1. Dr. Mehmet Oz, America's Doctor Though he’s no wizard, Dr. Oz certainly is pretty magical. Since 2009, Oz has hosted his Emmy Award-winning show and amassed a huge fan following. Before that, he was the leading health expert on Oprah for more than five seasons. Though he’s conjured up some debate over his legitimacy and ties to controversial weight-loss and health products, Dr. Oz has influenced millions of viewers, readers of his magazine columns and bestselling books, and the medical community at large (Oz has published on topics ranging from cardiac surgery, to complementary medicine, to health care policy, among others). Oh, and in his free time, he performs heart surgeries. His next venture? A brand new lifestyle magazinedue out early next year. 2. Arnold Schwarzenegger, The Then-and-Now Fitness Icon He’s back! Last year, the Governator re-launched his website and released his autobiography, “Total Recall: My Unbelievably True Life Story.” Though he’s had some glaring issues in his personal life, Schwarzenegger made a splash in the October issue of Muscle and Fitness (where he’s Executive Editor) when he showed that he's still got the burly muscles he's known for. At 66 years old, Schwarzenegger is as motivated as ever. He pumped out several films in 2013, including “The Escape Plan” with fellow fitness icon Sylvester Stallone. Somehow, between taking care of gubernatorial duties and speaking engagements, "The Oak" even managed to release his new line of nutrition supplements this fall. 3. Mark Bittman, The Vegan (and Writer) Before 6pm As one of the most respected food and health journalists around, Bittman's work has spanned topics from super basic cooking techniques (like how to boil water... seriously) to global warming and food ethics. While the veteran New York Times writer could be considered an expert on gourmet food, his book, “How to Cook Everything,” provides readers with straightforward pantry-stocking skills, strategies for eating healthy away from home, and plenty of tips for home cooking. This past year, Bittman released his new book, “VB6: Eat Vegan Before 6:00” which chronicled his decision to adopt healthier eating habits instead of going on medication for pre-diabetes. We can't wait to see what he cooks up next. 4. Michelle Obama, The First Lady of Kids' Health Let’s get one thing straight: The First Lady is known for a whole lot more in the health and fitness space than just those incredible biceps (although we understand why people can’t stop talking about them). Obama is passionate about teaching children the importance of eating healthy and getting active through her Let’s Move initiative. This year, she appeared on Sesame Street to talk about the value offruits and veggies and teamed up with the Partnership for a Healthier America for Drink Up, a campaign encouraging Americans to drink more water. More recently, the White House mom joined with the President to urge Americans to enroll for health care coverage in the wake of massive health care reform. This is one First Lady who's making a huge mark on the nation's health and wellness. 5. Dr. Sanjay Gupta, Chief Medical Correspondent As the chief medical correspondent for CNN, Gupta is a familiar face in living rooms all over the nation. A practicing neurosurgeon, he’s got enough medical chops and health know-how that President Obama even asked Gupta to be surgeon general during his first term. Though the doc declined, he’s done a lot to educate the public about the latest medical advances, global health news, and disaster relief while travelling the world to provide exclusive on-scene coverage. This year, Gupta stirred up controversy with "Weed," a new documentary in defense of medical marijuana that resulted in a Colorado pot dispensary naming a new strain after him. We're not sure whether that's flattering or not, but it does show that Gupta's influence is spreading like never before. 