Top Fad Diets: Love Them or Leave Them?

The gluten-free diet, Fast Diet and Paleo diet are trending. But should they be?

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Each year, a slew of diets – some new and some recycled – are unleashed upon millions of folks looking for the quickest way to shed pounds. Diet promoters promise quick results, and die-hard advocates offer wholehearted testimonials. Many of these diets are targeted to folks who may already have a negative self-image, as well as those looking for the next scientific-sounding diet that really works. 

Toby Amidor
Toby Amidor
Before choosing to embark on any new diet adventure, do your homework to understand what the diet is really about and if it's safe and effective for you. To help you get started, here's an overview of four popular diets:

Gluten-Free Diet 

You don't necessarily need to have celiac disease or gluten-sensitivity to embark on this diet. Rather, people are adopting a gluten-free diet to lose weight. All foods containing wheat, barley and rye (such as pasta and traditional baked goods) are avoided, while whole foods like fruits, vegetables, beans, lentils, dairy, healthy fats and seeds are promoted. 

Pros: 

• Lots of whole foods are included, and these are always healthy choices.

• There is a tendency to steer clear of packaged and processed foods, which tend to be high in sodium and preservatives. 

Cons 

• A wide variety of gluten-free packaged foods are now available, but many are loaded with more sugar and fat than their gluten-filled counterparts. This makes it easy to splurge, even on gluten-free foods.

• Large portions of any foods (such as gluten-free breads or potato chips) can lead to weight gain.

• Avoiding gluten-containing whole grains can decrease the spectrum of nutrients taken in. 

[Read: What is the 'Best Diet' for You?] 

Intermittent Fasting 

This diet ranked No. 28 of 31 on U.S. News's Best Diets Overall rankings list. 

The theory behind it is that our bodies were programmed for periods of feast and famine. As such, we should recreate these feast and famine days in order to lose weight and live a longer life. 

On this plan (also called The Fast Diet), dieters select two non-consecutive days each week to eat 500 or 600 calories, depending if they're a man or woman. On fasting days, low-glycemic-index and low-glycemic-load foods are recommended since they take longer to digest, which in turn makes you feel more satisfied. Recommended foods include vegetables, nuts, seeds, legumes (including beans and lentils), and some fruit. Dieters are recommended to follow their regular exercise regimen during fasting days. During the remaining five non-fasting days, you can eat whatever you wish. 

Pros 

• All food groups are allowed.

• Exercise is promoted. 

Cons 

• Much of the scientific evidence regarding intermittent fasting is controversial.

• With suboptimal calories consumed twice a week, you may become deficient in several important nutrients.

• Eating so few calories can result in uncomfortable side effects such as headaches, irritability and hunger.

• Lifelong healthy eating habits aren't promoted. 

[Read: The Case For Skipping Meals.] 

Paleo Diet 

This diet ranked dead last on U.S. News's Best Diets Overall rankings list. 

The caveman-inspired Paleo diet has a strong following, and revolves around eating like our Paleolithic ancestors – who lived by hunting and gathering. Creators claim that by following this plan, you can increase athletic performance, become naturally lean and eliminate acne. Additionally, the increased consumption of fruits and vegetables is thought to improve symptoms of diseases like osteoporosis, asthma and high blood pressure. 

The Paleo diet encourages fresh fruits and vegetables, seafood, lean meat, and healthy fats (such as olive oil and flax seed). It discourages refined sugars and grains, saturated and trans fat, salt-processed foods and yeast, dairy, and whole grains. It also encourages fun and engaging exercise.

Pros 

• Lean meats and plenty of fruits and vegetables are recommended.

• This plan tends to be low in sodium.

• Exercise is highly encouraged. 

Cons 

• Entire food groups – such as whole grains and dairy – are eliminated, making it tougher to take in essential nutrients, including calcium and vitamin D.

• Choosing the wrong types of meat (those that aren't lean) can increase your risk for heart disease.

• Many folks tend to get stuck on the same foods, which limits overall nutrient intake.

• Can be dangerous to follow for those with specific diseases (like kidney disease).

• Purchasing fresh grass-fed and free-range meat, fish and seafood can be pricey. 

[Read: Quiz: What Do You Know About the Best Diets?] 

Raw Food Diet 

This diet ranked No. 29 of 31 on U.S. News's Best Diets Overall rankings list. 

The raw food movement has been around for years, but folks are now turning to it in order to lose weight. On this plan, food is never cooked above 116 degrees Fahrenheit in order to keep the food's enzymes intact. Raw foodists emphasize fresh fruits and vegetables, nuts, seeds, herbs, and miso. Off-limits choices include bread, beans, lentils, pasta, meat and eggs. Some followers choose to consume unpasteurized milk and cheese, along with raw fish and meat. 

Pros 

• Lots of fresh fruits and vegetables are recommended , as are healthy fats from nuts and seeds. 

Cons 

• Requires tedious meal preparation and special equipment, which can be costly.

• Consuming unpasteurized dairy foods and uncooked fish and meat can lead to foodborne illnesses such as Listeria and E. coli.

• Eliminating numerous food groups (including grains, legumes and animal products) over long periods of time can lead to vitamin deficiencies.

• It's very tough to dine out and have diet-approved food available at social events and parties. 

My recommendation: If you're thinking about trying a new weight-loss plan and feel there's something unsafe or questionable, seek the advice of a physician and registered dietitian who can help guide you in the right direction. Your health and well-being should be your number one concern. To find a registered dietitian in your area, log onto Academy of Nutrition and Dietetics website and click on the green button that says "Find A Registered Dietitian." 

[Read: 2014 Food Trends: What's Hot at Restaurants.] 

Hungry for more? Write to eatandrun@usnews.com with your questions, concerns and feedback. 

Toby Amidor , MS, RD, CDN, is the owner of Toby Amidor Nutrition and author of the forthcoming cookbook "The Greek Yogurt Kitchen" (Grand Central Publishing 2014). She consults and blogs for various organizations including FoodNetwork.com's Healthy Eats Blog and Sears' FitStudio.