Genetics and the environment may increase the risk of personal weight gain. However, the choices a person makes in eating and physical activity also contributes to overweight and obesity. Behavior can increase a person’s risk for gaining weight.
Looking back at the energy balance scale, weight gain is a result of extra calorie consumption, decreased calories used (reduced physical activity) or both. Personal choices concerning calorie consumption and physical activity can lead to energy imbalance.
Calorie Consumption
In America, a changing environment has broadened food options and eating habits. Grocery stores stock their shelves with a greater selection of products. Pre-packaged foods, fast food restaurants, and soft drinks are also more accessible. While such foods are fast and convenient they also tend to be high in fat, sugar, and calories. Choosing many foods from these areas may contribute to an excessive calorie intake. Some foods are marketed as healthy, low fat, or fat-free, but may contain more calories than the fat containing food they are designed to replace. It is important to read food labels for nutritional information and to eat in moderation.
Portion size has also increased. People may be eating more during a meal or snack because of larger portion sizes. This results in increased calorie consumption. If the body does not burn off the extra calories consumed from larger portions, fast food, or soft drinks, weight gain can occur.
Calories Used
Our bodies need calories for daily functions such as breathing, digestion, and daily activities. Weight gain occurs when calories consumed exceed this need. Physical activity plays a key role in energy balance because it uses up calories consumed.
Physical activity is any bodily movement produced by skeletal muscles that results in an expenditure of energy with a range of activities such as
- Occupational work
Carpentry, construction work, waiting tables, farming
- Household chores
Washing floors or windows, gardening or yard work
- Leisure time activities
Walking, skating, biking, swimming, playing Frisbee, dancing Structured sports or exercise Softball, tennis, football, aerobics
Regular physical activity is good for overall health. Physical activity decreases the risk for colon cancer, diabetes, and high blood pressure. It also helps to control weight, contributes to healthy bones, muscles, and joints; reduces falls among the elderly; and helps to relieve the pain of arthritis. Physical activity does not have to be strenuous to be beneficial. Moderate physical activity, such as 30 minutes of brisk walking five or more times a week, also has health benefits.
Despite all the benefits of being physically active, most Americans are sedentary. Technology has created many time and labor saving products. Some examples include cars, elevators, computers, dishwashers, and televisions. Cars are used to run short distance errands instead of people walking or riding a bicycle. As a result, these recent lifestyle changes have reduced the overall amount of energy expended in our daily lives. According to the Behavioral Risk Factor Surveillance System, in 2000 more than 26% of adults reported no leisure time physical activity.
The belief that physical activity is limited to exercise or sports, may keep people from being active. Another myth is that physical activity must be vigorous to achieve health benefits. Physical activity is any bodily movement that results in an expenditure of energy. Moderate-intensity activities such as household chores, gardening, and walking can also provide health benefits. Confidence in one’s ability to be active will help people make choices to adopt a physically active lifestyle.
Environment
People may make decisions based on their environment or community. For example, a person may choose not to walk to the store or to work because of a lack of sidewalks. Communities, homes, and workplaces can all influence people's health decisions. Because of this influence, it is important to create environments in these locations that make it easier to engage in physical activity and to eat a healthy diet. The Surgeon General’s Call to Action to Prevent and Decrease Overweight and Obesity 2001 identified action steps for several locations that may help prevent and decrease obesity and overweight. The following table provides some examples of these steps.
| Location |
Steps to Help Prevent and Decrease Overweight and Obesity |
| Home |
|
| Schools |
- Ensure that the school breakfast and lunch programs meet nutrition standards
- Provide food options that are low in fat, calories, and added sugars
- Provide all children, from prekindergarten through grade 12, with quality daily physical education
|
| Work |
- Create more opportunities for physical activity at work sites
|
| Community |
- Promote healthier choices including at least 5 servings of fruits and vegetables a day, and reasonable portion sizes
Encourage the food industry to provide reasonable food and beverage portion sizes
Encourage food outlets to increase the availability of low-calorie, nutritious food items
Create opportunities for physical activity in communities
|
How do genes affect obesity?
Science shows that genetics plays a role in obesity. Genes can directly cause obesity in disorders such as Bardet-Biedl syndrome and Prader-Willi syndrome.
However genes do not always predict future health. Genes and behavior may both be needed for a person to be overweight. In some cases multiple genes may increase one’s susceptibility for obesity and require outside factors; such as abundant food supply or little physical activity.
