Human bodies are not machines. Computers and cars are at their best when they first leave the factory floor. They continue to break down and fall apart the longer they are used. Human bodies are alive. They are constantly rebuilding, renewing, redirecting. Your body is in a constant state of creation and destruction. Nothing stays the same from second to second.

       Look at your face in the mirror. Within two weeks, all the skin cells have been replaced. You literally have a new face. The cells lining your gut are gone and replaced within five days. Beyond the DNA in a few cell forms, like brain cells and lens cells, a large part of you has been replaced within the year.

       How do you keep that rebuilding process going? How do you prevent heart disease and stroke, diabetes and cancer? How do you keep your brain alive and active and fight off Alzheimer’s disease and Parkinsonism? You move. The human body is built to move. We are exquisitely designed to walk, stroll, dance, bend and turn, run and dance, to constantly redesign our bodies and minds through use.

       Humans have been on the planet for about two to two and a half million years. Until the last 12,000 years or so, we spent all that time as hunter gatherers. Though few remain, present day hunter gatherer societies are in motion through much of the day. Many walk about eight to 20 miles a day, though not all at once. Many hunter gatherer societies eat, move, and rest, the pattern followed by most mammals and most human children.

       This sequence of Food-Activity-Rest, or going FAR, is the way of life generally used by the longest lived populations on earth. For many of us it is a simple plan for living a long and healthy life. We appear designed to live this way — to eat, move and rest. As part of FAR, how much movement is required?What is exercise, and how much do I need?

       Exercise should be defined as use of any our muscles beyond our groups of smooth muscle that line our gut, mucous membranes and internal organs. From the standpoint of long-term health, all physical activity takes up energy and potentially revs up metabolism. Even standing takes up 25% more calories than sitting, a fact which can be used to increase alertness at work.

       How much exercise depends on your goal. But if it’s increasing your lifespan, holding off diabetes, Alzheimer’s disease, Parkinson’s disease, stroke, and heart attack, the amount is surprisingly little — about an hour total of our waking allotment of 16-17 hours a day.An hour a day comes from the number usually cited by researchers as increasing overall longevity — 2,500-3,000 calories a week. This sounds like much more “exercise” than it is. Getting out of bed and getting to the kitchen and car take up 200-300 calories. And walking can produce about 400 hour calories of energy used per hour (it depends on your size — the bigger you are, the more calories you expend.)Walking an hour a day is difficult for people until they realize a few facts:

1. It doesn’t have to be done all at once. You can walk seconds, minutes, or if your prefer, hours at a time.
   
   
2. Considering that your body seems well designed as a walking machine, spending about 6% of your waking hours doing something physical is actually a small amount.
   
   
3. Virtually any kind of physical activity, including fidgeting, uses energy calories.
   
   
4. Activity helps at whatever age you try it, especially when you’re elder.
   
   
5. Movement is the key to fighting the epidemics of obesity, diabetes, and dementia.Recent studies have shocked even veteran researchers. Parkinsonism was reduced 50-60% by people doing relatively minimal exercise during their forties and fifties. Meanwhile, it appears that Alzheimer’s disease is a two-hit phenomenon, requiring both Alzheimer’s cellular changes in brain cells and clogged brain arteries. Walking and eating sensibly, as occurs with those who follow FAR, may prevent Alzheimer’s clinical manifestation even in those who have brain cells infested with changes of the disease.
   
   And walking or moving a total of 2,500-3,000 calories a week seems the best way to lose weight — in combination with eating right and getting enough rest. One recent study of obese people who averaged a little less than one hour’s walking or movement per day found body weight loss of over 13% of weight after a single year. The National Weight Loss Registry, which follows those who kept off 30 pounds for three years or more, found the average increase in exercise was 2800 calories a week, about the same amount found to maximally increase lifespan.

What To Do

       The simplest answer for most of us to is move during ordinary activities. If tied to a desk, reach down for a pencil. Take a bathroom break and use a few minutes to go up and down stairs. Walk to restaurants rather than drive to them.

       View yourself as a transport vehicle. With time you should be able to walk places within a quarter-mile radius, then a half mile, perhaps a mile or more. Walking is patriotic. Walking doesn’t burn foreign oil. You don’t worsen global warming. Walking helps you rebuild and renew your body, improving your mood and healthiness. You needn’t walk alone. Take your friends, family or coworkers for a stroll. It helps increase social support and get yourself out of your house and workplace. Using FAR with socializing helps keep down weight and prevent diabetes or obesity.

       Though it’s fun, there are many other things to do besides walking. You can swim or bike, hike or row. You can do yardwork, push a lawnmower, rearrange bookshelves. You can do standing pushups at your desk, visit coworkers and talk to them face-to-face rather than by telephone, go over to another department in your building or discover a new restaurant. And all the time you’re rebuilding and reshaping your body and keeping it whole.

       All you have to lose is weight and waistline, while gaining pleasure and perhaps years of life. Knowing how to use your human design can help you in many parts of your life.

Dr. Matthew Edlund, M.D., M.O.H., director of The Center for Circadian Medicine, is an expert on applied public health, sleep medicine and psychiatry. A former professor at Brown and University of Texas medical schools, he can be reached via email to DocME@DoctorEdlund.com. And CLICK HERE to subscribe to our new Fitcast, via the iTunes Store.