While the total number of U.S. deaths from heart disease has declined in recent years, it has stayed the same for younger women.

This prompted researchers from Harvard and Indiana universities to look for lifestyle factors that could promote heart health. They analyzed 20 years of records from 89,000 women, aged 27 to 44, who participated in the Nurses' Health Study.

The investigators found six habits that define a healthy lifestyle.

No. 1 is not smoking.

No. 2 is having a normal BMI (or body mass index), a ratio of weight to height.

No. 3 is getting 2.5 hours or more of physical activity every week.

No. 4 is watching seven or fewer hours of TV a week.

No. 5 is eating a diet that scores in the top 40 percent of the Alternate Healthy Eating Index, a version of the national dietary guidelines for Americans based on foods shown to prevent serious illnesses.

Here's how.

Each day, eat:

• 5 or more servings of vegetables.
• 4 or more servings of whole fruit.
• 5 servings or 75 grams of whole grains.
• 1 serving of nuts and legumes.

In general:

• Eat two 4-ounce servings of fish, especially fatty fish, each week.
• Replace saturated fats with polyunsaturated fats.
• Eat less than one serving of red or processed meat a month.
• Eliminate sugar-sweetened drinks and fruit juices.
• Eat little or no trans fat.
• Eat little salt.

No. 6 is having no more than one alcoholic drink a day. One drink is 4 ounces of wine, 12 ounces of beer or 1.5 ounces of liquor.

This lifestyle also protects against diabetes, high blood pressure and high cholesterol.

Yet experts acknowledge the challenge of getting women to adopt it and hope that changing the nation's collective mindset from "preventing disease" to "promoting health" will help. They also stress the need to start kids on this healthy path because childhood is when lifelong habits are set.