Pharmacotherapy for Obesity Management

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This tool aims to help family physicians and primary care nurse practitioners manage obesity with pharmacotherapy in adult patients. It was designed to help guide discussions and decision-making between providers and their patients. While a comprehensive approach is outlined, the focus of this tool is pharmacological management. 

Important considerations for primary care clinicians
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Important considerations for primary care clinicians1-3

  • Evaluate your attitudes (and those of clinic staff you may work with) towards obesity and recognize that weight bias can affect patient behaviour and outcomes. Consider using the Harvard Implicit Test and Ontario Dieticians in Public Health resources to assess and address weight bias.
  • Understand that patients may come with their own internalized weight bias that may take time to overcome. Assess patient perceptions of weight, considering cultural and socioeconomic contexts.
  • Assess the office environment. Consider different ways to improve the patient experience such as access to bariatric chairs, chairs without armrests, accessible spaces, weight management as an online booking option, etc.
  • Obtain patient consent before discussing weight issues and inform them about the health risks of obesity and central adiposity.
  • Understand the importance of the patient-provider relationship and the time it may take to develop trust. Use non-judgmental language, images and practices. Refrain from assuming health concerns are related to body weight. Consider using Obesity Canada’s People First Language and Obesity UK’s Language Matters: Obesity resources.
  • When discussing weight management strategies, ensure a patient-centered approach is used to develop a personalized and sustainable action plan. It is important to customize the program to fit the patient’s preferences, fitness level (e.g., pedal devices, chair-based exercises, etc.), health status and lifestyle. Consider using the following resources from Obesity Canada, RxFiles and Exercise is Medicine Canada.
  • Consider non-weight goals (e.g., comorbidity management, quality of life etc.) rather than exclusively focusing on weight loss targets.
  • Consider using devices to assist in assessment/management where appropriate (e.g., dynamometers, smart scales, etc.).
  • Offer follow-ups and information regarding the benefits of weight loss for patients not ready to make changes. Clarify that obesity is a chronic medical condition with specific health implications rather than a matter of appearance.
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Assessment

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Initial assessment1-5

Use clinical judgement to decide when to take measurements. With a patient’s permission, measure height and weight to calculate body mass index (BMI). For patients with BMI below 35 kg/m²:

  • Mitigate discomfort or stigma by encouraging self-measurement of waist circumference and calculation of waist-to-height ratio to assess central adiposity.  
    • Utilize waist-to-height ratio in addition to BMI to estimate central adiposity and predict health risks such as type 2 diabetes, hypertension, or cardiovascular disease. Refer to NICE Box 1 Method (pg. 66). Advise patients with increased health risks to seek further assessments (e.g., cardiometabolic risk factor assessment).
Resources

*toolkit download is free. A license form is required for download.

Talking tips
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How to approach weight management conversations2,4

  • “Is it okay if we talk about your weight?”
  • “Are you concerned about the effects of your weight on your health or quality of life?”
  • “Do you feel ready to start treatment?” 
  • “What do you know about your options for treatment?” 
  • “Would it be okay if we helped?” 
  • “How important is it to you to change your weight?” 
  • “What are your goals; over what timeframe?”
  • “How can we achieve these together?” 
  • “How confident are you that you can take action towards your goal?”

Comprehensive history1-3,5,6

Once the patient’s measurements have been taken, conduct a comprehensive history to identify root causes and assess potential barriers and facilitators to treatment such as: 

  • Take a weight history (e.g., At what age did weight become an issue? Was anything happening at that time, like puberty, menopause, immobility, stress, new medication, etc.?).
  • Understand previous weight loss attempts (e.g., How much weight was lost? How was it lost? Was it re-gained?).
  • Understand presentation of obesity-related symptoms (e.g., shortness of breath, difficulty walking related to knee pain, etc.).
  • Consider screening for disordered eating behaviours (e.g., binge eating, craving related). Consider using questionnaires such as the Scoff Questionnaire, the Binge Eating Disorder Screener (BEDS-7) etc.
  • Consider obtaining relevant laboratory investigations:
    • To examine if there are underlying causes or reason for obesity (e.g., hypothyroidism, etc.).
    • To assess for obesity related risk factors and comorbidities (e.g., A1c for type 2 diabetes, lipid profile (dyslipidemia), hypertension, cardiovascular disease, osteoarthritis, and/or sleep apnoea). Address comorbidities as soon as they are identified; do not delay until weight loss has occurred. Deprescribe where appropriate.
  • Understand lifestyle behaviours (e.g., sleep, eating and physical activity patterns and preferences).
  • Understand willingness, motivation and capacity to change lifestyle factors.
  • Consider psychosocial distress and psychological problems (e.g., anxiety, depression, etc.).
  • Address medical problems and medications that may affect weight.
  • Consider environmental, social and family factors (e.g., family history of overweight and obesity).
  • Advise on potential of weight loss to improve health.
  • Conduct an appropriate physical examination (e.g., assess patient mobility and ability to walk).
  • Consider assessing for osteoporosis and sarcopenia in older/frail adults as necessary. Consider weight loss when the benefits outweigh potential risks.

