Obesity in Primary Care: Making the Diagnosis

June 12, 2017

Here are answers to the questions primary care physicians most often ask about patient evaluation.

Obesity is a major public health problem with a prevalence in the United States of about 30%. The condition is associated with important chronic diseases, such as type 2 diabetes, hypertension, dyslipidemia, coronary heart disease, stroke, and several cancers, as well as disability and increased mortality.

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The US Preventive Services Task Force (USPSTF) recommends screening all adults for obesity and indicates that health care providers have an important role in preventing, identifying, and managing this chronic disease. The USPSTF also recommends that once a diagnosis has been established, physicians should offer or refer patients with a body mass Index (BMI) > 30 kg/m2 to an intensive, interdisciplinary lifestyle intervention program.

However, obesity is a chronic disease that is underdiagnosed in clinical practice. Fewer than 30% of adults with obesity are thought to receive the diagnosis during their primary care visit. Also, probably because of the failure to obtain anthropometric patient data and to clinically identify obesity in patients with this pathology, only a small percentage of obese persons (37%) received any formal obesity counseling during the first visit to their PCP.

Weight Loss Interventions

The USPSTF found adequate evidence to indicate that intensive, multicomponent behavioral interventions for obese adults can lead to an average weight loss of 4 to 7 kg (8.8 to 15.4 lb). These interventions also improve glucose tolerance and other physiologic risk factors for cardiovascular disease.

The questions primary care physicians most often ask about obesity diagnosis are answered on the pages that follow.

Next: Developmental Factors and Comorbidities

• The first question: Is obesity a disease?

Yes, the American Medical Association defined obesity as chronic disease in 2013. Various factors play a role in disease development: neurobehavioral, genetics/epigenetic, endocrine, medical, pharmacological, environmental, and immune.

The extra accumulation of fat produces adipose tissue dysfunction with important negative consequences for physical, mental, and social health. Obesity is an important metabolic disorder responsible for significant comorbidities-type 2 diabetes, hyperlipidemia, osteoarthritis, depression, obstructive sleep apnea, and heart disease.

• How do I make a diagnosis of obesity?

Obesity is high in prevalence, affecting more than 30% of the US population. That is why primary care physicians should always perform an obesity screening by obtaining the patient’s weight and height and calculating his or her BMI.

Patients with a BMI higher than 30 kg/m2 could receive a diagnosis of obesity, but BMI does not make a distinction between fat and muscle. So it’s important to identify other factors, such as medical problems associated with obesity and whether the patient exercises, to determine whether the patient’s BMI really represents a disease. 

• What about measuring abdominal circumference?

Measuring the abdominal circumference as a surrogate marker of abdominal fat mass would be desirable, especially if the patient’s BMI is below 35 kg/m2. This can help us estimate the presence of visceral obesity, which is known to be an important cardiometabolic risk factor.

Waist circumference correlates with abdominal fat mass and is associated with cardiometabolic disease risk. Men and women who have waist circumferences > 40 in and 35 in, respectively, are considered to be at increased risk for cardiometabolic disease.

Next: The Importance of Staging Obesity

• Is it important to stage the degree of obesity?

Staging obesity is important because it can provide an idea of disease severity and helps us decide what kind of treatment we should pursue. Obesity classification traditionally is based on BMI:

Normal weight: BMI, 18.5 to 24.9 kg/m2

Overweight: BMI, 25.0 to 29.9 kg/m2

Class I obesity: BMI, 30.0 to 34.9 kg/m2

Class II obesity: BMI, 35.0 to 39.9 kg/m2

Class III (morbid obesity): BMI, 40 kg/m2 or more

There are other ways to classify patients that similarly correlate with prevalence of metabolic syndrome, such as waist circumference and percentage of fat mass.

• What factors besides medical problems affect a patient’s obesity?

Nutrition: Several points should be assessed, including meal schedule, food quality, and food quantity.

Schedule-Does the patient skip meals? Eat out of home? Snack between meals?

Quality-What kind of food does the patient usually eat: saturated fats, rapid absorption carbs, sodas, juices, fried dishes, fast food, sweets, chips, vegetables, fruit, proteins?

Quantity-Ask about size of the portions the patient eats.

Physical activity: This is a key component of weight loss, so if the patient has a sedentary lifestyle, the goal should be to find a program that can help increase physical activity. For that, it’s necessary to know the patient’s limitations in starting to become more active. Is exercise difficult because the patient has osteoarthritis or dyspnea? Is the patient active in his/her daily routine? Does she/he take the stairs or walk during the day? What kind of work does she/he do?

Next: Stress, Anxiety, and Depression, Oh My

Psycho-emotional factors: Stress, anxiety, and depression are key components of managing obesity efficiently. These 3 factors induce people to eat more and to choose hyperpalatable foods, which usually are less healthy than others.

To gauge how much attention these factors require, you might ask the patient about them and rate each on a scale. If you determine that psycho-emotional factors are a main issue related to the patient’s obesity, refer him/her to a psychologist so the patient can receive specific help regarding ways to deal with stress, anxiety, depression, and eating disorders.

Sleep: Quality and quantity of sleep need to be addressed because both have a strong relationship with stress, depression, anxiety, and hunger. Lack of sleep is associated with increased appetite and chronic fatigue. Also, obstructive sleep apnea causes hypoxia and this is related to insulin resistance, creating a vicious circle by worsening the obesity.

To assess sleep issues, ask the patient about snoring, difficulty with falling sleep or keeping asleep, and headache or tiredness in the morning. If 1 or more of these symptoms are present, order a polysomnogram to rule out sleeping disorders. 

Medications: A patient’s medications list is not always assessed, but a significant number of medications are associated with increased appetite and weight gain:

Diabetes medications: sulfonylureas, thiazolidinediones, meglitinides, insulin

Anticonvulsants: carbamazepine, valproate, gabapentin

Antipsychotics: clozapine, risperidone, olanzapine, quetiapine, haloperidol, quetiapine, perphenazine

Antidepressants/mood stabilizers: amitriptyline, imipramine, trimipramine, nortriptyline, doxepin, tranylcypromine, fluvoxamine, phenylzine, paroxetine, mirtazapine, lithium

Hypertension medications: beta blockers, dihydropyridine calcium channel blockers

Hormones: glucocorticoids, megestrol acetate, progestational steroids, insulin

Others: cyproheptadine, tamoxifen, cyclophosphamide, methotrexate, aromatase inhibitors

Ask patients why they are taking these medications, for how long, and whether they have observed a relationship between taking the drug and gaining weight.

Next: Ruling Out Secondary Causes of Obesity

Endocrine disorders and family history: Secondary causes of obesity may need to be ruled out. These include growth hormone deficiency, hypogonadism, Cushing syndrome, hypothyroidism, hypothalamic damage, and genetic syndromes (Carpenter, Lawrence-Moon-Bield, Cohen, Prader Willy, Alström).

Also address the patient’s family history of obesity, because genetics play an important role in the presence of obesity. In general, patients with obesity have children who also have the disease.


Next in this Special Report: Comorbidities