6. Tim Ferriss, Paragon of Efficiency Referred to as the “4-Hour Man” Ferriss knows a thing or two about getting sh!t done — and fast. The superhuman has been offering up secrets to mastering efficiency and productivity for years with New York Times bestselling books including “The 4-Hour Workweek,” “The 4-Hour Body,” and "The 4-Hour Chef." His renowned blog is chock-full of lifehacking tips and tricks, though they may not be accessible to all readers (not everyone has the time, money, willpower, or connections Ferriss does). But to many, there’s something undeniably enticing about his way of life. That's why, in 2013, he became the star of his own TV show, "The Tim Ferriss Experiment," which follows the man as he attempts to master a new skill every week, from parkour to drumming in a rock band. 7. Jillian Michaels, The Butt-Kicking Workout Buddy This tough-as-nails trainer is best known for her role on The Biggest Loser," where she’s part butt-kicker, part lifestyle coach, and part weight-loss mentor. She’s a New York Times bestselling author, and you can also find her in dozens of fitness DVDs — and even video games. Though Michaels hit the headlines in 2013 for a less-than-stellar performance in the Malibu triathlon, she’s still inspiring others with her newly released workout DVD, "Yoga Inferno," and her “Maximize Your Life” speaking tour, which focuses on goal-setting, happiness-making, and harnessing potential. 8. Shaun Thompson, The Insane Trainer While most people recognize this chiseled, as-seen-on-TV trainer as Shaun T, he does in fact have a last name. (It’s Thompson.) After dabbling in theater, television, and dance (ahem, he was a backup dancer for Mariah Carey), Thompson inched his way into fitness with the super-successful "Hip Hop Abs" program. Continuing his relationship with home fitness giant Beachbody, Thompson became a household name with his 60-day workout challenge, "Insanity" — considered one of the most challenging and effective home workout DVDs. Not one to step backwards, the likeable trainer upped the ante with two more (even harder) iterations of Insanity in 2011 and 2012. During a very busy 2013, Thompson decided to target people strapped for time with his "Focus T25," program, designed to cram in an hour’s worth of fitness results into 25 minutes. He also launched ShaunTFitness.com and the Shaun T Store, cementing his place as one of the biggest commercial fitness successes in history. 9. Michael Pollan, Mr. Food Rules Since his groundbreaking book, "The Botany of Desire," was published in 2002, Michael Pollan has been challenging the way we think about food. His philosophy can be distilled to his 7-word mantra: “Eat food. Not too much. Mostly plants.” As an advocate for local and seasonal food (both for human and environmental health), Pollan has gained acclaim for his many books including "The Omnivore’s Dilemma," "In Defense of Food: An Eater’s Manifesto," and "Food Rules: An Eater’s Manual." His latest work, “Cooked,” released in 2013, explores the role of four classical elements in cooking — fire, water, air, and earth — with lessons ranging from grilling and boiling to more complex ventures like fermentation. When it comes to agricultural policy and food writing, this guy is a big deal (and there’s no sign of him stopping any time soon). 10. Dr. Marion Nestle, Food Policy Mover-and-Shaker With a Ph.D. in molecular biology and a Masters in Public Health, Nestle has made nutrition and food her passion. She’s published books on food politics for both humans and pets, and most recently covered all aspects of the humble calorie in her book, "Why Calories Count: From Science to Politics." She writes articles for The Atlantic in addition to almost-daily blog posts about food news, nutrition labels, and policy. This year she’s still going strong, lecturing on food politics at universities, book fairs, and libraries worldwide. 11. Dr. Drew Pinsky, The Doctor Who Puts Stuff Out There When he’s not counseling reality television stars on "Teen Mom," this board-certified doc is busy with his self-titled podcast; nationally syndicated radio show, “Loveline;” and writing books such as the massively popular New York Times bestseller, "The Mirror Effect: How Celebrity Narcissism is Seducing America." A few years back, Pinsky co-authored the first academic study on celebrities and narcissism, which drove a hefty amount of online coverage. After undergoing surgery for prostate cancer last year, a fully recovered Pinsky has spent much of the last year advocating for men’s health. 