Pharmacological Treatment for Obesity

Dr. YEUNG Chun Yip

Honorary Consultant in Endocrinology

Specialist in Endocrinology, Diabetes & Metabolism

Why is Obesity Treatment Important?

Obesity is more than a cosmetic issue. It is a serious medical condition that can lead to many other diseases including type 2 diabetes, hypertension and sleep apnea. Obesity also increases the risk of developing different types of cancers. Research has shown that the mortality risk can be increased by 30% with every extra 5kg/m^{2 excess} in Body Mass Index (“BMI”).

Achieving weight loss, on the contrary, can significantly improve health conditions. According to a 10-year Look AHEAD (“Action for Health in Diabetes”) research recruiting over 5,000 participants, the mortality risk of heart diseases and other cardiovascular conditions could drop by 20% if a 10% weight loss was achieved through exercise and dietary changes in the first year.

Registered and Approved Anti-obesity Drugs in Hong Kong

In addition to lifestyle modifications, patients with BMI over 30kg/m² or 27 kg/m² with obesity-associated medical illnesses may consider the use of medical therapy to facilitate weight loss.

The following drugs have been approved and registered in Hong Kong for weight reduction: 

* For short-term use only (less than 12 weeks)

GLP-1 Receptor Agonist

Originally developed and registered for the treatment of type 2 diabetes, selected GLP-1 Receptor Agonist (“GLP-1 RA”) can now be prescribed to obese patients without diabetes to facilitate weight loss. 

As an incretins therapy, GLP-1 RA has the following effects:

1. Delay gastric emptying, making one feel full earlier during meal and eat less;

2. Increase satiety via the appetite control centres in the brain;

3. Stimulate insulin secretion to lower blood glucose levels after meal; and

4. Reduce glucagon secretion, leading to reduced glucose output from the liver

Due to the increase in satiety and reduce in hunger feeling, significant weight loss is noted in most patients using GLP-1 RA. Certain GLP-1 RAs have been approved by the U.S. Food and Drug Administration (FDA”) for use in non-diabetic obese patients, namely liraglutide (the first-generation GLP-1 RA requiring daily injection) and semaglutide (the second-generation GLP-1 RA for weekly injection). Injected at a maximum of 3 mg daily, liraglutide can achieve an average 6% weight loss. For semaglutide, a weekly injection of 2.4mg can reduce weight by 9.6%. In Hong Kong, semaglutide is currently registered for treatment of type 2 diabetes only. 

Common side effects of GLP-1 RA include nausea, vomiting, diarrhoea, constipation, increase in heart rate and low blood glucose level etc. It is still controversial whether GLP-1 RA can slightly increase the risk of developing acute pancreatitis. Patients are advised to discuss in detail with specialists and undergo comprehensive assessment before initiating GLP-1 RA treatment.

Looking Ahead

Oral GLP-1 RA semaglutide has been registered and in use in Europe and the US. And the recently launched Tirzepatide, a dual GIP/GLP-1 receptor agonist, is shown to be more effective than semaglutide in controlling blood glucose level and reducing weight as a weekly injection.

While there are many effective anti-obesity medications, we cannot forget the “BASICS” if we want to achieve the best outcomes. Both diet and exercise are “FUNDAMENTALS” for weight loss and obesity prevention.