ASSESSING FOR OVERWEIGHT AND OBESITY
Nurse practitioners, office and clinic nurses, school nurses, hospital nurses, physical therapists, and occupational therapists, among others, all play a role in the assessment and treatment of children, adolescents, and adults for overweight or obesity. Assessment guidelines include:
- Body mass index or other screening or diagnostic tool measurement
- Classification of overweight and obesity
- Past medical history
- Family history
- Social history
- Review of systems
- Physical examination
- Diagnostic testing for comorbidities
Body Mass Index (BMI)
The primary way a person is categorized as overweight or obese is by calculating body mass index, which expresses the relationship (or ratio) of weight to height. BMI is calculated as:
(Weight in pounds ÷ height in inches2) x 703
or
Weight in kg ÷ height in meters2
BMI continues to be used as a screening tool because it is inexpensive and easier than other methods and does not require technical equipment and training. However, BMI can be misleading because it does not directly calculate body fat and is not, therefore, diagnostic (CDC, 2021f).
Certain factors that affect BMI inaccuracy include:
- Biological and genetic differences among racial and ethnic groups are not taken into account.
- Athletic individuals tend to have a higher percentage of lean muscle mass and lower percentage of fat mass, which might place them incorrectly in the overweight category.
- Two people can weigh the same and have the same BMI, but risk for disease might not be the same depending on how the weight is distributed. BMI does not include waist circumference.
- BMI in the high-normal to overweight range in older adults may be protective against developing certain diseases and dying early.
(Cleveland Clinic, 2022)
BMI AND WEIGHT STATUS FOR ADULTS
BMI for adults 20 years and older is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages. The standard weight status categories are shown in the table below.
BMI | Weight Status |
---|---|
(CDC, 2021f; WHO, 2022b) | |
<18.5 | Underweight |
18.5–24.9 | Normal or healthy weight |
25.0–29.9 | Overweight (preobesity) |
≥30.0 | Obese |
≥40 | Severely (morbidly) obese |
BMI AND WEIGHT STATUS FOR CHILDREN
BMI is interpreted differently for children and teens even though it is calculated in the same manner as adult BMI. The BMI in children and teens needs to be age- and sex-specific since the amount of body fat changes with age and differs between boys and girls. All children older than 2 years should have their BMI calculated at least annually from measured height and weight.
After BMI is calculated for children and teens, it is expressed as a percentile. The percentile can be obtained from either a graph or a percentile calculator, which expresses a child’s BMI relative to other children of the same age and sex. BMI-for-age percentile growth charts are the most commonly used indicator to measure the size and growth patterns of children and teens in the United States.

Example of BMI growth chart. (Source: CDC, 2021f.)
BMI Percentile | Weight Status |
---|---|
*For children under 2 years of age, consult WHO Child Growth Standards. (CDC, 2021f) |
|
<5th percentile | Underweight |
5th to <85th percentile | Normal or healthy weight |
85th to <95th percentile | Overweight |
≥95th percentile | Obese |
OBESITY CLASSIFICATIONS
There are several classifications for degrees of obesity, with the most widely accepted being those from the World Health Organization (WHO) based on BMI (see table below).
BMI | Classification |
---|---|
(WHO, 2022b) | |
25–29.9 | Grade 1 overweight |
30–39.9 | Grade 2 overweight (commonly called obesity) |
≥40 | Grade 3 overweight (commonly called severe or morbid obesity) |
Other Screening and Diagnostic Tools
BMI has long been used as a way to define obesity in the United States, but experts are becoming increasingly critical of the approach, saying it does not paint a full picture of our health. Other tools are available, and the choice of the method for measuring weight or body fat composition depends on whether it is being obtained for clinical purposes or research and what degree of precision is required.
Other options that can be used to determine overweight or obesity include the following:
- Skinfold thickness uses calipers to determine how much body fat sits on top of muscle. It is a useful way of determining where the biggest fat deposits are, but it requires significant training to perform it properly and retraining to ensure healthcare workers continue to perform it correctly. If done correctly, skinfold thickness can be up to 98% accurate in determining body fat.
- Dual energy X-ray absorptiometry (DXA body scan) is more accurate than BMI but also much more expensive. It is generally the preferred method in a clinical setting when a more rigorous determination of body composition is needed. It uses a very low dose of radiation and is fairly simple for an operator to perform. Two beams are used to scan the body. One beam is absorbed more by fat than the other, so the computer can differentiate fat from other tissues, providing a percentage of body fat. It is widely considered the gold standard for measuring body tissue, bone, muscle, and fat.
- Waist circumference measurement has been found to be a useful (although not a completely accurate) predictor of obesity-related health risks. The National Heart, Lung, and Blood Institute recommends that waist circumference be <40 inches for men and <35 inches for women.