12. Jamie Oliver,The Healthy Change-Making Chef This British chef first hit the scene as the energetic host of "The Naked Chef" in 1999. In the years following, Oliver capitalized on his fame by opening restaurants and publishing scores of cookbooks (including "Jamie's Food Revolution" and "Cook with Jamie"). Lately, he’s best known as an advocate for healthier cafeteria meals in schools in the U.S. and abroad. Though he’s gotten a bad rap for his in-your-face tenacity, the importance of his philanthropic missions to make people’s lives healthier and happier can't be overstated. He’s trained troubled youths to enter the restaurant business, raised awareness about ethical fishing, created the Jamie Oliver Food Foundation, and received the 2010 TED prize for his many campaigns to create change on both individual and governmental levels. This year and next, Oliver’s foundation is on tour to improve health and spread food education with free training, basic home cooking classes, and recipes. 13. Dr. David Katz, Nutrition Trailblazer You think your schedule’s packed? It’s probably a walk in the park compared to Katz’s daily duties. The board-certified preventative medicine expert founded and leads Yale University’s Prevention Research Center, serves as a clinical instructor of medicine at the Yale School of Medicine, is founder and President of the nonprofit Turn the Tide Foundation, is Editor-in-Chief of the medical journal Childhood Obesity, and regularly writes articles on nutrition and preventative health for publications as diverse as The New York Times and O the Oprah Magazine, among other accomplishments. Katz is also an inventor with several patents to his name, and is the mind behind the NuVal nutrition system (currently used in thousands of supermarkets across the country), which scores foods on a scale from 1-100 based on nutritional value to help consumers make healthier purchases. 14. Dr. Andrew Weil, Natural Health Educator When treating health problems, many doctors slap a figurative a Band-Aid on the obvious problem and call it a day. Such is not the case at the Center for Integrative Medicine at the University of Arizona, where practitioners take a mind-body approach to wellness and where Dr. Weil is the director as well as a professor of medicine and public health. In addition to teaching, Dr. Weil runs Weil Lifestyle, a company that sells natural health products and services, and the non-profit Weil Foundation, which aims to educate the public, train healthcare professionals, and even change public policy to support preventative, holistic health care. He’s written hundreds of scientific articles and 13 books, including "True Food: Seasonal, Sustainable, Simple, Pure," which was published in late 2012. 15. Bob Harper, Trainer Extraordinaire It was a busy year for this “The Biggest Loser” trainer. Harper published his third book, "Jumpstart to Skinny: The Simple 3-Week Plan for Supercharged Weight Loss," which elaborates on some of the themes and techniques first described in his 2012 book, "The Skinny Rules: The Simple, Nonnegotiable Principles for Getting to Thin." Both publications are part of Harper’s larger fitness empire, which includes workout DVDs, supplements, training programs, and motivational speaking. Since coming out as gay on "The Biggest Loser" this year, he's been an even larger source of inspiration for contestants struggling to accept and celebrate their own sexuality. 16. Bethenny Frankel, The Low-Cal Drink Girl This former “Real Housewife of New York City” has successfully leveraged her show-biz experience into a full-blown career as a talk show host, blogger, businesswoman, and lifestyle guru. In 2013, Frankel enhanced her celebrity with her own television talk show, called “bethenny,” in which she covers everything wellness-related, from relationships, to food, to health, to beauty. This year, she also launched several new products for her SkinnyGirl line of low-calorie alcoholic beverages, including a whole line of wines, flavored vodkas, and several new cocktail mixes. 17. Dr. Deepak Chopra, The Ultimate Spiritual Guide Got questions about your mental and physical health? Chopra may have some answers (or even more questions) for you. The author, holistic health advocate, and alternative medicine practitioner is all about challenging traditional Western ideas regarding health and medicine. Chopra’s website is a one-stop shop for those curious about alternative treatments — you can buy calming supplements, feng shui books, meditation videos, and more. He's also collaborated with the one and only Oprah to inspire and create a "global meditation community" via online meditation courses. In 2013, Chopra published several books, including "What Are You Hungry For?," "Brotherhood, God: A Story of Revelation," and "Super Brain: Unleashing the Explosive Power of Your Mind to Maximize Health, Happiness, and Spiritual Well-Being." 