How Obesity Is Diagnosed?

Diagnosing obesity involves much more than stepping on a scale. In fact, a thorough evaluation of a person’s weight status is a complex procedure that takes many factors into account and uses a variety of tools and diagnostic tests, including body mass index (BMI), waist circumference measurement, physical exams, and lab tests to monitor for co-morbidities.

Very good / Laura Porter

Self Checks/Home Testing

Over the past 40 years, obesity has become a major global health problem. “Obesity is a serious concern because it is associated with poorer mental health outcomes, decreased quality of life, and the leading cause of death in the US and worldwide,” says the Centers for Disease Control and Prevention (CDC).

The most successful obesity treatment strategy involves early diagnosis and intervention. Studies have shown that getting a formal diagnosis of obesity is more likely to lead to weight loss (compared to those who are never diagnosed).

Body Mass Index (BMI)

The most commonly used scale health care providers use to diagnose obesity is called the body mass index. BMI takes into account the body’s total fat content, expressed by dividing a person’s weight (in kilograms) by the square of a person’s height (in meters).

A normal BMI ranges from 18.5 to 24.9 (kg weight per square meter of length).

BMI can be evaluated as part of a self-test for obesity screening by accessing the CDCs online tool for measuring BMI for adultsor the online tool for measuring BMI for children and teenagers

Waist Circumference Measurement:

Fat stored in the abdominal area is called visceral fat, which can further increase the risk of diseases such as heart disease and diabetes. In people with a BMI between 25 and 34.9, a waist circumference of more than 35 centimeters in women and more than 40 centimeters in men is associated with an increased risk of disease.

It can be helpful to keep an eye on this reading, as changes in waist circumference are an independent risk predictor regardless of overall weight if you’re in the normal to overweight range on the BMI scale.

Waist size should be considered at least annually. A person can take a waist measurement as a self-test to screen for a high risk of obesity. However, other measurements (such as BMI) should also be taken into account as waist circumference thresholds are not reliable for patients with a BMI over 35. Also, waist circumference may not be a reliable indicator of belly fat for all ethnicities, genders, and age groups.

Also Read:  An overview of childhood obesity

Other diagnostic measures

Other diagnostic measures used to identify or evaluate obesity include:

    A physical exam that evaluates height, weight, and vital signs, as well as a general assessment from head to toe. A health history. A history of weight loss efforts, exercise, and eating habits. A family history assessment (to evaluate the possibility of hereditary factors)

Labs and Tests

It is important to understand the importance of seeking professional help when it comes to diagnosing obesity in children, adolescents or adults.

Diagnostic testing for obesity and overweight may involve some lab tests to evaluate the extent to which the condition has affected a person’s overall health and to check for signs of underlying disease. The lab tests your healthcare provider will order will depend on many factors, such as your risk factors for obesity-related diseases and current symptoms.

Laboratory tests may include:

    Cholesterol levels: low “good” cholesterol (HDL) and high “bad” cholesterol (LDL) levels, which are often associated with obesity. Fasting blood sugar and hemoglobin A1C (HbA1C) to check for signs of prediabetes or diabetes. A thyroid test to observe for signs of thyroid disease, often associated with obesity Liver function tests to screen for the potential of fatty liver, often associated with obesity

Other tests may be ordered by your healthcare provider to evaluate the overall impact of obesity on the body. One such test is an electrocardiogram (ECG or EKG), which is used to look for signs of heart disease.

Diagnosing childhood obesity

To diagnose childhood obesity, a health care provider will use a growth chart to evaluate how a child’s weight and height compare to other children of the same age and sex. For example, a child who falls in the 90th percentile will weigh more and have a higher BMI than 90% of other children of the same age and sex.

The CDC has developed growth charts to help diagnose overweight and obese children. A child in the 85th-94th percentile is considered overweight and a child in the 95th percentile or higher is considered obese.

