Chapter 4 of health ed

Maintaining your weight

"in balance." You are eating roughly the same number of calories that your body is using. Your weight will remain stable.

Losing weight

"in caloric deficit." You are eating fewer calories than you are using. Your body is pulling from its fat storage cells for energy, so your weight is decreasing.

Gaining weight

"in caloric excess." You are eating more calories than your body is using. You will store these extra calories as fat and you'll gain weight.

If an athlete or other person with a lot of muscle has a BMI over 25, is that person still considered to be overweight?

According to the BMI weight status categories, anyone with a BMI between 25 and 29.9 would be classified as overweight and anyone with a BMI over 30 would be classified as obese. However, athletes may have a high BMI because of increased muscularity rather than increased body fatness. In general, a person who has a high BMI is likely to have body fatness and would be considered to be overweight or obese, but this may not apply to athletes. A trained healthcare provider should perform appropriate health assessments in order to evaluate an individual's health status and risks.

How is BMI used?

A high BMI can be an indicator of high body fatness. BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual. To determine if a high BMI is a health risk, a healthcare provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.

According to data from the National Health and Nutrition Examination Survey (NHANES):

About 1 in 3 adults were considered to be overweight. More than 2 in 3 adults were considered to be overweight or have obesity. More than 1 in 3 adults were considered to have obesity. About 1 in 13 adults were considered to have extreme obesity. About 1 in 6 children and adolescents ages 2 to 19 were considered to have obesity.

Health Effects of Overweight and Obesity

All causes of death (mortality) High blood pressure (Hypertension) High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (Dyslipidemia) Type 2 diabetes Coronary heart disease Stroke Gallbladder disease Osteoarthritis (a breakdown of cartilage and bone within a joint) Sleep apnea and breathing problems Some cancers (endometrial, breast, colon, kidney, gallbladder, and liver) Low quality of life Mental illness such as clinical depression, anxiety, and other mental disorders Body pain and difficulty with physical functioning

What is BMI? ( body mass index)

BMI is a person's weight in kilograms divided by the square of height in meters. BMI does not measure body fat directly, but research has shown that BMI is moderately correlated with more direct measures of body fat obtained from skinfold thickness measurements, bioelectrical impedance, densitometry (underwater weighing), dual energy x-ray absorptiometry (DXA) and other methods. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcomes as are these more direct measures of body fatness. In general, BMI is an inexpensive and easy-to-perform method of screening for weight categories, for example underweight, normal or healthy weight, overweight, and obesity.

Why is BMI used to measure overweight and obesity?

BMI can be used for population assessment of overweight and obesity. Because calculation requires only height and weight, it is inexpensive and easy to use for clinicians and for the general public. BMI can be used as a screening tool for body fatness but is not diagnostic. To see the formula based on either kilograms and meters or pounds and inches, visit How is BMI calculated? What are some of the other ways to assess excess body fatness besides BMI? Other methods to measure body fatness include skinfold thickness measurements (with calipers), underwater weighing, bioelectrical impedance, dual-energy x-ray absorptiometry (DXA), and isotope dilution 1,2,3. However, these methods are not always readily available, and they are either expensive or need to be conducted by highly trained personnel. Furthermore, many of these methods can be difficult to standardize across observers or machines, complicating comparisons across studies and time periods.

How is BMI interpreted for adults?

For adults 20 years old and older, BMI is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages.

Causes and Health Consequences of Overweight and Obesity

Factors that may contribute to weight gain among adults and youth include genes, eating habits, physical inactivity, TV, computer, phone, and other screen time, sleep habits, medical conditions or medications, and where and how people live, including their access to healthy foods and safe places to be active. Overweight and obesity are risk factors for many health problems such as type 2 diabetes, high blood pressure, joint problems, and gallstones, among other conditions.

If you are maintaining your current body weight, you are in caloric balance. If you need to gain weight or to lose weight, you'll need to tip the balance scale in one direction or another to achieve your goal.

If you need to tip the balance scale in the direction of losing weight, keep in mind that it takes approximately 3,500 calories below your calorie needs to lose a pound of body fat. To lose about 1 to 2 pounds per week, you'll need to reduce your caloric intake by 500—1000 calories per day. To learn how many calories you are currently eating, begin writing down the foods you eat and the beverages you drink each day. By writing down what you eat and drink, you become more aware of everything you are putting in your mouth. Also, begin writing down the physical activity you do each day and the length of time you do it. Here are simple paper and pencil tools to assist you:

Balancing Calories

More than one third of U.S. adults are obese. Weight gain occurs when you consume more calories than your body uses. Reaching and maintaining a healthy weight will help you prevent and control many diseases and conditions. The key is "Finding a Balance" in your lifestyle that includes healthy eating and regular physical activity.

How good is BMI as an indicator of body fatness?

The correlation between BMI and body fatness is fairly strong, but even if 2 people have the same BMI, their level of body fatness may differ. In general: At the same BMI, women tend to have more body fat than men. At the same BMI, Blacks have less body fat than do Whites, and Asians have more body fat than do Whites At the same BMI, older people, on average, tend to have more body fat than younger adults. At the same BMI, athletes have less body fat than non-athletes.

What are the BMI trends for adults in the United States?

The prevalence of adult BMI greater than or equal to 30 kg/m2 (obese status) has greatly increased since the 1970s. Recently, however, this trend has leveled off, except for older women. Obesity has continued to increase in adult women who are age 60 years and older.

Your weight is the result of many factors

These factors include environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and more. You can't change some factors, such as family history. However, you can change other factors, such as your lifestyle habits. For example, follow a healthy eating plan and keep your calorie needs in mind. Be physically active and try to limit the amount of time that you're inactive. As shown in the video below, it is important to remember that obesity happens one pound at a time, and even relatively small weight gains can negatively affect one's health and well-being.

BMI

Weight Status Below 18.5 Underweight 18.5 - 24.9 Normal or Healthy Weight 25.0 - 29.9 Overweight 30.0 and Above Obese

The Caloric Balance Equation

When it comes to maintaining a healthy weight for a lifetime, the bottom line is - calories count! Weight management is all about balance—balancing the number of calories you consume with the number of calories your body uses or "burns off." A calorie is defined as a unit of energy supplied by food. A calorie is a calorie regardless of its source. Whether you're eating carbohydrates, fats, sugars, or proteins, all of them contain calories. Caloric balance is like a scale. To remain in balance and maintain your body weight, the calories consumed (from foods) must be balanced by the calories used (in normal body functions, daily activities, and exercise).

Worldwide Obesity Statistics from the World Health Organization

Worldwide obesity has nearly tripled since 1975. In 2016, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 650 million were obese. 39% of adults aged 18 years and over were overweight in 2016, and 13% were obese. Most of the world's population live in countries where overweight and obesity kills more people than underweight. 41 million children under the age of 5 were overweight or obese in 2016. Obesity is preventable.

If you are...

Your caloric balance status is...