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The Obesity Epidemic: Why Are So Many People Gaining Weight?
With the rates of obesity and being overweight rising at
alarming rates in most countries around the world, researchers
continue to search for explanations and solutions. Table of contents.
Every fitness professional knows that obesity
can result when people consume more energy than they expend. If calories in
exceed calories out, the energy difference is stored. The solution to
preventing obesity is simple: Eat less and exercise more. |
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Calories in: Too much food Studies suggest that people become overweight from the cumulative effect of overeating. Periods of overeating may be short or long. For example, some people gain about 1 pound per year, often during the holidays. While 1 pound does not sound like much, if it is gained each year, a great deal of extra weight will have accumulated after 30 years --enough to cause significant health problems. Some people may overeat to relieve emotional stress. These people may gain a significant amount of weight, more than 20 or 30pounds in a year, perhaps during an emotionally difficult time. Too much food may also be combined with a dramatic decrease in physical activity, such as when people face challenging times and stop exercising because they don't have enough time. Lack of sleep may also increase feelings of hunger and drive people to overeat. Many environmental factors encourage overeating. The U.S. is lucky to have an abundance of food that is relatively inexpensive. People must learn to make good food choices, and to be vigilant about saying no to more food when they have had enough to eat. Obesity researchers have proposed
that increased portion sizes are pushing people to overeat. If
extra food is on our plates, we tend to eat more than we should.
In many fast-food restaurants, the more we order, the better the
bargain. Portion sizes in other restaurants have increased over
the years as well. And individual food items, such as bottles
and cans of soft drinks, candy bars, muffins, bagels and
sandwiches, have grown larger during the past 30 years. |
Oddly enough, some studies suggest that, on average, people in
the U.S. are not eating many more calories than they did 30
years ago, when obesity rates were much lower. This has
perplexed scientists, and suggests that "too much food" may not
be the primary factor responsible for the startling rise in
obesity. Keep in mind, however, that the calculation of average
daily caloric intake is a fairly rough estimate, so numbers may
not be too accurate. Even just a little bit of overeating
sustained over time can result in an energy imbalance, and
consequent weight gain.
Calories out: Too little activity
Most researchers believe that declining daily activity levels
are at least partly to blame for the rising rates of obesity.
Daily life now requires less physical exertion than ever before.
Many jobs require little physical activity. People drive instead
of walk or ride a bike. And while labor-saving devices such as
garage door-openers, remote controls and elevators don't seem as
though they would really save that many calories, scientists
believe that this small decline in daily energy expenditure,
especially when coupled with a slight increase in caloric
intake, is enough to tip the scales in favor of a positive
energy balance, which translates into weight gain.
What about genetics? Some people are certainly more
predisposed than others to put on weight. But our population's genes have
not changed significantly in 30 years. Viruses replicating daily may see
change in a short period, but such is not the case for people. This does not
discount the enormous variation from person to person. But such variation
does not explain the rapid rise in obesity around the world.
Dietary change plus activity
Low levels of physical activity have been linked to many health problems. A
sedentary lifestyle is associated with increased risk of heart disease,
stroke, osteoporosis, some types of cancer and other negative health
effects, in addition to increased risk for obesity. Our bodies were made to
move, and regular physical activity is necessary for the maintenance of good
health. Fitness professionals know that physical activity is not some sort
of optional add-on to daily life; our bodies need activity just as they need
nutritious food. Without it, we have problems regulating blood sugar, blood
fats and blood pressure. We may also have problems regulating our appetites.
Countless anecdotal reports and some research have found that people have a
better sense of hunger and satiety (feeling like you have had enough to eat)
when they are exercising regularly.
Many people attempt to reverse unwanted weight gain by restricting food
intake. Theoretically, even if people are expending very few calories,
consuming even fewer calories should lead to a loss of body fat. And indeed,
weight loss does occur on low-calorie diets. This approach to obesity
prevention and treatment has not been very successful, however. A vast
majority of dieters regain the lost weight in a matter of months unless a
significant amount of physical activity is added to their daily lives.
Some people have even suggested that caloric restriction may be one of the
factors contributing to rising rates of obesity. Very-low-calorie diets are
poorly tolerated by most people. For some reason, and probably a good one,
our bodies and minds think we need to eat, and alarms seem to go off when we
try to sustain a low caloric intake. This is true even when our daily
activity levels are low. Therefore, we know that caloric restriction alone
is not the answer to the increasing number of people who are overweight and
obese. Good food choices and reasonable portion sizes must be coupled with
daily physical activity to prevent or treat obesity.
SOURCES
Hill, J.O., and E.L. Melanson. Overview of the determinants of overweight
and obesity: Current evidence and research issues. Medicine and Science in
Sports and Exercise 31 (11, Suppl):S515-S521, 1999.
Sizer, F., and E. Whitney. Nutrition: Concepts and Controversies. Belmont,
Calif.: Wadsworth/Thompson Learning, 2000.
Barbara A. Brehm, Ed.D., is professor of exercise and sport studies at Smith
College, Northampton, Mass.
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Many people with special needs are afraid to start a strength training program; they often feel as if it is too tough or dangerous for them to start strenuous activity. It is important for fitness professionals to promote the benefits and necessity of strength training for all groups, healthy or otherwise.