18. Tony Horton, The P90X Guy After developing the world-famous "P90X" workout plan and DVD, Tony Horton hardly rested on his laurels. He’s since developed dozens of exercise programs, including "P90X2," "10-Minute Trainer", and his most recent addition, "P90X3." To date, he's completed four tours with Armed Forces Entertainment, including his most recent, "Ripped and Ready," during which he traveled around the world to inspire members of the armed forces (and their families) to adopt fitness regimes geared specifically to them. He also manages ASH Fitness in Santa Monica, California, and has created a line of performance eyewear, written multiple books ("Bring It!: The Revolutionary Fitness Plan for All Levels that Burns Fat, Builds Muscle, and Shred Inches" and "Crush It!: Burn Fat, Build Muscle, and Shred Inches with the Ultra-Extreme Warrior's Workout"), and launched a line of exercise products, videos, and accessories. 19. Lisa Lillien, The Calorie-Cutting Cook Lillien’s tagline says it all: “Hungry Girl is not a nutritionist. She’s just hungry.” From these humble beginnings, Lisa Lillien has created an empire (including a super-popular blog, a column on the Weight Watchers website, and her own show on Food Network) based on her unabashed love of food and her candid struggles with eating healthily. Lillien calls herself a “foodologist” because, although she lacks official credentials, she’s enthusiastic about eating and helping people stay healthy without ditching their favorite foods. Her website features healthy recipes, diet tips, and plenty of words of encouragement. Lillien is also the author of eight books (all of which were New York Times bestsellers); in 2013, she published "Hungry Girl 200 Under 200 Just Desserts: 200 Recipes Under 200 Calories." 20. Tony Robbins, Mr. Motivation Self-help professional and motivational speaker Tony Robbins has made it his life goal to empower people to change their own lives. His programs, motivational speaking events, books, DVDs, and seminars aim to help people build strong relationships, be healthy for life, achieve professional success, find inner balance, and accomplish personal growth. His most popular seminars include titles like "Unleash the Power Within," "Ultimate Relationship," "Ultimate Edge," and "Business Mastery." Robbins also offers personal coaching services. In 2013, he released an e-book, "Re-Awaken the Giant Within," which is a follow-up to his 2007 self-help bestseller, "Awaken the Giant Within." 21. Rich Froning, The Fittest Man on Earth Feeling pretty strong after that set of push-ups? Welcome to Rich Froning’s world. The CrossFit athlete has been named the “Fittest Man on Earth” after winning the CrossFit Games in 2011, 2012, and 2013. He is the first competitor ever to achieve that record at the Games. In 2012, Froning opened his own gym, CrossFit Mayhem, in Tennessee, where he works as the head coach. Froning has the credentials to back up his work: He's working toward his Masters in Exercise Science, is a certified Crossfit Level 1 instructor, and holds a certification in Crossfit Olympic Lifting. In 2013, he penned a memoir about his successes inside and outside the gym, entitled "First: What It Takes to Win." 22. Jeanette Jenkins, The Hollywood Trainer With a roster of A-list clients including P!nk, Alicia Keys, Queen Latifah, Serena Williams, Kimora Lee Simmons, and even Olympic athlete Carmalita Jeter, Jenkins definitely has her hands full. In addition to training celebs, the fitness expert is the founder and President of the The Hollywood Trainer and has created a popular collection of fitness DVDs, written a book about staying fit ("The Hollywood Trainer Weight Loss Plan: 21 Days to Make Healthy Living a Lifetime Habit"), and appeared on shows such as The Today Show, the Dr. Oz Show, and Celebrity Fit Club. She’s contributed her exercise expertise to publications including USA Today, Fitness magazine (where she's served on the advisory board for 11 years), Shape, Health Magazine, Self, O Magazine, and dozens of other major print publications. This past year, Jenkins made time in her busy schedule to release a new exercise video, "Sexy Abs Cardio Sculpt," and be a featured trainer on the Nike Training Club app. 23. Mark Sisson, The