Once you have begun your nutrition science career, you’ll find that many people think of “diet” as a dirty word, as it is frequently associated with depriving oneself for the sake of weight loss or as a means of correcting an imbalance like high cholesterol or diabetes. “Diet” simply refers to the kind of food you eat, and it is a synonym of “nourishment.” Rather than thinking of dieting as deprivation, think of it as a means for feeling and being healthier. Heath experts agree that there’s a nutrition-based science behind taking care of our bodies, and it requires our continuous dedication. On the other hand, we are also inundated with fad pill-based diets. Try to avoid giving into those, since they are usually based more on quick-fixes (and sapping money from you) than science.

One thing is certain, a typical diet in the United States is loaded with processed foods, high-fat dairy products, red meats, and sugars. All of these in concert can pave the way to an early grave, or at least a load of health problems. Whether you are looking into a nutrition science degree program or are a seasoned professional, it is important to expand your knowledge of long-term dietary lifestyles and preferences. Who knows? A client you could have may be interested or already participating in a special diet plan, and come to you looking for advice and guidance. To help you learn more, check out these popular dietary lifestyles.

#1: Mediterranean Diet

The inhabitants around the Mediterranean Sea are vaunted for their long life spans and low rates of cancer and cardiovascular ailments. Their diet tends to be low in red meat, sugar, and saturated fat. Instead, they eat lots of fruits, vegetables, whole grains, beans, nuts, legumes, olive oil, and flavorful herbs and spices. Seafood is preferred over other types of meat, and a moderate enjoyment of eggs, cheese, and yogurt is encouraged. Sweets and red meat are reserved for special occasions, but red wine and exercise are daily components.

#2: Weight Watchers

It is the ultimate brand name in structured, weight loss-oriented diets. Weight Watchers has been around since the 1960s, and boasts a legion of enthusiastic followers. The cornerstone of this program is its points system. Every food is allotted a certain number of points, and you’re allowed to eat a certain number of points a day. The system is designed to achieve a calorie deficit of 1,000 calories a day, meaning you’ll lose two pounds a week if you are faithful and stick with tracking your points. No foods are off-limits, and the Weight Watchers website catalogs 40,000 foods with their point values (no points for fiber-loaded fruits and veggies, high points for things like candy).

The biggest benefit of Weight Watchers is the support network that encourages members to attend in-person meetings a few times a month. Of course this is how the company makes money. A monthly pass to attend unlimited in-person meetings is $39.95, which also includes access to their eTools, or you can pay as you go. Meetings are $12 – $15 per week, with a one-time $20 registration fee. To only follow the meetings online, a three-month plan is $65. Weight Watchers teaches their participants how to choose between nutritionally dense foods and those with little value. This is a long-term lesson that can stick with you, should you decide to leave the program. Exercise is encouraged, plus you get bonus points (that allow you to eat more) for enough activity.

#3: Mayo Clinic Diet

This diet, developed by one of the country’s leading medical groups, is focused on breaking bad habits and picking up good ones. For the first two weeks, the Mayo Clinic Diet book instructs you to focus on the 15 key habits that are outlined by the authors These habits direct you to restrict certain foods, but allow unlimited snacking on fruits and vegetables. After two weeks, you shift your focus to calorie-counting, learning exercises, and nothing is off-limits. The idea is that during this time you’re supposed to develop a pattern of healthy eating consisting of fruits, vegetables, lean meat, high-fiber whole grains, and low-fat dairy. Alcohol is somewhat restricted, and exercise is part of the plan. The book costs about $20.

#4: Vegetarianism

It’s pretty simple, vegetarianism is when you stop eating meat. This diet allows you to lose weight and fend off chronic diseases. Of course some non-healthy items, like French fries, birthday cake, and ice cream, are perfectly compatible with a vegetarian diet. It’s really up to you to make good choices. This may be a difficult switch for hardcore carnivores, but if you’re already not putting meat at the center of every meal, going “veggie” shouldn’t be too stressful. Plus there are some pretty convincing meat substitutes available such as tofu and seitan. With vegetarianism becoming more popular, nearly every restaurant has a vegetarian option. There are even hundreds of cookbooks and websites that exist to support vegetarian lifestyles. Exercise isn’t an inherent element of a vegetarian diet, but it’s encouraged for everyone.

Veganism, or a vegan diet, means you do not eat any animal products and is touted as the more hardcore version of the vegetarian diet. It’s more of a philosophy or lifestyle than a diet. Vegans are often animal rights activists, and do not eat meat, eggs, dairy, any foods made with lard (refried beans), whey (margarine), or Jell-O (gelatin, which is made from animal bones and hooves). True veganism requires serious planning and commitment.

#5: Volumetrics

The theory behind volumetrics is that people tend to eat the same weight (as in literal poundage) of food each day, regardless of the number of calories. For example, a pound of low-density carrots contains as many calories as an ounce of high-density peanuts. So if you fill your plate with foods that are less energy dense, meaning they have fewer calories per gram, then you’ll be eating fewer calories without eating less food. It’s about making smart swaps, like sweet potatoes for white potatoes.