Other Factors
Some illnesses may lead to obesity or weight gain. These may include Cushing's disease, and polycystic ovary syndrome. Drugs such as steroids and some antidepressants may also cause weight gain.
A doctor is the best source to tell you whether illnesses, medications, or psychological factors are contributing to weight gain or making weight loss hard.
What is the prevalence of overweight and obesity among U.S. adults?
Results from the 2003-2004 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 66 percent of U.S. adults are either overweight or obese.
What is the prevalence of overweight among U.S. children?
Results from the 2003-2004 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 17 percent of children and adolescents ages 2-19 years are overweight.
What is the difference between being overweight and being obese?
Overweight and obesity are both labels for ranges of weight that are greater than what is generally considered healthy for a given height. The terms also identify ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.
For adults, overweight and obesity ranges are determined by using weight and height to calculate a number called the “body mass index” (BMI).
See the following table for an example.
| Height |
Weight Range |
BMI |
Considered |
| 5’ 9” |
124 lbs or less |
Below 18.5 |
Underweight |
| 125 lbs to 168 lbs |
18.5 to 24.9 |
Healthy weight |
| 169 lbs to 202 lbs |
25.0 to 29.9 |
Overweight |
| 203 lbs or more |
30 or higher |
Obese |
It is important to remember that although BMI correlates with the amount of body fat, BMI does not directly measure body fat. As a result, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat.
For children and teens, BMI ranges above a normal weight have different labels (at risk of overweight and overweight). Additionally, BMI ranges for children and teens are defined so that they take into account normal differences in body fat between boys and girls and differences in body fat at various ages.
What are some of the factors that contribute to overweight and obesity?
Researchers have found that several factors can contribute to the likelihood of someone’s becoming overweight or obese.
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Behaviors. What people eat and their level of physical activity help determine whether they will gain weight. A number of factors can influence diet and physical activity, including personal characteristics of the individual, the individual’s environment, cultural attitudes, and financial situation.
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Genetics. Heredity plays a large role in determining how susceptible people are to becoming overweight or obese. Genes can influence how the body burns calories for energy and how the body stores fat.
How does being overweight or obese affect a person’s health?
When people are or overweight or obese, they are more likely to develop health problems such as the following:
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Hypertension
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Dyslipidemia (for example, high total cholesterol or high levels of triglycerides)
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Type 2 diabetes
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Coronary heart disease
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Stroke
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Gallbladder disease
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Osteoarthritis
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Sleep apnea and respiratory problems
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Some cancers (endometrial, breast, and colon)
The more overweight a person is, the more likely that person is to have health problems. Among people who are overweight and obese, weight loss can help reduce the chances of developing these health problems. Studies show that if a person is overweight or obese, reducing body weight by 5 percent to 10 percent can improve one’s health.
What are the costs associated with overweight and obesity?
According to The Surgeon General’s Call to Action to Prevent and Decrease Overweight and Obesity, the cost of obesity in the United States in 2000 was more than $117 billion ($61 billion direct and $56 billion indirect).
What are some suggestions for losing weight?
Most experts recommend that someone attempting to lose a large amount of weight consult with a personal physician or health care professional before beginning a weight-loss program. The Surgeon General’s Healthy Weight Advice for Consumers makes the following general recommendations:
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Aim for a healthy weight. People who need to lose weight should do so gradually, at a rate of one-half to two pounds per week.
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Be active. The safest and most effective way to lose weight is to reduce calories and increase physical activity.
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Eat well. Select sensible portion sizes and follow the Dietary Guidelines for Americans.
How can physical activity help prevent overweight and obesity?
Physical activity, along with a healthy diet, plays an important role in the prevention of overweight and obesity (USDHHS, 2001). In order to maintain a stable weight, a person needs to expend the same amount of calories as he or she consumes.
Although the body burns calories for everyday functions such as breathing, digestion, and routine daily activities, many people consume more calories than they need for these functions each day. A good way to burn off extra calories and prevent weight gain is to engage in regular physical activity beyond routine activities.
If you eat 100 more food calories a day than you burn, you’ll gain about 1 pound in a month. That’s about 10 pounds in a year. The bottom line is that to lose weight, it’s important to reduce calories and increase physical activity.
References
CDC
