How to Change Your Biological Age

by Dr. William J. Evans, PHD

William J. Evans Professor, Chemistry

     Gray hair, wrinkled skin, growing flabbiness, loss of vitality and reduced resistance to injury and disease...  to most Americans, these are harbingers of old age, unwelcome but inevitable milestones along a path that leads inexorably to the grave.  In fact, recent research suggests something quite different -- that the body's gradual decline stems not from the passing of years but from the combined effects of inactivity and poor nutrition.  So no matter what your present health status or your chronological age, regular exercise and improved eating habits will lower your biological age.   

     The Benefits:  Reduced body fat, increased muscle mass, strength increases of 200% to 300%, increases in aerobic capacity of 20% or more, and reduced risk of heart disease, diabetes, osteoporosis and other age-related ailments.  Your goal should not be to become immortal, but to remain healthy and vigorous for as long as possible and to compress the inevitable period of decline preceding death from several years into a few weeks or months.

      To gage your biological age, forget how many birthdays you've marked.  Instead, consider how you stack up in terms of the 10 key 'biomarkers' identified by our lab...

-         Muscle mass. As Americans move from adolescence into old age, we lose almost seven pounds of lean body mass each decade, a rate that accelerates after age 45.

     Reduced muscle mass leads not only to reduced strength, but also to an increased risk of heart disease and diabetes, reduced aerobic capacity and a slower metabolism (which promotes gain of fat) all because of bad habits like driving instead of walking or riding a bike, taking elevators rather than stairs, and because we're all too willing to let younger friends and relatives do chores we could do ourselves.

     Good news:  Those who remain physically active lose little muscle tissue as they age.  All it takes is 20 to 30 minutes of aerobic exercise two or three times weekly.

- Strength. Between the ages of 20 and 70, the average American loses about 30% of his muscle cells including a large proportion of 'fast- twitch' cells needed for sprinting and other high-exertion exercise.

      Unchecked, this loss of muscle leads eventually to sarcopenia, the severe, debilitating weakness that makes independent living impossible.

     Good news: While we cannot prevent loss of muscle cells, a weight-lifting regimen will compensate by boosting the size and strength of the cells that remain.

     Essential:  Ten repetitions of 10 lifts with a weight that should leave your muscles completely fatigued.  If not, add more weight.

-         Metabolic rate. Because more energy is needed to maintain muscle than fat, the less muscle tissue in your body, the slower your metabolism and the fewer calories you must consume to maintain ideal body weight.  Beginning at age 20, the average person's metabolic rate drops about 2% per decade.  Thus the average 70 year old needs 500 fewer calories a day than the average 25 year old.

     Problem: Many middle-aged Americans continue eating as if they were 20. 

     Eventual result:  Obesity. To fight fat, eat fewer calories and get enough exercise to maintain your muscle mass.

-         Body fat percentage.  In most cases, advancing age brings not only muscle loss but fat gain. Even if our weight  (as measured by a scale) changes little, the ratio of fat to lean in our bodies can rise markedly over the years.

     The body of the average 25-year-old woman is 25% fat, for example, while the average 65-year-old woman is about 43% fat. For men, the numbers rise from 18% fat at age 25 to 38% at 65.

     Danger:  Excessive fat leads to chronic disease and premature death. 

     Especially dangerous:  Fat around the waist. It's far more unhealthy than fat on the buttocks or thighs. 

     To lose fat and gain muscle:  Combine a low-fat diet with regular exercise.

-         Aerobic capacity. To gauge fitness, doctors often measure the body's ability to process oxygen during exercise. The greater this aerobic capacity, the faster oxygen is pumped throughout the body and the fitter the individual.  Like other biomarkers, aerobic capacity often declines with age.  Typically, by age 65 it is 30% to 40% below its level in young adulthood.

     Good news: Regular aerobic exercise -- the kind that causes huffing and puffing -- will raise your aerobic capacity no matter what your present age. The longer and harder your workouts, the greater the benefit.

-         Blood-sugar tolerance. For most Americans, aging brings about a gradual decline in the body's ability to metabolize blood sugar (glucose). So common is this problem that by age 70, 20% of men and 30% of women are at increased risk of diabetes, a potential  killer.

     At special risk for problems:  The overweight, the sedentary and those who eat a fatty diet.

     Good news: A low-fat, high-fiber diet, combined with regular exercise, will cut your diabetes risk.  Be sure to include both strength-building and aerobic exercise in your routine.

-         Cholesterol ratio. As most of us already know, a high cholesterol level boosts your risk of heart disease. But total cholesterol isn't the only thing that counts.

     Very important: The ratio of total cholesterol to HDL (good) cholesterol. For older people, the ideal ratio is 4.5 or lower. A person whose total cholesterol is 200 and whose HDL is 50, for example, has a ratio of 200/50, or 4.0.

     To lower your ratio:  Stop smoking, lose weight, reduce your intake of fatty, cholesterol-rich foods (especially animal products) and exercise regularly.  Exercise is the only way to boost HDL levels.

-         Blood pressure. In many parts of the world, advancing age brings little if any change in blood pressure. In the US, however, where older people tend to be both overweight and sedentary, blood pressure does rise with age, often spiraling far above the maximum "safe" level of 145/80.

     To keep pressure in check:  Stay slim, don't smoke, get regular exercise and limit your consumption of fat, salt and alcohol.  If these steps fail, pressure-lowering drugs may be necessary.

-         Bone density. As we age, our skeletons slowly become weaker and more brittle. While some mineral loss is inevitable, the severe and potentially deadly condition known as osteoporosis is not.

     Prevention: Although consuming at least 800 milligrams of calcium a day will retard the loss of bone, that alone rarely does the trick. 

     Also needed: Weight-bearing exercise, such as walking, running or cycling.

     Not helpful: Swimming and other forms of exercise that do not subject the long bones to the stress of gravity.