Because growth patterns and body frames can vary drastically from child to child, pediatricians consider several factors when diagnosing a child’s weight status. Including:

    Growth charts Family history of obesity Eating habits Activity level Psychosocial history (including sleep patterns, mood disorders such as depression, social interactions, and factors such as being bullied) Other health problems

Laboratory tests that may be ordered when a child is suspected of being overweight include:

    A cholesterol testA blood sugar testBlood tests to check for hormonal imbalancesBlood tests to check for obesity-related conditions

Diagnosing Adolescent Obesity

To diagnose obesity in adolescents, the BMI scale is used in conjunction with comparing adolescents to other teens of the same age and gender. Adolescents in the 95th percentile or above (for age and gender) or those with a BMI of 30 or more are considered obese.

Teens in this category receive a full medical exam, including:

    A medical historyA physical examLab testsX-rays

According to Stanford Children’s Health, adolescents with a BMI between the 85th and 95th percentiles or with a BMI equal to 30 are automatically placed in a risk category in which they receive a second screening in five areas. Including:

    A family history A blood pressure screening A lab test for total cholesterol to check for LDL, HDL and triglycerides An annual BMI evaluation (looking for big jumps in BMI from year to year) An assessment of personal concerns about weight (including a psychological screening and a evaluation of self-perception and emotional response to overweight)

Diagnosis of morbid obesity

The BMI scale is the primary method of distinguishing between obesity and morbid obesity. According to the World Health Organization (WHO), obesity is defined as a BMI equal to or greater than 30.

A person is considered morbidly obese when their body weight is 100 pounds above the ideal level for his or her height, with a BMI of 40 or more. Morbid obesity is also diagnosed with a BMI of 35 or more for a person with an obesity-related disease such as diabetes or high blood pressure.

Differential diagnosis

There are many factors to consider as part of a thorough diagnosis of obesity, other than just a person’s weight status. Knowing what to expect and how to ensure an accurate weight evaluation can be the difference between a correct diagnosis — leading to early intervention — and a misdiagnosis of a person’s weight status.

Accuracy of the BMI rating scale

BMI is not always a completely accurate measurement when it comes to diagnosing obesity. Some individuals, namely athletes with a large percentage of muscle mass, may shake the accuracy of the scale. This is because athletes have very high body mass, but very little body fat.

Several studies have been conducted to evaluate the accuracy of BMI calculations compared to other techniques for measuring body fat. While some research findings have diverged, there is strong evidence that standard BMI scores underestimate the composition of body fat (fat).

According to the American Medical Association’s AMA Journal of Ethics, “A BMI equal to or greater than 30 has a 50% sensitivity in detecting excessive obesity, meaning that half of those with a high percentage of body fat will not become obese.” In addition, because BMI calculations use total weight in the denominator, some lean subjects with preserved muscle mass may be labeled as overweight.”

In addition, BMI measurements do not take into account the overall fat distribution, which means that people who are slightly overweight or of normal weight, for example, who have a lot of belly fat (visceral fat), cannot be considered at risk according to the BMI criteria.

Tests that could improve the accuracy of an obesity diagnosis

Body fat can be measured in several ways. In addition to BMI, these measurements can help improve the accuracy of an obesity diagnosis:

    Waist circumference: Helps identify adipose tissue called visceral fat that surrounds the body’s organs Ultrasound: Measures the thickness of the body’s adipose tissue Skinfold measurements: A pinch test using a device called a bioelectrical impedance instrument to determine the estimate amount of total body fat

The bioelectrical impedance instrument squeezes the skin in various parts of the body and pulls the skin away from the underlying muscle tissue to measure the width of the adipose tissue.

Typically, several skin folds are measured, including:

    Biceps Triceps Subscapular (below the shoulder blade)Suprailiac (above the hip bone)Pectoral (the center of the chest)Midaxilla (midline of the side of the trunk)Abdomen Quadriceps (the upper thigh)

A skinfold test and other diagnostic tools are often used in conjunction with the BMI scale to more accurately identify the signs and symptoms of obesity.

Frequently Asked Questions

    Is obesity genetic?

    There are genetic factors that increase the risk of certain people becoming obese. However, there are ways to combat the genetic link, and there are many other risk factors that lead to obesity.

    How do you prevent obesity?

    To prevent obesity, start as early as possible and make smart dietary decisions, such as reducing sugar and saturated fat, avoiding processed foods, and drinking plenty of water. Regular exercise is also important to maintain a healthy weight. Limiting stress and getting enough sleep also help reduce the risk of obesity.

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