- Waist-to-hip ratio (waist circumference divided by hip circumference) is a measure of fat distribution. Those with abdominal adiposity are at increased risk of comorbidities. Men with a waist-hip ratio of 0.95 or more and women with a ratio of 0.85 or more are considered to be at increased cardiovascular risk.
- Bioelectrical impedance analysis is simple and widely used and relies on an electrical current to measure the fat and fat-free mass of the body. Accuracy in placement of electrodes is essential, as variations can result in large errors. Impedance is measured by applying electrodes to one arm and one leg or by having the individual stand on the foot plates of a special scale.
- CT or MRI imaging techniques can reliably determine patterns of body fat distribution. It is possible to obtain an accuracy of <1% margin of error using a series of scans.
- Nuclear magnetic resonance spectroscopy is similar in technology to MRI but is capable of discerning fat and glycogen within tissues as well as fat and lean mass overall.
- Hydrodensitometry (underwater weighing) is based on the fact that lean body tissue is denser than fat. This technique involves weighing a person on dry land and again while completely submerged under water. Underwater weighing was long considered to be the gold standard for determining body composition but has largely been replaced by newer methods. Equipment for hydrodensitometry is usually only available in research facilities.
- Whole-body plethysmography uses air displacement rather than water displacement. The person is placed sitting inside a special enclosed chamber after being weighed on a scale to determine mass measurement, and sensors determine the amount of air displaced by the person’s body. Body fat and lean muscle mass can then be calculated. This method works well in adults, school-aged children, and infants (using a device specifically designed for this age group) (Perreault, 2021a; Phillips & Shulman, 2021).
- Relative fat mass index (RFM) is a newer, better measure of body fatness than many indices currently in use, including BMI. RFM closely matches results obtained by DXA body scan. RFM is obtained simply by measuring height and waist circumference and plugging the figures into the following formula:
- Men: 64 – (20 x height/waist circumference) = RFM
- Women: 76 – (20 x height/waist circumference) = RFM
Classification | Females (% fat) | Males (% fat) |
---|---|---|
(MDApp, 2020) | ||
Essential fat | 10–13 | 2–5 |
Athletes | 14–20 | 6–13 |
Fitness | 21–24 | 14–17 |
Average | 25–31 | 18–24 |
Obese | ≥32 | ≥25 |
Past History
Determining a patient’s past history is focused on investigating the cause of obesity or overweight and should include:
- Age of onset of weight gain. The risk for any given degree of obesity seems to be greater in patients whose obesity begins before the age of 40 years, allowing a longer time period over which comorbid conditions can develop. Children with a low birth weight and those whose weight rises more rapidly in their first 10 years are at high risk for diabetes as adults. Children with obesity at age 7 and continue with obesity throughout puberty will almost certainly have it as adults. Even very modest weight gain after age 18 is also important, increasing the risk of cardiovascular disease and type 2 diabetes at all levels of initial BMI.
- Family history. The risk of comorbidities of obesity is greatly influenced by family history. Obesity in one or both parents is a predictor for the persistence of a child’s obesity into adulthood. Family history should include information about obesity in first-degree relatives (parents and siblings) and common comorbidities of obesity in first- and second-degree relatives (grandparents, uncles, aunts, half-siblings, nephews, and nieces).
- Developmental history. For children it is important to include history of growth delay and pattern of weight gain, as well as history of asthma or childhood cancers, both of which may contribute to the development of childhood obesity.
- History of weight-loss attempts can provide relevant insights into current weight-loss management strategies as well as evidence of eating disorders such as bulimia nervosa and binge eating.
- Dietary history includes an assessment of eating patterns (timing, content, and location of meals and snacks) and identification of foods that should be reduced, eliminated, or replaced.
- Eating disorders are present in almost 30% of patients who are obese. Identify bingeing, purging, lack of satiety, food-seeking behavior, night-eating syndrome, and other abnormal feeding habits.
- History of physical activity includes an assessment of frequency, duration, and intensity of physical activities such as formal exercising, transportation, occupation, household tasks, recreation, and time spent in sedentary activities. In addition, for children and adolescents, this history includes identification of barriers to walking or riding a bike to school, evaluations of time spent in play, school recess, physical education, and after-school and weekend activities, including frequency and intensity.
- Current and past medications. Medication-related weight gain is not uncommon, especially with certain types of drugs, including some diabetic medications, antipsychotics, antidepressants, and antiepileptics.
- Current health habits, including tobacco use and drug and alcohol use.
- History of smoking cessation. Cigarettes reduce appetite, and nicotine speeds up metabolism, increasing the number of calories used. On average, people gain 5 to 10 pounds in the months after they give up smoking.
