top of page

Drugs for Weight Loss

Should I take medicine to lose weight?

The worldwide prevalence of the number of cases of obesity has tripled since 1975. (1) For weight loss, some will turn to slimming diets, physical activity, surgery and more recently medication. More and more people are turning to the latter alternative. So, they consult their doctor to ask for drugs to lose the weight loss.

To be able to have access to these drugs, the first step should be lifestyle changes in order to lose weight (food, diet, lifestyle, etc.). Then, if that didn't work, the doctor might consider weight loss medication for those with a BMI over 30 or over 27 with an obesity-related disease (high blood pressure, high cholesterol, etc.) ). Moreover, it is imperative for the doctors to check the medical history and since these drugs can have an impact on the health of the patient.

Currently, in Canada, 3 drugs can be prescribed with a doctor's prescription, namely Contrave® (naltrexone and bupropion), Saxenda® (liraglutide) and Xenical® (orlistat) (2).

How do these drugs work?

Contrave (naltrexone and bupropion)

They act on the brain and more specifically on the hypothalamus (appetite regulation center) as well as on the mesolimbic dopaminergic circuit (reward system) to reduce the feeling of hunger (3).

Saxenda (liraglutide) / Ozempic (semaglutide)

This medicinal product contains the hormone GLP-1 (glucagon-like peptide-1) which must be injected with a pre-filled pen. This hormone is naturally produced by the body. It reduces the appetite, therefore naturally reduces the amount of food ingested by the patient (4).

Xenical (orlistat)

This reduces the intestinal absorption of ingested fats (5). So we absorb less energy (Calories) from our fatty foods.


It is true that a person can be healthy despite living in a fat body or living with obesity. On the other hand, excess body fat can impair movement and increases the risk of suffering from heart disease, certain cancers, osteoarthritis, diabetes, hypertension (6), can reduce life expectancy, etc. . (7) Studies have shown that taking these drugs can help weight loss in a large number of people (varies from person to person). By the same token, this reduces the risk of suffering from the diseases named above.


The side effects depend, among other things, on the drug used and the profile of the patient. Here are some possible side effects: nausea, vomiting, diarrhea, constipation, headache, sleep problems, etc. (8).

These medications can also cause malnutrition in many people if they are poorly supported in this weight loss process or if their diet is unbalanced. Malnutrition can result in loss of muscle mass, fatigue, apathy, osteoporosis, etc.

The cost associated with taking medication can be high. It is a monetary cost for the health system.

These drugs may need to be taken for life.

There is a lack of long-term scientific studies on its drugs. These medications are very recent. To date, we do not know the possible long-term side effects.


Finally, several drugs demonstrate positive weight loss effects for a large number of people, but it is important to take into consideration the negative points mentioned above. Furthermore, drugs will never replace a healthy lifestyle. For healthy weight loss, we often have to change our lifestyle habits (diet, physical activity, sleep, etc.). For more answers to your questions, talk to your healthcare professional.

See you next time,

Karine Drouin, Nutr. dt.p.



1- OMS. (Août, 2020). Obésité et surpoids. Retrouvé le 26 mai 2022 au

2- Obésité Canada. (n.d.). Médicaments vendus sous ordonnance. Retrouvé le 5 mai 2022 au

5- Svendsen, M. Helgeland M., Tonstad, S. (2009). The long-term influence of orlistat on dietary intake in obese subjects with components of metabolic syndrome. Journal of human nutrition and dietetics : the official journal of the British Dietetic Association. Retrouvé le 1er mai 2022, en ligne au

6- Association des médecins endocrinologues du Québec. SURPLUS DE POIDS ET OBÉSITÉ. (n.d). Retrouvé le 31 juillet 2021 au

7- Minerva. (2004). L'obésité réduit l'espérance de vie. Retrouvé le 25 mai 2022 au

8- (Mai, 2014). Médicaments d’ordonnance pour la perte de poids. Retrouvé le 25 mai 2022 au

Related Posts

See All


bottom of page