Paleo King Fancy yourself a modern-day caveman? Then head over to Sisson’s site, Mark’s Daily Apple, which has become a mecca for those interested in the Paleo lifestyle. There, Sisson espouses a down-to-earth, no-nonsense approach to health and fitness. With a super-active discussion forum, daily blog posts, workouts, and plenty of resources for “going primal,” Sisson’s site is the biggest Paleo resource on the web right now. His company, Primal Blueprint, offers coaching, nutritional supplements, nutritional counseling, and educational materials. This year, the prolific writer released his seventh book, "The Primal Connection: Follow Your Genetic Blueprint to Health and Happiness." 24. Joy Bauer, The TV Nutritionist Eating nutritiously doesn’t have to be boring, as evidenced by Joy Bauer’s collection of vibrant, flavorful, and creative recipes. Bauer, a registered dietitian and nutritionist, shares her considerable knowledge with the world as the nutrition and health expert for "The TODAY Show;" she also hosts the program's "Joy Fit Club," among other regular series. In addition to her career on the small screen, Bauer writes daily blog posts, contributes articles to Woman’s Day and Fitness Magazine, stars in a popular YouTube series called "What the Heck Are You Eating?," and has published multiple books about diet and weight loss, including "The Joy Fit Club: Cookbook, Diet Plan & Inspiration" and "Slim and Scrumptious." She somehow also finds time in her schedule to host RLTV's "Good Food, Good Deeds" and serve as the exclusive nutritionist for the New York City Ballet. 25. Eric Cressey, Strength Sensei Any man with a gym named after him has got to be serious about fitness, right? Cressey Performance, an elite-level facility located outside Boston, is different from most health centers filled with treadmills, a weight rack, and little else. Cressey focuses on strength and conditioning — he has degrees and certifications in kinesiology, strength and conditioning, sports and fitness management, and exercise science. The certified coach uses his extensive knowledge to train elite athletes (especially professional baseball players) as well as contribute hundreds of articles to publications like Men’s Health, ESPN, The Boston Globe, and Triathlete Magazine. In October, Cressey released "The High Performance Handbook," a complete guide to strength and conditioning that includes programs for all levels of athletes, plus videos and nutrition plans. 26. John Romaniello, The Titan of Testosterone The man better known as “Roman” had a very busy 2013: He got married, launched FitBox (a monthly subscription box jam-packed with fitness-related goodies), and (along with fellow Influencer Adam Bornstein) co-wrote his first book, "Engineering the Alpha," which debuted on The New York Times Bestseller List. The personal trainer's specialty is fat loss, and his cutting-edge techniques emphasize the importance of intermittent fasting and hormone manipulation. For those who have wondered if there's a shortcut to building muscle and burning fat, Roman's sneaky tricks to maximize testosterone and growth hormone might be the best place to start. These days, he's working on his next book, advising fitness startups, and training clients via his company, Roman Fitness Systems. 27. Dr. Joel Fuhrman, The Nutritarian Joel Fuhrman is known for coining the word “nutritarian,” a person who’s more concerned with micronutrients (like vitamins and minerals) than with calories or macronutrients (like protein andcarbohydrates). It’s indicative of Dr. Fuhrman’s overall approach to the science of food: If every calorie we eat is as nutrient-dense as possible, good health will follow. The family physician and former competitive figure skater has launched something of a movement in the health and fitness space, including three TV shows and several bestsellers, the most recent of which, “The End of Diabetes" The Eat to Live Plan to Prevent and Reverse Diabetes,” appeared on The New York Times Bestseller List. His most popular book, “Eat to Live: The Amazing Nutrient-Rich Program for Fast and Sustained Weight Loss,” has sold over a million copies, and Fuhrman’s ultimate goal is to curb the obesity epidemic with diets made up almost entirely of fruits and vegetables. It certainly can't hurt! 28. Chris Kresser, Sherlock Health Blogger, podcaster, and acupuncturist Chris Kresser is best known