(Perreault, 2021b; Vorvick, 2020; Klish, 2020; Hamdy, 2022)
Review of Body Systems
An inventory of body systems is completed in order to identify signs or symptoms a person may be experiencing or has experienced related to overweight and obesity, including:
- Obesity secondary to genetic syndromes, hormonal disease, iatrogenic medications
- Polycystic ovary syndrome (oligomenorrhea or amenorrhea)
- Low testosterone level, low sex drive, or erectile dysfunction in men
- Obstructive sleep apnea, hypoventilation syndrome
- Osteoarthritis in adults
- Foot, hip, or knee pain (orthopedic issues, slipped capital femoral epiphysis in children)
- Urinary stress incontinence
- Abdominal pain (gastroesophageal reflux disease, gallbladder disease, pancreatitis)
- Disability/immobility
- Blurred vision, history of glaucoma, diabetic retinopathy
- Psychological disorder and/or stigmatization, anxiety, depression, ADHD, PTSD, social isolation
- Medications being taken for depression or anxiety
- Polyuria, polydipsia, polyphagia (type 2 diabetes mellitus)
- Headaches (idiopathic intracranial hypertension, aka pseudotumor cerebri)
- Obesity secondary to genetic syndrome
(AACE, n.d.)
Physical Examination
Physical examination includes obtaining vital signs, height, weight, and BMI, and a complete head-to-toe examination in order to rule out any medical conditions that can be the cause of obesity and to assess for comorbid conditions.
General
- Sex, race, body build
- Obvious dysmorphic or distinguishing features that may suggest a genetic syndrome
- State of development in relation to chronological age (especially important in childhood and adolescence regarding evidence of secondary sex characteristics)
- Functional mobility, posture, gait
- Hygiene
Vital Signs
- Blood pressure. Elevated blood pressure may be a sign of Cushing’s syndrome. Normal blood pressure in adults ranges from 110/75 to 130/85. Pediatric blood pressure levels are interpreted based on sex, age, and height. Normal blood pressure values for children and adolescents are shown in the table below:
NORMAL BLOOD PRESSURE IN CHILDREN
(in mmHg)Age (years) Boys Girls (Mattoo, 2021) 1 98/52 98/54 3 101/58 102/60 5 103/63 104/64 7 106/68 106/68 9 107/70 108/71 11 110/74 111/74 ≥13 120/80 120/80
Head, Eyes, Ears, Nose, and Throat
- Microcephaly, a feature of Cohen syndrome (aka Pepper syndrome)
- Poor linear growth in children, which may be due to hypothyroidism, Cushing’s syndrome (high levels of cortisol), or Prader-Willi syndrome (a rare disorder present at birth)
- Papilledema, an optic disc swelling secondary to elevated intracranial pressure seen in patients with pseudotumor cerebri
- Nystagmus or visual complaints, which may be related to hypothalamic-pituitary lesion
- Clumps of pigment in the peripheral retina, which may indicate retinitis pigmentosa (Bardet-Biedl syndrome)
- Tonsillar enlargement secondary to sleep apnea
- Erosion of tooth enamel resulting from self-induced vomiting in those with an eating disorder
Skin and Hair
- Acanthosis nigricans, seen in those who have diabetes or prediabetes (children with acanthosis nigricans being at high risk of developing type 2 diabetes later in adulthood)
- Hirsutism and excessive acne, which may be related to polycystic ovary syndrome
- Skin tags, seen commonly with insulin resistance
- Purple striae on the abdomen, lower flank, breasts, hips, buttocks, shoulders, upper thighs, upper arms, and axillae, which is caused by rapid weight gain due to Cushing’s syndrome
Cardiac and Respiratory
- To exclude cardiomegaly and respiratory insufficiency
Abdomen
- Abdominal tenderness, which may be related to gallbladder disease, GERD, or nonalcoholic fatty liver disease
- Hepatomegaly and hepatic tenderness due to nonalcoholic fatty liver disease
Genitourinary
- Undescended testicles, small penis, or scrotal hypoplasia, which can occur in children with Prader-Willi syndrome
- Small testes, which may suggest Bardet-Biedl syndrome
- Delayed or absent puberty
- Precocious puberty
Extremities
- Limited hip range of motion, which could suggest a slipped capital femoral epiphysis
- Lower-leg bowing caused by Blount disease, in which the medial side of the tibia, immediately distal to the knee joint, fails to develop normally
- Pes planus (flat feet) and pronation of the feet, common in obese children
- Dorsal finger callouses, which may indicate self-induced vomiting
- Malformed or misshapen body parts (extra digit next to the fifth digit may present in Bardet-Biedl syndrome, small hands and feet in Prader-Willi syndrome)
- Evidence of osteoarthritis
(Burridge et al., 2022)
Laboratory Studies
ADULTS
Standard laboratory studies in the evaluation of an adult patient with obesity include:
- Fasting lipid panel. At minimum, fasting cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-C) levels should be done. Increased low-density lipoprotein cholesterol (LDL-C) and normal or marginally increased total cholesterol are not uncommon among obese individuals.
