Scientists on both sides of the Atlantic have made the discovery through two quite different long-term studies on almost 5000 people.
And the good news is that reaping the benefits is as simple as accepting their findings.
Questions about health and fitness have always plagued us, and mens fitness and health, health and fitness magazine articles and newspaper stories have merely muddled the reality and complicated the process involved.
These two studies give objective scientific clarity to the benefits of fitness and nutrition on health.
From King's College London we get the news that daily exercise helps the body's cells to stay youthful because it lengthens structures called telomeres, which protect the DNA on our chromosomes.
And from the 20-year observational study conducted in conjunction with the Coronary Artery Risk Development in Young Adults (CARDIA) Fitness Study in the US, comes the finding that weight gain and heart disease are caused by substantial declines in physical fitness and activity levels as we reach middle age.
Put those together, and we find a recommendation to raise a sweat regularly. And smile our way into a healthy older age.
Vitally Important To Your Health
In the past 30 years, the prevalence of obesity among adults ages 20 to 74 has increased from 15 percent to nearly 33 percent, according to the Center for Disease Control and Prevention. So the findings are vitally important.
The British study claims that exercise may hold the key to youth. It shows that people who keep fit are up to nine years biologically younger than those who do not. In fact, it says the findings are the first to show in humans how keeping fit affects the ageing process.
The study of 2401 twins found that a sedentary lifestyle raises the risk of a range of problems, from heart disease to cancer, and appears to play a key role in the ageing process.
Many studies have shown that telomeres get shorter over time, suggesting the cells are ageing or dying.
The study, which extracted a DNA sample from volunteers, found people who exercised more each week had longer telomeres.
Really Work Up A Sweat
"It is not just walking around the block. It is really working up a sweat," said Tim Spector, a genetic epidemiologist who led the study.
The study found people who exercised vigorously for three hours each week had longer telomeres and were biologically nine years younger than people who did less than 15 minutes.
Spector's team, who also adjusted for body weight, smoking, economic status and physical activity at work, also said moderate exercise for 1 1/2 hours each week provided a four-year advantage.
"We are making a logical next step to say people who have shorter telomeres are more prone to age-related diseases," he said.
"We think it is because these cells are auto-destructing and the ageing process is sped up."
The American study followed 2,289 men and women, ages 18 to 30, over a 20-year period at four research sites across the US.
Study participants, comprised of both Caucasians and African Americans, saw their physical fitness levels decline by an average 28 percent, their weight increase by an average 20 percent, and their self-reported physical activity drop by an average 18 percent over a 20 year-period (1985-86 to 2005-06).
Control Your Physical Activity
"While aging is something we have no control over, most of us do have the ability to control how physically active we remain as we get older," said Stephen Sidney, MD, MPH, the study's principal investigator
"This study shows the importance of staying physically active throughout our lives and how we can better influence our fitness levels, and consequently, better manage our weight."
Fitness level declines in study participants were inversely associated with weight gains, and directly associated with changes in physical activity scores.
"We know that low physical fitness levels put people at greater risk of cardiovascular disease and related deaths," said Dr. Sidney. "Staying physically active is also a great way to stave off obesity."
Them's the facts, folks. How are you going to drink from the fitness nutrition health fountain of youth they've unveiled?