center.

The Flexitarian diet is an “almost vegetarian diet,’’ where the aim is to focus on more plant-based foods, and decrease portions of animal-based proteins. According to the diet book, “The Flexitarian Diet: The Mostly Vegetarian Way to Lose Weight, Be Healthier, Prevent Disease and Add Years to Your Life,’’ advanced flexitarians avoid meat three to four days per week while ‘experts’ go meatless five or more days a week.

Benefits: A well-planned flexitarian diet has the potential to reap some of the benefits of a vegetarian diet, without completely cutting out meat. This includes decreased intake of saturated fat, which has the potential benefit of lowering LDL and total cholesterol levels. There’s also a potential decrease in calorie intake by replacing animal proteins with vegetarian proteins. Flexitarian diets encourage a higher fiber intake by including more plant-based foods and whole grains, which may have health benefits and allow for a higher intake of vitamin B12 and heme iron. This diet offers more flexibility in terms of protein options and eliminates “boredom’’ that may be experienced for those reluctant to follow a strict vegetarian diet.

Downfalls: The diet may be too flexible and pose as an ineffective diet for those that require more structure or concrete diet recommendations for “success.’’ Additionally, this diet does not give real guidance on how to substitute all protein sources (for example, there is no advice given for more processed meats or fatty meats). If not planned appropriately, saturated fat intake can still be high in this diet. If you are not willing to experiment in the kitchen with extra vegetables or new protein sources, this diet may not be the best option for you.

Healthy eating

According to Joy Dubost, an Academy of Nutrition and Dietetics spokeswoman, there is no “magic bullet’’ for safe and healthful weight management.

“Successful weight management is a lifelong process. It means adopting a lifestyle that includes a healthful eating plan coupled with regular physical activity,’’ she said. “Weight loss in the range of one to two pounds per week is considered safe, and allows the individual to learn to manage food and drink intake while still getting the important nutrients his or her body needs.’’