You hear a lot these days about healthy weight and "Body Mass Index" (BMI). This number indicates how much you weigh compared to your height. Although researchers have estimated what ranges of BMI they believe are healthy, underweight, and overweight, in truth, neither the number you see on your scale nor your BMI automatically show how healthy you are or how good you feel.

One person with a BMI above normal may be healthy and fit, while another at a normal BMI may be at high risk for disease. These differences are due to family history, lifestyle, and age, as well as fitness levels and other possible factors. So, if BMI is not a magic number, how can you more meaningfully assess your weight and health?

There are at least five "health indicators" -- factors that give clues to a person's health -- that are affected by body fat and physical fitness. You and your doctor can look at these indicators to check your current status and to monitor improvements in response to changes you may make in diet or exercise.

• Blood pressure: Excess body fat can increase blood pressure to harmful levels. Very high blood pressure requires medical treatment. Moderate weight loss and/or increased physical activity, however, can often manage borderline levels.

• Blood sugar and insulin levels: Excess body fat and low levels of physical activity can alter the body's use of sugars from food. Early in this process the body responds by producing increased insulin, a chemical that helps bring sugars into cells. High blood sugar and insulin levels can be an early sign of diabetes, a serious and potentially life-threatening disease. Increased activity and slight reductions in body fat can normalize sugar and insulin levels in individuals who are not yet diabetic.

• Blood cholesterol and triglyceride levels: High levels of body fat can lead to increased cholesterol and triglycerides (fats in the blood), which in turn increase risk of heart attack and stroke. If your cholesterol is higher than normal, reducing "saturated" and "hydrogenated" fat in the diet, while substituting "unsaturated" fats, whole grains, fruits and vegetables, can help significantly. Physical activity can reduce both cholesterol and triglycerides.

• Physical fitness: Increased fitness has been shown to decrease chronic disease, regardless of BMI. Your doctor can evaluate your fitness level using a treadmill and heart monitor. You can test your endurance to walk up a hill or stairs. Most people can improve their fitness level by slowly and steadily increasing physical activity and exercise. Moderate strength training, in a gym or at home, provides substantial added benefits. (If you are currently inactive, consult your doctor before starting an exercise program.)

• Where's your body fat? Research shows that people who store their excess body fat at their waist are more likely to develop diabetes, regardless of their BMI. This fat can also strain the heart and disturb sleep. The most successful method to reduce your waistline is slow weight loss resulting from increased physical activity -- such weight loss burns fat instead of muscle.

Unlike BMI, these five health indicators directly relate to disease risk, comfort, and enjoyment of life.