ANN ARBOR, MI - — We're less active. We eat super-sized portions of greasy, processed food. And as a society we're getting older.

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Combine these factors and you get a population in which nearly a quarter of the country is obese. It's a $100 billion burden that appears to be getting worse.

“The main reasons for the increase in the prevalence of obesity I believe have to do with modern lifestyle: We as a society produce food in large quantities and people have gotten used to eating large portions of food,” says endocrinologist David Schteingart, M.D., associate director of the General Clinical Research Center at the University of Michigan Health System.

At the same time, people tend not to be as physically active. Entertainment has gone from playing sports in the park to playing video game sports. And urban sprawl has made driving rather than walking or bicycling the standard method for getting around.

“All of that has resulted in a change in our energy balance, so that we tend to store calories instead of using them,” says Schteingart, a professor of internal medicine at U-M Medical School.

Extra weight carries with it a host of medical problems. People who are overweight are three to five times more likely to have high blood pressure, and they're more likely to develop Type 2 diabetes. Heart attacks and stroke are also linked to obesity, as are certain cancers, including uterine cancer and gastrointestinal cancers.

Obesity means a person weighs more than 20 percent above his or her ideal weight. It's not simply a result of eating too much. The amount of energy each person's body needs when at rest varies, and people who are obese may require less. Further, physical activity is often more difficult because of the excess weight.

Some evidence suggests a possible genetic link to obesity. Children whose parents are obese are 10 times more likely to be obese as well.

“All you have to do is look at families and realize that if somebody in the family is overweight, it's likely the other people in the family are overweight,” Schteingart says. “But if obesity occurs with a familial pattern, is it because of genetics or is it because people share the same habits and the same eating patterns from the word go? In other words, do they inherit the behavior pattern more than the biological patterns that will make them become overweight?”

Research seems to point to some genetic influence and scientists are now working to determine what genes are involved in weight. Genes have been identified that control how fat is distributed through a person's body.

“There is evidence also that the way people use their energy is probably genetically determined. There are people who are energy efficient and people who are energy inefficient, and that seems to cluster in families,” Schteingart says.

Weight gain is also more common as people age. This middle-age weight creep is a combination of biological and environmental factors. First, energy expenditure declines about 7 percent every 10 years. So at age 60, people do not need to eat as much as they did at age 20. In addition, muscle mass – which consumes the most energy – decreases as we age, resulting in lower energy needs.

“There are also environmental factors involved as we age. We tend to be less physically active, and we adopt lifestyles more conducive to gaining weight,” Schteingart says.

Losing weight

Weight gain occurs over a long period, and similarly weight loss won't happen overnight. The key is to institute changes in your diet and lifestyle that are sustainable long-term. Here are some tips:

• Follow a plan for healthy eating. Avoid fasting, fad diets and diet drugs.
• Take a class in preparing low-calorie meals or find new recipes in low-calorie cookbooks.
• Keep a daily record of everything you eat and drink. Don't forget to write every nibble down!
• Drink at least eight 8-ounce glasses of water a day, and avoid alcohol.
• Join a weight loss support group.
• Substitute relaxation techniques such as deep breathing during stressful times when you're tempted to eat.
• Begin introducing physical activity such as walking or swimming.

Being active

Exercise can help you burn off calories and increase your metabolic rate. Again, your goal is develop a routine that can become part of your everyday life. Here are some tips to keep you motivated:

• Take the stairs instead of the elevator.
• Do errands on foot. If you drive to the store, park farther away from the doors.
• Find a physical activity that you enjoy. This can be a team sport, a brisk walk or an aerobics tape at home.
• Recruit a friend to exercise with you.
• Join a gym or exercise class.
• Start slow and build your stamina gradually. Don't set your expectations too high and don't overdo it right from the start.

Are you overweight?

The most common screening for obesity or being overweight is the body mass index, or BMI. It's a measure of weight related to height, which makes it a better indicator of obesity than weight alone. To calculate your BMI, divide your weight in kilograms by your height in meters squared.

Using pounds and inches, the formula is:

• Multiply your weight in pounds by 704.5.
• Divide the result by your height in inches.
• Divide that result by your height in inches again.

A BMI of 25-29.9 indicates being overweight and a BMI of 30 or higher indicates obesity.

BMI is not perfect, though. Because it does not directly measure the percent of body fat, people who are very muscular will likely have a high BMI that labels them overweight when they're really healthy and fit.

Resources

About obesity:
www.med.umich.edu/1libr/aha/aha_obesity_crs.htm

The role of exercise in treating obesity: www.med.umich.edu/1libr/aha/aha_exercise_crs.htm

Losing weight:
www.med.umich.edu/1libr/aha/aha_losing_crs.htm

Weight-loss diets:
www.med.umich.edu/1libr/aha/aha_odiet_crs.htm

BMI calculator:
www.nhlbisupport.com/bmi/

Aim for a Healthy Weight: www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/patmats.htm

Written by Nicole Fawcett

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