The physician and best-selling author of "Body for Life for Women" talks stress, the scale and the surprisingly simple ways women can improve their health. Pamela Peeke, M.D., is the medical adviser for the National Women's Health Resource Center.

Lifetime: Most women say they have all the information they need to maintain a healthy weight — yet two-thirds are overweight or obese. What's keeping them from taking action?
Dr. Peeke: I think there are a few things at hand. First, women are hardwired to be caregivers. They wake up in the morning with the best of intentions — but one phone call from a good friend going through a divorce and the next thing you know, there goes the trip to the gym! Getting past this habit requires teaching yourself to develop limits and boundaries. You have to tell yourself, "It's OK to take care of me — I deserve this."

I think it takes a healthy focus too; you need to want to lose weight or keep it off for the right reasons. Often, women are changing their lifestyle just to fit into a pair of jeans in a subzero size — rather than, say, wanting to be around for their children when they're older. That just doesn't work. It's so important to focus on the deeper and more meaningful reasons to take care of yourself.

The other big factor is perfectionism — thinking that if you can't do something the "perfect way," you're not going to do it at all. For example, if you don't take the perfect walk at the perfect time with the perfect exercise buddies, it's not going to happen. I think perfection is paralysis. You have to learn to take those small, imperfect steps or you'll never make progress toward adopting a healthier lifestyle.

Lifetime: Do you have to be thin to be healthy? How does being overweight affect your health?
Peeke: I hate the word thin — you can be thin and in terrible shape and unable to even run up the stairs to call 911. Women should throw out their scales and go buy a body-fat analyzer that measures body fat and weight, because body composition is a far better measure of health. By body composition, I mean how much fat you have and where it's located. Regardless of your age, you want your body mass index to be in the twenties. That's a healthy range.

Waist circumference is also very important. All it takes is a tape measure for you to know if you're in trouble. If your waist measures less than 35 inches, it's a very good thing. If it's more, it's a very bad thing, because it means you have too much belly fat. And the fat deep inside the stomach area doubles and even triples your rate of heart disease, diabetes and cancer, in part because it keeps your vital organs, such as your liver, from being able to function correctly.

Lifetime: How does stress impact health? And how can women get their stress levels under control?
Peeke: Women tend to overeat to deal with stress. It's partially because we have lower levels of the feel-good brain chemical serotonin, so we seek rich, high-calorie and/or high-fat foods — think a pint of Ben & Jerry's — to increase those levels. In addition to food, many women turn to alcohol, cigarettes and drugs to cope with stress, which isn't healthy. Stress is also a problem because it can screw up our relationships and cause us to withdraw socially.

Reducing stress means establishing boundaries and learning how to say no elegantly. Here's a great one-liner that I teach women: "Why, thank you, but that doesn't work for me." You have to have the courage to say no. Practice in the mirror if you have to! Most women have a tsunami of guilt; every time they actually try to do something assertive, they think, What will that person think, what if I hurt them? You simply cannot operate that way. You're being real by doing what you actually want to do, and people will respect you much more than when you act like a welcome mat.

It's also important to identify the main stressor in your life, whether it's your commute, never having enough time, a problematic boss, etc. Then, begin to work around that stressor, getting rid of it if you can and coping with how you feel about it if you can't. Physical activity is an incredibly powerful way to reduce negative stress-related feelings; it increases positive brain chemicals such as beta-endorphins and serotonin. Eating well is important too. The less trash you put in your body, the less stressed your body will be and the more energy you'll have.

Lifetime: What do you do when your family members are resistant to leading a healthier lifestyle?
Peeke: Family members will always be resistant — it's a miracle when everyone's on the same page! You have to be a leader and yet take your own journey. If your family members want to change their lifestyle for the better too, that's great. But if they don't, don't police them and don't nag them. For example, if someone joins you on your walk, click your heels with happiness. If no one wants to walk with you, walk by yourself. And remember, people may change at varying levels — your husband may exercise with you but still eat junk food. That's OK; that's his journey. All you can do is set a good example through your own healthy behaviors.

Lifetime: What advice do you have for women who have lost weight then gained it back, or who have not been able to stick with a healthier lifestyle?
Peeke: Vince Lombardi, the great coach, once said: "It's not the team who wants to win who wins. It's the team who wants to win and is willing to do the work who wins." You can really, really want to be slender and healthy — and who the heck doesn't? The question is, are you willing to change your schedule and make small steps to make it happen? If you are, then you will be able to do it — for good. Equally important, you have to remember that healthy living is not a onetime thing. Every single day — every single minute of your life — you have to strive to maintain a healthy lifestyle.