We've seen it on the news, the covers of best-selling novels, and even on the big screen. Americans are getting bigger and more unhealthy day by day. Over a third of American adults are considered obese, and it's estimated that up to one in three adults will suffer from diabetes by the year 2050. (In 2010, it affected one in 10 U.S. adults.) And many of these problems have been blamed on things like fast food, super-sized portions, and high levels of sugar in the foods available on store shelves.

So just what has to be done to turn this doom-train around? Maybe it's eating more local produce? Or improving school lunches? Or campaigning for better regulations in the food industry? Whatever ends up being the answer, here are our 15 favorite health heroes who have devoted themselves to improving America's relationship with food.

1. Marion Nestle
Let's talk politics. Food Politics, that is. It's the name of Nestle's blog, where she writes about nutrition, biology, health policy, and food marketing. She's published several books discussing the importance of our food sources, including Food Politics: How the Food Industry Influences Nutrition and Health and Safe Food. Her research has made waves in the world of food politics, including on topics like the scientific and socioeconomic influences on food choices, obesity, and food safety, and she emphasizes the role of food marketing in the health of our country. No relation to the Crunch bar. (Photo: www.foodpolitics.com) — SL

2. Michael Pollan
Food for thought is this guy's specialty. Michael Pollan's the author of bestsellers like The Omnivore's Dilemma and, most recently, Food Rules: An Eater's Manual. One of the leading activists for changes in the food industry, he's never shy about sharing his (often controversial) opinions on food, agriculture, and health. (Photo: Ken Light)— SL

3. Ann Cooper
"School lunch" usually brings back memories of processed food-like substance — I'm still scarred by "pizza-burgers." Chef Ann Cooper, better known also known as “Chef Ann” or the “Renegade Lunch Lady,” has one mission — to change the way we feed kids in our school. She's working with schools to reasonably budget for healthy food and pushing for school lunch to become a part of the legislative conversation. (Photo: Kristen Boyer) — KK

4. Sam Kass
This Chicago native isn't JUST the first family's personal chef — he plays a huge role in first lady Michelle Obama's “Lets Move!” campaign, too, starting with the garden on the White House's South Lawn. Kass has worked on everything from child nutrition legislation to how to fund school lunch programs, and the best ways to fight childhood obesity. (Photo: www.obamafoodorama.blogspot.com) — KM

5. Alice Waters
In terms of the “slow food” movement in America, Alice Waters and her restaurant Chez Panisse started it all. Waters and her iconic San Francisco restaurant helped launch the organic craze by serving only healthy, local, high-quality ingredients. Waters, an organic food advocate and activist, has expanded her mission of using a few amazing ingredients cooked to perfection by creating the Chez Panisse Foundation and the Edible Schoolyard, two initiatives designed to bring healthy food and produce into classrooms across America. (Photo: www.chezpanisse.com) — ZS

6. Robyn O'Brien
After working as a food industry analyst, Robyn O’Brien decided to switch gears to become an author and public speaker about the issues that matter to her most — ensuring the food we eat (and feed our children) is safe and healthy, and making sure the food industry understands that necessity, too. Her first book, The Unhealthy Truth, discusses the ties between American food, government, and culture, and the importance of  cleaning up the food system in our country. O’Brien also founded AllergyKids to help children suffering from food allergies, autism, ADHD, and asthma, and to address the role that food additives play in our health. This is one mother (of four!) who’s taken the health of her family as inspiration to help millions of others! (Photo: www.robynobrien.com) — KM

7. Jamie Oliver
Starting with his ABC reality show Jamie Oliver's Food Revolution back in 2010, this British chef started the "revamp America's school kitchens" fire. Even after filming ended, the Food Revolution campaign has been dedicated to improving school lunches across the country. He's won countless awards for his efforts, and although his defeat by the bureaucracy of the school system was well documented on the show, his efforts made lasting waves that have continued to inspire others to make a difference since. (Photo: www.jamieoliver.com) — KM

8. Mike Bloomberg
Mike Bloomberg isn't afraid to make waves in the name of public health, and other cities take note. As NYC's mayor, he's tackled smoking in public and banned the use of trans fats in many of the city's restaurants. Next up? Sugary drinks — he recently proposed a (very controversial) ban on the sale of large sodas. Now, for the rest of the country! (Photo: www.nyc.gov) — KK

9. Melissa Graham
She’s a sustainable cook, locavore blogger, and “head spear” at Purple Asparagus, a Chicago-based organization dedicated to teaching people about healthful eating. Among the non-profit’s core goals: Changing the way our children, and by extension, our families and communities, relate to food and all things associated with it. (Photo: www.purpleasparagus.com) — JS

10. Mark Bittman
New York Times writer and author of How to Cook Everything, Bittman talks all things food, notably the connections between food, health, and the environment. And while he claims he's "not a chef," his recipes for lemon cheesecake and salmon fillets are simple to follow and decidedly delicious (and nothin’ but natural). (Photo: markbittman.com) — LS

11. Eric Schlosser
Not so fast, fast food. Investigative journalist Eric Schlosser took out his magnifying glass to uncover the harmful influence of the fast food industry in his New York Times bestseller Fast Food Nation (and the accompanying film). Ten years has passed since it's release, and since then a healthy food movement has swept the nation, tacking subjects from food safety and the obesity epidemic, to trans-fats and supersized portions. — LS

12. Gary Taubes
Science writer Gary Taubes has tackled almost every major debate in the research space, but its his most recent crusade that's defining his career. His 2007 book Good Calories, Bad Calories attacks long-held notions about how fat consumption affects the human body, a discussion that put Taubes at the forefront of debate that continues today. While Taubes has his fair share of critics, his writing has inspired thousands to become more conscious of what they eat — and what they thought they new about food. (Photo: www.garytaubes.com) —DT

13. Dr. Catherine Shanahan
An apple a day won’t keep this doctor away. A board-certified Family Physician, Dr. Cate Shanahan is a trained biochemist and geneticist. Luckily for us, she doesn’t keep all her knowledge to herself — she shares her tips on better shopping, cooking, and healthy eating habits on her website. This author of Deep Nutrition and Food Rules is up-to-date with the current trends in science and medicine, shedding light on misconceptions and scientific validity and voicing her opinion on important health matters. (Photo: www.drcate.com) — AW

14. Robert Kenner
It's one thing to believe that we need better standards for meat and produce production. It's quite another to create an impassioned documentary to fight for a healthier tomorrow. Robert Kenner took on that mission, creating the 2008 documentary "Food, Inc.," which examines and critiques the impact of corporate (read: mass-produced) farming in America and how volume inevitably dilutes quality. "Food, Inc." helped spur nationwide debates about how business affects agriculture, and made Americans rethink just what we put in our mouths every day. Kenner didn't stop there, touring the country to speak about his findings and improve the quality of food in America. (Photo: www.documentary.org) — ZS

15. Sung E Bai
This local-food pioneer spent 25 years taking on economic injustices and immigrant rights. After enrolling her daughter in a daycare that serves children from low-income households and being dissatisfied with the meals provided, she’s now passionate about justice. Bai pushed to make healthy food more accessible for working people. Now through Slow Food USA, a global grassroots network that believes food and farming are at the root of health, she’s working towards improving local food systems. (Photo: Slow Food USA) — NM

Anyone you think is missing from this list? Join the conversation in the comments below!