Normal weight. They were not overweight or obese, and maintained a body mass index below 25 (a threshold equivalent to 155 pounds for a 5-foot, 6-inch woman).
Nonsmoking. They had never been regular smokers, or they'd been smoke-free for at least 10 years.
Physically active. They got at least 20 minutes of heart-pounding, sweat-inducing exercise three or more times per week.
Healthy diet. They consumed a diet with lots of fiber, little trans fat, few refined or sugary carbohydrates, and a high ratio of good (polyunsaturated) to bad (saturated) fats.
Little to no drinking. They used alcohol in moderation, if at all -- two drinks or less a day for men, and one drink or less for women.
