Obesity Screening

What is obesity screening?

Obesity screenings check for obesity and overweight in adults and children, starting as early as age 2. In general:

• Obesity means that you have too much body fat
• Overweight may mean that you have too much body fat, but the extra weight may also come from muscle, bone, or extra water in your body

Extra fat from obesity and overweight increases your risk of developing serious, long-lasting health problems, such as heart and blood vessel diseases, including heart attack and stroke.

Many things can cause someone to develop obesity or become overweight, such as:

• Certain health conditions, such as metabolic syndrome, hypothyroidism, and polycystic ovary syndrome (in females only)
• Certain medicines, such as some antidepressants, beta-blockers (used to treat high blood pressure), steroids (used to treat autoimmune disease), and some diabetes medicines
• Eating habits, such as diets that include high amounts of saturated fat and sugar
• Not getting enough physical activity, which can make it harder for your body to burn more calories than you're using (causing you to gain weight)
• Poor-quality sleep or not enough sleep, which can affect the hormones that control hunger and make you more likely to overeat
• High stress levels, which can affect your brain and trigger changes in your hormones that make you eat more and store more fat
• A family history of obesity, which can be caused by inherited genes that affect your weight and by the dietary and exercise habits of your family members

Obesity and overweight are also more common in certain communities with limited access to healthy foods. For example, African American and Hispanic communities have higher rates of obesity and overweight than white and Asian American communities.

Measuring body fat is difficult and expensive. So, obesity screening estimates how much body fat you have. The estimate is made with a calculation called a BMI (body mass index). In some cases, your health care provider may also measure the circumference of your waist.

How is a BMI calculated?

BMI for adults ages 20 and older is calculated from height and weight information. The result is a number called a BMI score. Higher BMI scores are linked to larger amounts of body fat and a higher risk for certain health problems. For most adults:

• A healthy weight is a BMI between 18.5 and 24.9
• Overweight is a BMI between 25 and 29.9
• Obesity is a BMI of 30 and above

There are also three classes of obesity. These are:

• Class 1 obesity, which is a BMI between 30 and 34.9
• Class 2 obesity, which is a BMI between 35 and 39.9
• Class 3 obesity, which is a BMI of 40 and above

BMI for children over age 2 and teens is also based on weight and height. But age and sex are part of figuring out if a child or teen has too much body fat. That's because the normal amount of body fat can vary depending on the child or teen's sex and stage of growth.

To adjust for these differences, your child's BMI is compared to standard growth charts for children of their age and sex. The result is called a BMI percentile. For example, if your child's BMI is in the 25th percentile, it means that 25% of children the same age and sex have a lower BMI, and 75% have a higher BMI.

Because height and weight changes with growth, your child's BMI will be tracked over time so that your provider can see if obesity or overweight are causing any health problems. For most children and teens:

• A healthy weight is a BMI between the 5^th and 85^th percentile
• Overweight is a BMI between the 85^th and 94^th percentile
• Obesity is a BMI in the 95^th percentile or higher

A BMI is a fairly accurate way to screen most people for too much body fat, but it's not perfect. For example, your BMI can't tell if your weight is from extra fat or muscle. This means a very muscular person could have a BMI in the overweight range even though they don't have too much body fat. BMI also can't see where in the body someone is carrying fat.

Also, some people who have a healthy BMI may still have high amounts of body fat. This may be more common in groups that tend to have lower BMI scores, such as people of Asian descent and older adults who have lost muscle. Talk with your provider if you have questions about how accurate a BMI is for your body type.

What is an obesity screening used for?

Obesity screening with a BMI is used to find out if an adult or a child has an unhealthy body weight for their height. This helps a provider understand a person's risk for diseases that are linked to extra body fat. Along with heart and blood vessel disease, these include:

• High blood cholesterol
• Type 2 diabetes
• Metabolic dysfunction-associated steatotic liver disease (MASLD)
• Arthritis
• Certain types of cancer

The more fat you have, the higher your risk of developing these health problems. Being overweight and having obesity can also raise your risk for other conditions, such as:

• Kidney disease
• Gallstones
• Depression
• Female infertility
• Memory problems

Children who have obesity may develop many of the same health problems as adults with obesity. They are also more likely to have obesity in adulthood and develop serious health problems later in life.

Obesity screening doesn't show the amount of fat a person has. It also can't diagnose any health conditions on its own. So, other tests may be needed. A BMI may also be used to find out if weight-loss efforts are working.

Why do I need obesity screening?

Most adults and children ages 2 and older should be screened with a BMI at least once a year. These screenings can help your provider see any changes in your BMI over time. If your score gets higher, it usually means you're gaining extra fat. Even if your higher BMI stays in the healthy range, weight gain from fat can still increase your risk for weight-related diseases. Obesity screening can help catch weight gain early so you can take steps to control your weight before it harms your health.

If you already have obesity or are overweight, screening helps your provider monitor your risk for health problems related to body fat. Information about your risk level helps you and your provider consider the pros and cons of different weight-loss treatments.

What happens during an obesity screening?

An obesity screening is usually part of a routine checkup that includes a physical exam. Your provider will measure your height and weight. That information is usually entered into an online BMI calculator. If you know your height and weight, you can find your BMI online using:

• This BMI calculator for adults
• This BMI percentile calculator for children and teens

Your provider may also use other tests to estimate how much body fat you have. These include:

• A waist measurement. Adults who have too much fat around their abdomen (belly) have an increased risk of developing conditions related to obesity. Even if you have a healthy BMI, your risk may be high if your waist size is:
  • More than 40 inches for men
  • More than 35 inches for women who aren't pregnant

Skinfold measurements. A skinfold test measures the thickness of a pinch of skin and fat at several places on your body. A special tool gently measures skinfolds on your belly, back, thigh, the back of your upper arm, and other places on your body. The results are used to estimate how much of your body is fat.

If your obesity screening shows that you may have too much body fat, your provider may ask questions to help find out why. This often includes discussing your medical and family history, eating and sleeping habits, and physical activity.

Will I need to do anything to prepare for an obesity screening?

You don't need to prepare for an obesity screening. If you're also having certain blood tests to learn more about your health, you may need to fast (not eat or drink) for a period of time. Your provider will let you know how to prepare.

Are there any risks to the screening?

There is no risk to having a BMI or a measurement of your waist or skinfolds.

What do the results mean?

If an obesity screening shows that you have obesity or are overweight, your provider will work with you to develop a treatment plan. The goal of the plan is to reduce your risk of health problems linked to extra body fat.

Your plan will depend on how much weight you need to lose and the cause of your weight gain. Most plans are likely to include lifestyle changes, such as:

• Eating a healthier, lower calorie diet
• Getting more exercise
• Getting enough good-quality sleep
• Managing your stress and mental health

Depending on your BMI and health, your provider may also suggest:

• Support from a dietary or nutritional counselor
• A behavioral weight-loss treatment program
• Prescription weight-loss medicines combined with lifestyle changes
• Weight loss surgery

If you have questions about obesity screening or treatments to lower your BMI, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.