Practice point: Given that weight and obesity assessment can be an overwhelming task for providers, Obesity Canada’s 4Ms framework aims to provide structure to assessment and can be used as a practical approach to understanding barriers, facilitators and complications for patients.

Overweight and obesity interpretations1-3,5-7

Consider using the Edmonton Obesity Staging System (EOSS) to determine obesity severity and guide treatment decision-making. The EOSS is a 5-stage obesity classification system that has been shown to better predict all-cause mortality (compared to BMI or waist circumference measurements alone) by evaluating metabolic, physical, and psychological factors. 

CAUTIONS:

  • While BMI is a proxy measure of body fat and is commonly used to classify obesity and qualify patients for medical insurance coverage, interpret results with caution as it is not a direct measure of central adiposity. BMI is just one of many measurements (e.g., waist circumference, waist-to-height ratio, percentage weight loss, etc.) and should be considered within the context of the patient (e.g., muscle mass, age, best weight, history, goals, etc.).  
  • Be mindful of adults with high muscle mass, as BMI may not accurately reflect central adiposity in this group. 
  • For individuals aged 65 and older, interpret BMI cautiously, considering comorbidities, conditions affecting functional capacity, and the potential protective benefit of having a slightly higher BMI in older age. Evaluate waist circumference in conjunction with BMI when diagnosing obesity. 
Overweight and obesity BMI classifications1,3,7

Classification

Caucasian, Europid and North American:

South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean:*

Healthy weight

BMI 18.5 kg/m² to 24.9 kg/m²

BMI 18.5 kg/m² to 22.9 kg/m²

Overweight

BMI 25 kg/m² to 29.9 kg/m²

BMI 23 kg/m² to 27.4 kg/m²

Obesity class 1

BMI 30 kg/m² to 34.9 kg/m²

BMI 27.5 kg/m² or above

Obesity class 2

BMI 35 kg/m² to 39.9 kg/m²

Threshold generally reduced by 2.5 kg/m²

Obesity class 3

BMI 40 kg/m² or more

Threshold generally reduced by 2.5 kg/m²

 

Practice point3: Exercise clinical judgement when evaluating the healthy weight category, as individuals in this category may still have central adiposity. 

Central adiposity classifications3:

Healthy central adiposity

waist-to-height ratio 0.4 to 0.49 (no increased health risks)

Increased central adiposity

waist-to-height ratio 0.5 to 0.59 (increased health risks)

High central adiposity

waist-to-height ratio ≥ 0.6 (further increased health risks)

These central adiposity classifications can be used for individuals with a BMI < 35 kg/m², regardless of sex, ethnicity, or adults with high muscle mass. Health risks linked to elevated levels of central adiposity include type 2 diabetes, hypertension, and cardiovascular disease. Encourage patients to keep their waist-to-height ratio under 0.5 (waist at least half their height).

Waist circumference5

A WC ≥ 102 cm (in men) or ≥ 88 cm (in women) indicates an increased risk of visceral adiposity and of developing cardiometabolic comorbidities.

For adults with a predominant South Asian, Southeast Asian, or East Asian ethnicity, a lower cut-off for WC (≥ 85 cm in men and ≥ 75 cm in women) applies. 

*Individuals with South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean family backgrounds are more susceptible to central adiposity and have a higher cardiometabolic risk at lower BMI levels.

Referral2,3

Consider referral to specialist weight-management services if:**

  • Assessment of underlying causes of overweight or obesity (e.g., genetic) is needed. 
  • The patient has complex health needs that cannot be managed in primary care settings (e.g., additional support for people with learning disabilities). 
  • Conventional treatment (general primary care practice) has not been successful. 
  • Drug treatment is being considered for a patient with a BMI > 50 kg/m². 
  • Specialist interventions (e.g., nutritionist, psychologist) may be required. 
  • Surgery is being considered. 

** May vary based on clinician experience and comfort level

Resources

Management

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Initiating pharmacotherapy2,3,6,8-10

Consider initiating pharmacotherapy in individuals with BMI ≥ 30 kg/m² or BMI ≥ 27 kg/m² with at least one weight-related comorbidity (e.g., hypertension, type 2 diabetes, dyslipidemia, obstructive sleep apnea, metabolic dysfunction-associated steatotic liver disease [MASLD]), in conjunction with lifestyle and psychological interventions. Pharmacotherapy should be considered:

  • After implementing and evaluating dietary, physical and behavioural interventions.
  • For patients who have not achieved their best weight or reached a plateau despite lifestyle modifications.
  • After discussing the potential benefits and limitations of the medication (e.g., side effects) with the patient.