- Liver function studies results are normal in most obese patients. However, elevated transaminase levels may indicate nonalcoholic steatohepatitis (NASH) or fatty infiltration of the liver.
- Thyroid function tests. Although hypothyroidism itself rarely causes more than mild obesity, these tests can rule out primary hypothyroidism. Screening with a serum thyrotropin level is recommended as adequate. TSH levels are commonly elevated in persons with obesity.
- Glucose and insulin studies. All patients with obesity should be screened for diabetes and prediabetes, including a fasting glucose and hemoglobin A1C (HbA1C).
Other laboratory tests should be done as indicated by clinical findings and suspicions. When Cushing’s syndrome or other hypercortisolemic states are suspected, a 24-hour urinary free-cortisol test should be included (Hamdy, 2022).
CHILDREN AND ADOLESCENTS
Laboratory evaluation for children with obesity is focused on identification of any genetic or hormonal disorder that may be a cause of obesity in a child. The following is the suggested routine screening:
- Fasting lipid panel, done once between the ages of 9–11 and again between 17–21 for detection of dyslipidemia
- Glucose and insulin studies, including serum hemoglobin A1C level as well as fasting and two-hour glucola glucose and insulin levels for evaluation of glucose tolerance and insulin resistance
- Thyroid function tests
- Liver function studies to screen for non-alcoholic fatty liver disease
In addition to the above, the following studies are included based on history and physical examination:
- Serum leptin level (recognizing that a genetic mutation lowers leptin level leading to decreased satiety)
- Adrenal function tests (recognizing that cortisol levels are commonly elevated in patients with obesity) to assess possibility of Cushing’s syndrome
- Karyotype with florescence in situ hybridization (FISH) for Prader-Willi syndrome
- Growth hormone secretion and function tests
- Assessment of reproductive hormones, including prolactin
- Serum calcium, phosphorus, and parathyroid hormones to evaluate for suspected pseudohypoparathyroidism
- MRI of the brain, with focus on the hypothalamus and pituitary
(Schwarz, 2020; AACC, 2022)
CASE
Kevin, Age 7
Kevin was screened for overweight and obesity at school. He and his parents were referred to the nurse practitioner for assessment because he had a steadily increasing BMI over the past six months. At the initial appointment, height and weight were obtained, and BMI was calculated and added to his current chart. He is now in the 92nd percentile, which classifies him as overweight.
In taking a family history, the nurse practitioner learned that Kevin’s mother, age 32, has always been overweight and is constantly dieting to maintain her weight. She is also taking medication for hypertension. Kevin’s father is 33 years old. His weight has been normal all his life and his blood pressure is also normal. Kevin’s maternal grandmother, age 57, is overweight and has type 2 diabetes. His maternal grandfather is 58 and of normal weight; he recently suffered a stroke. Both paternal grandparents are in their late 50s and are of normal weight. The grandfather suffers from angina pectoris. Grandmother is in good health. The nurse discussed Kevin’s increased risk for obesity and comorbidities based on this history.
A review of systems reveals that Kevin enjoys school and has a number of friends he plays with both at school and after school. His mood is most often upbeat. He has no symptoms of diabetes and denies headache or breathing difficulties. He sleeps 8 to 10 hours every night. Kevin denies any abdominal discomfort and reports he has regular bowel movements. He denies any foot, hip, or knee pain. Kevin has no allergies to medications and is currently on no medications.
On physical examination Kevin is a White, well-developed, overly nourished, smiling young boy with a small frame and normal musculature, round trunk, and protruding abdomen. There are no obvious dysmorphic features. He has a normal gait, erect posture, and shows good hygiene.
- Vital signs: within normal limits, BP 105/65
- HEENT (head, ears, eyes, nose, throat): face symmetrical with no abnormalities; eyes, PERRLA, no papilledema; no tonsillar enlargement; thyroid normal; lungs, normal breath sounds; teeth in good condition
- Skin: overall even color; no areas of hyperpigmentation, growths, or striae; normal hair distribution
- Heart: normal heart sounds, regular rhythm, no murmurs
- Lungs clear to A and P
- Abdomen: presence of excess adipose tissue, normal bowel sounds, no evidence of discomfort or tenderness to palpation, no hepatomegaly
- Genitalia: normal for age penis, both testes descended, no hernias
- Extremities: no edema, normal pulses, no deformities, no gait deviations observed
Because Kevin is in the 92nd percentile for BMI and has risk factors (maternal overweight and hypertension and family history of stroke, cardiovascular disease, and type 2 diabetes mellitus), a fasting lipid panel and glucose levels were obtained. Liver function studies were deferred at this time. Fasting blood glucose was 80 mg/dl, cholesterol 150 mg/dl, and LDL 100 mg/dl, all of which were in the normal range.