What do Coloradans know about fitness that you don't?

Known as the slimmest state since 2010, gorgeous Colorado boasts the lowest rate of obesity in all of America. According to the Gallup-Healthways Well-Being Index, Colorado residents were the least likely in the nation to be obese in 2012. And Colorado is the only state where less than 20 percent of adults are obese. But what makes those in Colorado different than the rest of us when it comes to managing their weight?

To uncover the mystery, James Hill, founding executive director of the Anschutz Health and Wellness Center at the University of Colorado, and Holly Wyatt, a physician and researcher at the center, studied the behaviors of lean people who live in Colorado. They also examined the habits of patients in their weight loss clinic. Based on their findings, they created a program based on what they consider to be the six key factors that can help all of America create a healthy, lean lifestyle in their new book, "The State of Slim: Fix Your Metabolism and Drop 20 Pounds in 8 Weeks on the Colorado Diet."

[Read: Why We're So Fat: What's Behind the Latest Obesity Rates.]

I had the opportunity to interview the authors via email. Their responses have been edited.

In State of Slim, you say dropping pounds is only part of the picture - and that keeping weight off is a different challenge than losing weight and requires a different strategy. Can you elaborate?

Losing weight only requires a short-term strategy while maintaining weight requires a long-term strategy. Losing weight is most frequently accomplished by eating less - of anything. This is the way all diets work for weight loss. Whether you're not eating fat or carbs or sugar, the result is that you lose weight. The problem is that you can't maintain food restriction forever because you get hungry. You can do just about anything for a few weeks in order to lose weight, but keeping weight off is a long-term process.

While diet is a big driver of losing weight, physical activity is the major driver of keeping it off. It does this in three ways: First, it increases your energy expenditure so you can now eat a reasonable amount of food without gaining weight. Second (we explain this in the book), it fixes an inflexible metabolism, which means your body is now working with you - not against you - to maintain a healthy weight. Third, it better couples your appetite with your metabolism.

The best long-term eating strategy is not food restriction but eating smarter. Losing weight can occur with temporary behaviors, while keeping weight off requires the establishment of new habits, routines and rituals. This takes time but is important for long-term success.

In the book, you say that following a Colorado lifestyle creates a 'Mile-High Metabolism.' What does this mean, and how did you come up with this concept?

We use the term 'Mile-High Metabolism' to describe a metabolism that is flexible and working the way it was meant to work. When you quit moving, your metabolism becomes inflexible and sluggish when switching between fat and carbohydrate for a fuel source. The result is a tendency to store rather than burn fat and to overeat. This leads to weight gain and obesity. If you don't fix your metabolism while you are losing weight, you risk regaining that weight. You can't fix your metabolism with losing weight alone - you have to move.

So many people embark on weight loss but fail because they don't mentally or otherwise set themselves up for success. You say the key to weight-loss success is in the 'Colorado mind-set.' Can you explain what that means?

To develop the 'Colorado mind-set,' people need to:

-- Expect success: Having a positive attitude is important. If you believe it, you will see it.

-- Find your motivation: It is important to get in touch with your purpose - what you want to accomplish with your life. If you connect your lifestyle with your purpose, you will find motivation to stick with a healthy lifestyle, even months after you have lost the weight.

-- Create a healthy environment: Make sure your physical environment is supportive of your new lifestyle. Don't keep food in the house that is a problem for you. Make sure you have healthy snacks on hand. Make sure you have a place to walk near your house or workplace. Also, create a healthy social environment. Your behaviors are influenced by the people you surround yourself with. Find ways to spend time with people who value the behaviors that you want to maintain.

[Read: Why a Fitness Funk is Contagious.]

In State of Slim, you say that being active nearly every day isn't optional. Your goal is for people to move 70 minutes a day, six days a week. For an active person, that may not sound like much. But for someone who is somewhat sedentary, 70 minutes may sound daunting. Can you explain how you got to that magic number and provide a few tips to help people work toward - and ultimately meet - that movement goal?

We find that the successful weight loss maintainers in the National Weight Control Registry average about one hour per day or 420 minutes per week of physical activity. We think giving people one day off each week will help, so we recommend 70 minutes per day for six days per week, which is 420 minutes weekly.

You can get to this level gradually. We start you out with only 10 minutes per day. You have a choice of getting all of your activity as planned activity (for example, a 70-minute workout or a 40-minute workout in the morning and a 30-minute workout in the afternoon), or you can get 35 minutes of planned activity and accumulate 7,000 steps per day. Either plan will help you get a Mile-High Metabolism. It is worth noting that a person who has never been obese needs less activity per day to prevent becoming obese.

Of course, diet is critical in helping people maintain a healthy metabolism. Can you briefly describe the three phases of your diet plan (and the rationale for each)?

Our goal is to match your diet to your metabolism. Most people start with an inflexible metabolism. Phase one, which lasts two weeks, is very structured and consists of lean protein, vegetables and a little fat. This is a diet that will ignite your body's fat burners. As you start moving and get your metabolism more flexible, we add in more carbohydrate and fat in phase two, which lasts six weeks. In phase three, you add in even more fat and carbohydrate and learn to eat smarter.

We have found that a moderately low-fat diet and paying attention to the quality of fat and carbohydrate is the best for people who are very physically active. Carbohydrate is the best fuel for your muscles. If you don't move, you don't need much carbohydrate. But when you start moving, carbohydrate provides your primary fuel.

[Read: How to Eat Before and After Exercising.]

Any final tips for long-term weight-loss maintenance?

Forget counting calories - this does not work. The essence of the plan is to monitor physical activity and weight and adjust food intake when needed. First, we recommend maintaining a daily physical activity goal and monitoring physical activity regularly. We also encourage people to weigh themselves - they can do this daily or every few days.

Because body weight fluctuates a little from day to day, we encourage people to have an acceptable weight range of a few pounds, for example. We encourage people to eat smarter - to learn about energy density and proper portion sizes. And when people find their weight on the scale exceeds their acceptable range, they should have a plan for modifying food intake such as redoing the first or second phase of the program for a week or two.

What is your biggest obstacle to losing weight and keeping it off?

[See: 11 Health Habits That Will Help You Live to 100.]

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

Elisa Zied, MS, RD, CDN, is the founder and president of Zied Health Communications, LLC, based in New York City. She's an award-winning registered dietitian and author of three books including Nutrition At Your Fingertips. A graduate of the University of Pennsylvania and New York University, Zied inspires others to make more healthful food choices and find enjoyable ways to "move it or lose it" through writing, public speaking, and media appearances. She writes the twice-weekly blog, The Scoop on Food, for Parents.com, and her new book, Younger Next Week, will be published by Harlequin Non Fiction on December 31, 2013. You can connect with her on Twitter and through her website: www.elisazied.com.