Doylestown cardiologist David L. Smith, MD, holds up three test tubes filled with a white fatty substance and announces, “think of this as a Big Mac.”

Dr. Smith is talking to students at a local middle school about how today’s lifestyle and poor eating habits are causing heart disease.

“You are the first generation who may not live as long as your parents,” he states, “unless we can get you to change your eating, exercise and general health habits. Some of you will live to be 100 years old; some of you will have a heart attack by age 45.”

Dr. Smith stresses healthy eating during his talks. “The greatest health problem today is obesity,” he says.

“Twenty percent of today’s teens are overweight and while society’s habit of eating fast food numerous times a week contributes, so does lack of exercise.”

Dr. Smith produces a chart showing how many calories we burn through exercise. “Let’s do some math,” he encourages. “If you’re a swimmer, you burn 300 calories doing 30 laps in 30 minutes. If you get a small order of French fries on the way home from swimming, you eat or add back 200 calories.

“If I can convince just one young person to live a healthy life and avoid heart disease, my mission is accomplished,” he says.