This is more of an eating pattern than a structured diet. The Ultimate Volumetrics Diet book is a good guide, developed by the diet’s original pioneer, Penn State University nutrition professor Barbara Rolls. The plan focuses on eating, and Rolls also recommends walking for 30 minutes most days of the week. This can be achieved by parking farther from the store, or getting off the bus a few stops early. The book costs about $15.

#6: Jenny Craig

This definitely falls closer to “structured diet” than “alternative dietary lifestyle.” In terms of how easy it is to use, nothing beats Jenny Craig. They send you a personalized meal and exercise plan, and assign a consultant to you for weekly one-on-one counseling sessions. While it’s easy to use, Jenny Craig can also be your most expensive dieting option. It’s a few hundred dollars for the initial registration fee, and each week of prepackaged meals costs $100 or more. However, you get half of your registration fee back if you stay within five pounds of your goal weight for one year, giving you a financial incentive. The portions are small, and some argue that Jenny Craig does all the thinking for you. As soon as you leave the program, you’re on your own to make the right choices (a fact that causes some to fall flat and gain the weight back). Jenny Craig’s program incorporates the Volumetrics approach. If you’re motivated to unofficially continue “Jenny Craig-ing,” then the Volumetrics diet plan is a useful reference guide. If you want some hand-holding and personal support, Jenny Craig may be right for you.

#7: Biggest Loser Diet

Trading on the popularity of the Biggest Loser television show, a number of books tout various methods to achieve the weight loss and healthy lifestyle of the show’s most successful participants. The diet encourages you to fill up on fruits, vegetables, lean protein, and whole grains; practice portion control; use a food journal; and exercise regularly (and with some intensity). The diet doesn’t ban any food groups, and there’s an abundance of recipes, online resources, and community forums to participate in. You’ll likely want to invest in one of the books, like 30-Day Jump Start or 6 Weeks to a Healthier You, which each run around $20. This is the most exercise-essential diet on this list, with the goal of educating you in body-weight training, aerobics, strength and resistance training, and yoga. In today’s television/computer-centric society, getting off the couch/office chair is always a good idea.

#8: Ornish Diet

In his 2007 book The Spectrum, Dean Ornish details a guide to achieve any goal — be it weight loss or reversing chronic disease. Ornish is a professor of medicine at the University of California, San Francisco, and the founder of the Preventive Medicine Research Institute; his method advocates responsible food choices, exercise, stress management, and seeking support from loved ones. All of this combines to have a positive impact on your health — and it’s certainly hard to argue with that. The most difficult part of the diet is its restriction of fat, which Ornish insists should be just 10 percent of daily calories. That’s reasonable, but it may be hard to achieve if you’re stepping straight over from a fast food-filled “Western” diet. The book costs about $15.

#9: Atkins Diet

One of the first big names in dieting, Atkins is a well-known and still popular carb-restricting diet. The science is simple: Carbs fuel the body, and if you restrict carbs, then the body will instead feast on stored fat. So feel free to eat a burger dripping with fat and melted cheese, but go bunless. Atkins has been proven to help people lose weight initially, but studies have shown that the effect (as with many quick-fix diets) is diuretic — you’re losing water weight, not fat weight. The actual success of this diet (or any diet) may simply be eating fewer calories, rather than cutting carb intake. The New Atkins for a New You costs around $15. The hardcore might go gluten-free, but it’s harder than veganism to stick with and is only necessary for those with celiac disease or some other gluten intolerance.

#10: Paleo Diet

The Paleo Diet has gained a lot of traction in the last few years as Americans have begun to yearn for the simpler lifestyle once lead by the caveman. It’s an easy leap: processed foods and carb-obsessed eating patterns weren’t things that the cave dwellers had access to. Paleo Diet-enthusiasts say we should get back to our roots; if a caveman didn’t eat it, you shouldn’t either. No more refined sugar, dairy, legumes, or grains; your entire plate should be filled with meat, fish, poultry, fruits, and vegetables. The diet hasn’t been deeply researched, it’s extremely restrictive, and health experts generally discourage eating so much red meat. Though there’s no set exercise plan, Paleo dieters are encouraged to move as much as their hunter-gatherer ancestors.

Honorable mention:

These two diets were developed by high-level health organizations, and the advice is both sound and free. They didn’t make the list of “most popular” because they’re not as well known, but they’re definitely worth a look.

The DASH Diet was developed by the National Heart, Lung, and Blood Institute and is a simple guide to smart eating: emphasize the foods you know are good for you and cut back on calorie- and fat-laden sweets and red meat, while also keeping an eye on salt consumption (which the majority of Americans consume way too much of).

We’ve saved the best for last: The U.S. government-endorsed TLC Diet was created by the National Institutes of Health’s National Cholesterol Education Program. It stands for Therapeutic Lifestyle Changes, and it’s also been endorsed by the American Heart Association as a heart-healthy regimen to reduce the risk of cardiovascular disease. In short: Cut back on fat, particularly saturated fat (fatty meat, whole-dairy milk, and fried foods), and eat more fiber. It was developed more to control cholesterol than for weight loss, and the only resource is this online manual, but the advice is certainly sound.

When you actively and safely invest time into planning what you eat, you’ll begin to find that the long-term gain of improved health outweighs any short-term satisfaction you get from consuming those not-so-healthy foods. Explore the rest of our website to find out what nutrition science is and what it takes to become a nutritionist or dietitian.