A new study proves that the old adage "use it or lose it" is definitely true when it comes to fitness.
After just two weeks of sedentary behavior, formerly fit people had:
- A decline in heart and lung health
- Increased waist circumference
- Greater body fat and liver fat
- Higher levels of insulin resistance
"The study showed that two weeks of reduced physical activity -- from approximately 10,000 steps per day down to 1,500 per day -- caused changes in health markers that are associated with type 2 diabetes and cardiovascular disease," study author Kelly Bowden Davies says. Bowden Davies is a lecturer at Newcastle University and the University of Liverpool in the United Kingdom.
But the good news from the study is that the body seems to quickly bounce back once you start moving again.
READ: The Netflix Workout: Easy Exercises For Couch Potatoes
"It's important to note that when people resumed their normal activity levels after this period, the negative health changes were reversed," she says.
The researchers recruited 28 healthy, regularly active adults. Eighteen were women. The average age of the study volunteers was 32. Their average body mass index (BMI) -- a rough measure of body fat based on height and weight measurements -- was just over 24. A BMI under 24.9 is considered normal weight.
The study volunteers had been quite active, normally clocking about 10,000 steps daily. Bowden Davies says most of this was just from daily activity, rather than structured exercise. They usually participate in no more than two hours of structured exercise weekly.
The researchers asked the volunteers to cut their activity drastically. They dropped an average of just over 100 minutes a day, the researchers share.
After two weeks of couch potato life, the study volunteers underwent a battery of testing. These results were compared to findings measured when the study started.
Bowden Davies says cardiorespiratory fitness levels dropped by 4% in just two weeks.
READ: ‘Couch Potatoes’ May Face Higher Risk of Kidney & Bladder Cancers
Waist circumference rose by nearly one-third of an inch. Liver fat increased by 0.2%. Total body fat went up by 0.5%. Insulin resistance increased and triglyceride (a type of blood fat) levels went up slightly.
Fourteen days after resuming activity, these measures all bounced back, the investigators found.
"Even subtle increases of inactivity can have a positive effect on health. Moving more and breaking up sedentary activity is encouraged," Bowden Davies adds.
Dr. John Osborne, an American Heart Association spokesman, says this was a very interesting, and somewhat surprising, study. The findings validate the advice he gives his patients. "If you can be a shark or a turtle, be a shark -- always moving. This study showed you can lose the benefits of exercise very quickly, but the good news is
that when they became sharks again, all the benefits came right back."
Another expert who reviewed the study, Dr. Edmund Giegerich, chief of endocrinology and vice chairman of medicine at New York-Presbyterian Brooklyn Methodist Hospital in New York City, was also somewhat surprised by the magnitude of changes that happened in just two weeks.
Giegerich says the study confirms how important it is to stay active.
"Going from being sedentary to more active can help a great deal in preventing the onset of type 2 diabetes. Just try to be more active. You'll feel better, and if you're trying to lose weight, it can help a little. You don't have to run a marathon. Walking is fine. Just get up and get moving," he advises.
READ: Get Better Results From Your Workouts With One Change
Both experts point out that the study was small, and in a larger group, the findings might be different. The study was also only done for a short period of time.
Bowden Davies, Osborne, and Giegerich all suspect that if people who are at a lower fitness level stop almost all of their activity that the results might even be worse.
Learn more about the benefits of exercise from the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.