Obesity Initial Assessment

Last updated: 19 August 2026
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History

It is important to exclude secondary causes of obesity such as medications, history of genetic or endocrine disorders (eg hypothyroidism, Cushing’s syndrome). Obesogenic medications include antidiabetic agents (eg Insulin, meglitinides, sulfonylureas, thiazolidinediones), antihypertensives (eg alpha-adrenergic blockers, beta-blockers [eg Atenolol, Metoprolol, Nadolol, Propranolol]), antiepileptics (eg Carbamazepine, Gabapentin, Pregabalin, Valproic acid), antidepressants (eg Lithium, monoamine oxidase inhibitors [MAOIs], serotonin and norepinephrine reuptake inhibitors [SNRIs], Paroxetine, tricyclic antidepressants [TCAs]), and antipsychotics (eg Clozapine, Olanzapine, Quetiapine, Risperidone). It is essential to identify potential comorbidities and metabolic risk factors (eg type 2 diabetes mellitus, hypertension, dyslipidemia, OSA, MASLD, cardiovascular disease, OA). Their presence may affect the treatment decisions and outcomes. The patient’s functional status is evaluated through questionnaires for obesity-related disabilities or exercise-testing, and for the presence of sarcopenic obesity.  

Assess the patient’s mental status (eg patient’s self-image, general mental health, stress factors, eating disorder, presence of depression and other mood disorders, substance abuse) and psychosocial barriers. A psychiatric referral is considered if the Patient Health Questionnaire-9 score is ≥10 when screening for depression. It is also important to detect pregnancy in women but is not usually recommended for weight loss programs. Any family history of obesity, cardiovascular disease, hypertension, diabetes mellitus, dyslipidemia, obesity-related cancer, or thyroid disease should also be noted.

Physical Examination

During a physical examination, it is important to measure the patient’s blood pressure in both arms to screen for hypertension, and to check for any evidence of thyroid disease, Cushing’s syndrome, hypogonadism, dysmorphism, and signs of insulin resistance (eg acanthosis nigricans).  

Obesity PEObesity PE


Assess the patient’s mental status (eg patient’s self-image, general mental health, stress factors, eating disorder, presence of depression and other mood disorders, substance abuse) and psychosocial barriers. A psychiatric referral is considered if the Patient Health Questionnare-9 score is ≥10 when screening for depression.  

Anthropometry  

BMI

BMI measures the weight relative to height and is an indirect measure of adiposity. It is calculated by the formula: BMI = weight (kg)/height (m)2. Asian countries have lower BMI cut-off points for overweight and obesity than WHO BMI values.  

BMI can be calculated across the life course; however, in children and adolescents <18 years, weight status should be assessed using age- and sex-specific BMI percentiles or equivalent growth references. BMI may be assessed at least annually for screening and as clinically indicated for risk assessment, management and monitoring of treatment response. It should be used primarily as a screening or surrogate measure of excess adiposity and associated health risk, particularly in population-level assessments and epidemiological studies, rather than as a standalone measure of individual health. Although BMI remains useful for identifying people who may have excess or abnormal adiposity, a clinical diagnosis of obesity should be confirmed by direct body fat measurement or at least one additional anthropometric measure, using age-, sex- and ethnicity-appropriate thresholds. Clinical obesity is diagnosed when excess adiposity is confirmed by direct body-fat measurement or validated anthropometric criteria, together with one or both of the following: Evidence of reduced organ or tissue function attributable to excess adiposity, or significant, age-adjusted limitations in activities of daily living attributable to excess adiposity.

The limitations of BMI usage include the inability to reliably detect or quantify excess adiposity, to differentiate adipose tissue from muscle mass or fluid retention (muscle wasting and hypervolemia are prevalent in heart failure), and to distinguish the location (visceral or subcutaneous) or metabolic consequences of adiposity (central adiposity is strongly related to metabolic dysfunction, inflammation, and cardiovascular mortality), and applicability to diverse populations. 

Waist Circumference and WHR   

Waist circumference and the WHR are useful measurements of intra-abdominal fat content before and during weight loss treatment. Waist circumference is measured at the approximate midpoint between the superior iliac crest and the lower margin of the last rib. The hip circumference is the maximum circumference around the pubic symphysis anteriorly and the point of maximal buttock protrusion posteriorly. WHR is calculated by the formula WHR = waist circumference (cm)/hip circumference (cm).  

They are considered the measurements of choice for classifying central (waist circumference of ≥90 cm for Asian males and ≥80 cm for Asian females) obesity and clinical risk. They are useful for individuals with normal BMI or pre-obesity BMI. Waist circumference and WHR are measured annually for screening. An increased waist circumference is associated with an increased risk for type 2 diabetes mellitus, dyslipidemia, hypertension, MASLD, and cardiovascular disease in patients who may not be considered obese by conventional BMI criteria.

ADULT CLASSIFICATION OF WEIGHT BY BODY MASS INDEX
WHO Classification WHO BMI Cut-off Points (kg/m2) Risk of Comorbidities Asian BMI Cut-off Points (kg/m2)
Underweight <18.5 Low but increased risk of other clinical problems <18.5
Normal 18.5-24.9 Average 18.5-22.9
Overweight/Pre-obese 25.0-29.9 Increased 23.0-24.9
Obese Class I 30.0-34.9 High  25.0-29.9
Obese Class II 35.0-39.9 Very high  30.0-34.9
Obese Class III ≥40.0 Extremely high  ≥35.0
Race High-Risk Waist Circumference (cm) High-Risk Waist-to-Hip Ratio
Men Women Men Women
Asians ≥90 ≥80 ≥1.0 ≥0.85
Caucasians ≥102 ≥88 ≥1.0 ≥0.85


The clinical assessment of obesity requires confirmation of excess or abnormal adiposity by one of the following:

  • Direct body fat measurement, such as dual-energy X-ray absorptiometry (DEXA) or bioimpedance
  • At least one anthropometric criterion: Waist circumference, WHR or waist-to-height ratio, in addition to BMI
  • At least two anthropometric criteria: Waist circumference, WHR, or waist-to-height ratio regardless of BMI
  • Note: Validated methods and age-, gender- and ethnicity-appropriate cut-off points should be used for all anthropometric criteria



The presence of obesity warrants assessment for obesity-related comorbidities (ORCs) which should be graded according to severity if present. The treatment approach and goals are tailored according to the presence of ORCs and their severity. The presence of any ORCs also warrants assessment for obesity and its severity if not the presenting condition or the condition consulted for.