Engage the patient in the decision-making process when selecting a medication. Consider the patient’s:

  • Readiness to commit to likely long-term medication use. Ensure patients understand the importance of continued lifestyle management while taking these medications and manage medication expectations (e.g., the possibility of weight re-gain if not taken properly).
  • Intrinsic motivation, values and goals. 
  • Circumstances, lifestyle, needs, and preferences.
  • Ability to keep medications refrigerated and ability to administer.
  • Comorbidities and how they impact treatment options.
  • Cost considerations.
  • Access to treatment, monitoring and follow-up.

Specific considerations1,2,7

  • In older adults, consider pharmacotherapy with caution, especially in those with frailty. Consider co-morbidities (e.g., sarcopenia, etc.) and polypharmacotherapy. Continue to encourage consumption of high-quality macronutrient rich foods (with focus on high protein food if deemed medically safe), and physical activity (if deemed medically safe) if considering pharmacotherapy. 
  • Menopause can contribute to abdominal obesity, ultimately increasing the risk of obesity-related health issues; appropriate weight management is advised for menopausal women with obesity. Traditional hormone replacement therapy is not recommended solely for weight loss. 
  • Do not prescribe metformin for gestational weight gain in pregnant women with obesity. Weight-management medications should not be used during pregnancy or breastfeeding. Pre-conception counselling is encouraged.
  • Avoid over-the-counter commercial weight-loss products due to lack of evidence.
  • For patients living with overweight/obesity and other health conditions, consider choosing medications that are not associated with weight gain. 

Pharmacotherapy options11-28

Follow-up and monitoring New

Follow-up1-3,8,10

Conduct regular follow-up appointments to review the effectiveness of lifestyle changes and pharmacotherapy management.

Start with more frequent follow-up visits and transition to long-term monitoring when effectiveness is determined. 

Highlight to the patient that pharmacotherapy for obesity and weight management is long-term and usually for life. These medications may be used to maintain weight, in combination with lifestyle changes, and prevent weight regain.  Stopping these medications may lead to weight regain. Consider setting expectations that consistency is needed but that the journey may change over time and allow for deprescription of medication. 

Practice point2: Remember that pharmacotherapy for obesity and weight management is also new to the patient. It is important to not focus follow-ups solely on weight but also monitor psychological, social (e.g., impact on significant others), movement/activity and nutrition aspects of management. 

Managing plateaus
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Managing plateaus10,29

There are several reasons why patients may experience plateaus in weight loss while using pharmacotherapy. Some include:  

  • Challenges in adherence 
  • Tolerability
  • Barriers to health behaviour change
  • Modulators of weight (e.g., stress, sleep, other medications) 

Strategies for addressing plateaus include: 

  • Framing the importance of health goals (e.g., focus on health and not the numbers on a scale).
  • Focus on the “best weight” (e.g.., weight a person can achieve and maintain while living their healthiest and happiest life) to reduce self-bias and encourage body acceptance.
  • Consider factors that could be impeding weight management efforts or acquisition of treatment goals.
  • Consider other tools such as psychological and behavioural interventions if needed (e.g., address emotional eating, stress management, improve sleep, etc.). Consider referring to patient education resources such as Thames Valley Family Health Team’s Best Weight program or Hamilton Family Health Team’s Weight Science Workshop.
  • Consider changing pharmacotherapy if patient goals are not met.  

 

Monitoring and adjusting1-3,7,10

Monitor pharmacological effects and reinforce lifestyle advice and adherence. Consider maintaining weight loss with pharmacological treatment through shared decision-making rather than continuing weight loss efforts or to prevent weight regain. 

If at least 5% weight loss is not achieved within 3-6 months, using clinical judgement, consider changing, adding or stopping the medication. 

Practice point2: When monitoring weight loss, it is important to monitor the rate of weight loss to ensure it is not at a rapid pace. A loss rate of 0.5-1.0 lbs per week may be appropriate. 

Talking tips
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Talking tips2

  • “Obesity is a chronic disease. Similar to how you may take medications every day to control other chronic diseases, obesity management medications are often long-term or life-long. These medications are not a cure, but they can help to manage this disease.” 

When considering adjusting the dosage, continue to monitor any experienced side effects. Consider a shared decision-making approach when titrating up: 

  • “Are you finding the medication is still effective at your current dose?” 
  • “It is important to understand that the goal is not to stop eating or suppress appetite completely.” 
  • “Are the side effects manageable to continue the medication or increase the dose?” 
  • “Are the side effects making you want to stop this medication?” 

Offer support to patients whose drug treatment is being withdrawn to help maintain weight loss and boost self-confidence if best weight has not been achieved. 

References New

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