for his rigid skepticism of everything in the health industry: For this guy, anything is up for debate. He began his journey by taking nothing at face value, and his philosophy has resulted in a fascinating body of work that’s equal parts Eastern and Western, yoga and Paleo, herbs and integrative medicine. Kresser doesn’t advocate anything that’s not backed up with studies (what a greatist!) and his thorough, research-based methods have earned him enormous respect in the health and wellness industry. If you’ve ever wanted to hear about the benefits of acupuncture and Chinese medicine without any hippie B.S., Chris Kresser is the guy to talk to. This year, Kresser is out to help us burn fat, boost energy, and reverse disease with his new book, "Your Personal Paleo Code." 29. Tracy Anderson, Trainer to the Stars Anderson doesn’t focus her brand on bulging biceps or twig-thin thighs — she’s all about creating the graceful strength and poise of a dancer. She has her own gyms in London, New York, and Los Angeles, and is also known for her line of workout DVDs and nutrition programs that can be customized for almost every kind of body type. But Anderson is probably most famous for training nearly every big name in Hollywood, including Madonna, Jennifer Lopez, and Gisele Bundchen. In 2013, she created Kim Kardashian’s post-pregnancy workout and teamed up with Gwyneth Paltrow to launch a webseries entitled “The Restart Project,” which is about women who have overcome adversity by improving their health and fitness. 30. Richard Simmons, Archduke of Aerobics The undisputed king of aerobics videos and sequined tank tops, Richard Simmons is one of the first fitness personalities to be known for… well, his personality. Eccentric and energetic (energentric?), Simmons injected humor and inclusiveness into an industry populated by self-serious bodybuilders, and since his spandex-clad debut in the 80s, he’s even expanded into political activism. Simmons worked tirelessly to include a physical education component in the No Child Left Behind Act, and openly expressed frustration during the recent government shutdown (who didn’t?). In 2013, Simmons worked harder than ever, participating in Swim For Relief (which benefitted Hurricane Sandy victims) and even released his own single, “Hair Do.” 31. Wayne Dyer, The Father of Motivation Often called “the father of motivation,” Dyer has written over 30 books to help people cure their neuroses, think more positively, and become more self-reliant. Having worked as a professor, author, and speaker, Dyer has an intimate knowledge of what makes people tick, and weaves spiritual and religious themes into much of his writing. He’s been called “New Age,” but Dyer just wants people to shed their guilt and explore their “higher self.” Whatever you think of his approach, it’s worked for a lot of people, and his PBS show, “Wishes Fulfilled,” is pretty popular on YouTube. 32. Tom Venuto, Master Fat Burner This is no muscle-bound goon! The only way to be as lean and muscular as Tom Venuto is to have a profound understanding of the complex science that underpins nutrition and physiology. With a degree in exercise science, hundreds of published articles, and certifications from the American College of Sports Medicine (ACSM) and the National Strength and Conditioning Association (NSCA), Venuto is the thinking man’s bodybuilder. He works as a trainer, nutrition consultant, and fitness model, but he’s best known for his book, “Burn the Fat, Feed the Muscle,” which also spawned a supportive online community, Burn the Fat Inner Circle. For those interested in the “why” behind bodybuilders’ results, this is the man to check out. 33. Dr. Yoni Freedhoff, The Weight Doctor Yoni Freedhoff is not afraid to speak his mind. His frank (and thoroughly researched) views on private and governmental health practices have made him something of a celebrity in the blogging world. Though he works full time as the medical director of Ottawa's Bariatric Medical Institute, it’s hard to go a week without seeing a Freedhoff op-ed in one media outlet or another (including Greatist!), and his personable, engaging style has resulted in an impressive following, an award-winning blog (Weighty Matters), and a tremendous platform from which he works to change the industry for the better. His book, "The Diet Fix: Why Diets Fail and How to Make Yours Work," will be released in March.