The prevalence of obesity in American citizens has been dramatically on the rise in the last decade.

According to the Centers for Disease Control, obesity has increased 74 percent since 1991. Forty-four million Americans are considered to be obese.

An individual is considered to be obese when their body mass index is above 30. Body mass index (BMI) is the measure of body fat based on height and weight.

Poor nutrition and sedentary lifestyles are linked to obesity and health problems. In relation, health care costs have been rising with obesity rates in the United States, said Gregory Welk, assistant professor of health and human performance.

Welk has researched the correlation between physical activity and body composition.

“Obesity stems from a genetic predisposition and environmental or behavioral influences,” Welk said.

Welk and his graduate students recently reviewed literature for the American Dietetics Association to determine a solid link between physical inactivity and obesity.

Convenience-based products help people remain sedentary, and the introduction of the Internet even allows shopping from the convenience of a chair, said Jodee Schaben, graduate student in exercise and sport science.

“Technology has given Americans the right to be lazy,” Schaben said. “Many years ago, people had to be physically active to survive and perform everyday tasks. Obesity wasn’t a problem then.”

Stress and hectic schedules play a large role in the lifestyle an individual adapts, said Michelle Ihmels, graduate student in exercise science.

“People do not take the time for exercise or healthy eating, the vital importance of each is not understood,” Ihmels said.

A lifestyle that includes daily physical activity is essential to good health and disease prevention, especially diseases that are associated with obesity, she said.

“Not only do we exercise less, we eat more,” said Tim Lane, director of health promotion at the Iowa Department of Public Health. “People are eating outside the home more than they used to, and are consuming larger portions.”

According to the National Institutes of Health, restaurant portion sizes have gotten larger in the last 10 years. Some portions of these high-calorie foods are “super-sized,” while even regular items have grown in size to provide enough food for at least two people.

For example, the McDonald’s nutrition information Web site lists a quarter-pounder with cheese extra value meal, including large fries and a drink as containing 1,380 calories and 56 grams of fat.

According to the U.S. Department of Agriculture, the guideline for an average American is a 2,000 calorie diet with less than 65 grams of fat per day. A super size meal is almost an entire day’s worth of calories and fat.

Fast food is a tempting option for many Americans because of its availability and low cost, Schaben said.

“Cooking seems to take so much time when you can pick up a bucket of chicken in five minutes to feed the whole family,” she said.

Statistics from the Center for Disease Control claim that only three percent of Americans consume at least four of the five federal Food Guide Pyramid recommendations for intake of grains, fruits, vegetables, dairy and meats.

The economics of eating healthy are one of the reasons why it is hard for Americans to eat well, Welk said.

“Who can argue with an entire meal for 3 dollars?” he said.

Fast food provides a fast, hassle-free, cheap source of food. Lower income families, college students and busy people find this combination very appealing, Welk said.

“An entire, unhealthy fast food meal can be bought for the same price as a carton of vitamin-rich strawberries at the grocery store,” Schaben said.

“The increased calorie intake and decreased activity doesn’t just mean that Americans are getting fatter. It [also] costs well over a billion dollars a year and increases mortality rates,” Lane said.

In fact, the U.S. surgeon general’s report last December said obesity kills an estimated 300,000 Americans each year and costs $117 billion in health-related costs.

“Obesity itself is not the risk,” Lane said. “It’s diseases such as diabetes, hypertension and cardiovascular disease that are caused by physical inactivity and poor nutrition, which in turn leads to obesity that cost.”

There are people who are thin or average sized that eat poorly and do not exercise — these people are just as unhealthy as obese people, Ihmels said. They are equally at risk for the diseases associated with obesity and an unhealthy lifestyle.

According to the Center for Disease Control, 70 percent of adults are not achieving the recommended 30 minutes of moderately intense physical activity at least five days per week.

It is hard for people to include exercise time in their daily schedule — it needs to be part of their lifestyle, Welk said.

“Public health officials are working on making our communities more physical-activity friendly, but much more needs to be done,” said Diane Birt, department chair of the department of Food Science and Human Nutrition.