Takeaways

• Doctor-prescribed weight loss pills scientifically proven to work can help make the journey toward sustainable weight loss more manageable.

• There are three doctor-prescribed weight loss pills available in Singapore: orlistat (Xenical, Alli), phentermine (Panbesy, Duromine, Qsymia), and naltrexone-bupropion (Contrave).

• Orlistat promotes weight loss by inhibiting fat absorption; phentermine by increasing the levels of appetite-regulating neurotransmitters; and contrave by targeting the impulse, reward, and hunger centers in the brain, enhancing satiation.

• There is no one universal "best weight loss pill". While all doctor-prescribed weight loss pills in Singapore are scientifically proven to induce and sustain weight loss, they are not without their respective side effects and contraindications.

• Ultimately, it's important to remember that weight loss pills should be used in addition to healthy lifestyle changes and not in place of. 

“Eat less and move more.” While scientifically sound and (hopefully) well-meaning, such weight loss advice is hardly helpful. Contrary to popular belief, it isn't because people are lazy, weak, or need more willpower when they struggle to lose weight and keep it off. Instead, research shows the body prefers the status quo—and, so, “fights back” against weight loss efforts through a process known as metabolic adaptation. In brief, metabolic adaptation involves various well-documented physiological changes, like a decrease in appetite-suppressing leptin and metabolism-boosting non-exercise activity thermogenesis levels, that make weight loss an uphill battle.

So … if you've seen little success getting closer to healthier BMI values, should you take this as a sign to throw in the towel? Well, no. There is something that may help level your journey toward your weight loss goals (make it feel more like a casual hike up Bukit Timah Hill instead of an arduous climb up Mount Everest). Doctor-prescribed weight loss pills—which are available in Singapore.

Why get "doctor-prescribed weight loss pills" in Singapore?

Now, it’s important to note the keyword: doctor-prescribed. That means you’ll need a doctor’s prescription. These weight loss pills are fundamentally different from those “slimming capsules” you’ve likely seen on online marketplaces.

 Unlike doctor-prescribed weight loss pills, you can't trust these online products to:

• Truly work: Health supplements sold in Singapore are not subject to approvals and licensing by the Health Sciences Authority (HSA). Instead, the obligation falls on dealers to ensure that their product labels do not contain exaggerated or misleading claims—a loophole greed-driven, profit-hungry dealers eagerly exploit. So when a slimming product promises to "burn fats" and "show results in as early as seven to 14 days", you'll never know if these claims are truthful or science-based.

• Be free of banned substances: Some of these online weight loss products may contain prohibited substances. For example, in December 2021, the HSA advised the public to refrain from purchasing “Speedy Slim Capsules” as they found it had high levels of sibutramine, a banned substance that can increase the risk of heart attack and stroke.

• Be safe overall: Some unregulated products may also be adulterated with potent medicinal ingredients. In 2018, the HSA found a weight loss product to contain two undeclared potent medicinal ingredients, ephedrine and pseudoephedrine. The seller’s recommended dosing instructions meant that consumers would have taken more than four times the daily limit for ephedrine. High levels of ephedrine can cause life-threatening adverse effects, like high blood pressure, stroke, seizures, and death, especially in consumers with existing medical conditions.

Doctor-prescribed weight loss pills in Singapore, on the other hand? As they’re used under the close medical supervision of doctors, you can trust that these are weight loss pills that actually work and are safe. Of course, “safe” isn’t entirely synonymous with “free of side effects” … but we’re getting ahead of ourselves.

So, next, let's dive into the various doctor-prescribed weight loss pills available in Singapore: how they work, their side effects, and how long you can expect to take them.  

Orlistat (Xenical, Alli)

Orlistat—registered under the trade names of Alli and Xenical—blocks lipase, the enzyme responsible for breaking down fats in your diet. This decreases the amount of dietary fat absorbed in your intestines by approximately 30%, promoting weight loss. In a 2006 randomized controlled trial published in The Annals of Pharmacotherapy, researchers found that participants given orlistat lost significantly more weight (3.05 kg or 6.72 lb) than placebo-treated participants (1.9 kg or 4.19 lb). In most cases, orlistat should result in a 5% weight reduction within three months.

Due to the nature of its action, most side effects of Xenical and Alli are mild and gastrointestinal-related, including:

• Diarrhea

• Flatulence

• Leakage of oily stools

• Stomach pain

 Rare cases of severe liver injury have been reported. Also, since orlistat reduces the absorption of fat-soluble vitamins, individuals prescribed this weight loss medication may need to take multivitamin supplements once daily. Orlistat is FDA-approved for up to two years of continuous usage.

Phentermine (Panbesy, Duromine, and Qsymia)

Phentermine is an anorectic agent (i.e., an agent that suppresses appetite). The exact mechanism through which phentermine reduces appetite remains unclear. However, a leading theory is that it increases the levels of neurotransmitters—specifically, norepinephrine, serotonin, and dopamine—in the brain. This, in turn, promotes a sense of fullness. Phentermine is available in Singapore under three brand names:

• Panbesy

• Duromine

• Qsymia

By the way: those who make frequent trips across the Singapore-Malaysia causeway to stock up on allergy medicines may also come across a weight loss pill called Adipex-P. This is another phentermine brand name (only it's not available in Singapore).

Panbesy and Duromine are phentermine-only formulations. Qsymia, on the other hand, contains a combination of phentermine and topiramate, a drug that has been used on its own to treat seizures but also appears to exert appetite-reducing properties. Research shows that the average weight loss seen with phentermine-only formulations is 3% of initial body weight after three months and 5-7% after six months.

Promisingly, there’s evidence showing that combining phentermine and topiramate may result in even better weight loss results. A 2013 randomized controlled trial published in Obesity found that a higher percentage of participants who’d taken a combination of phentermine and topiramate achieved at least 5% of weight loss after 28 weeks compared to those who’d only taken the monotherapies (i.e., either only phentermine or topiramate). Although the FDA approved phentermine for short-term use of fewer than 12 weeks, healthcare professionals often prescribe the weight loss drug for more extended use.

Drooling at phentermine's weight loss effectiveness? You might wish to tamper your enthusiasm. Of all the doctor-prescribed weight loss pills available in Singapore, phentermine comes with some of the most worrying side effects:

• Cardiovascular complications: Strokes, arrhythmias (i.e., irregular heartbeat), heart failure, coronary artery disease, valvular abnormalities, and uncontrolled high blood pressure

• Uncomfortable symptoms: Tingling or pin-like sensation in hands or feet, dry mouth, insomnia, nervousness, insomnia, and constipation

• Fetal abnormalities: Phentermine is often associated with fetal abnormalities in pregnant women, such as cleft palate. 

• Addictive risk: Given phentermine’s structural similarity to amphetamine, it carries an addictive risk.

Naltrexone-bupropion (Contrave)

Naltrexone-bupropion, available in Singapore as “Contrave”, is a mix of two medications:

• Naltrexone (an opioid antagonist): Used to treat alcohol and drug dependence

• Bupropion (a dopamine and norepinephrine reuptake inhibitor): Used to treat depression or help people quit smoking

While the exact neurochemical effects of Contrave leading to weight loss are not fully understood, scientists believe it targets the brain's impulse, reward, and hunger centers—helping individuals feel less hungry or more satiated sooner. So is this effective in inducing weight loss? Three 56-week clinical studies say yes:

• 2010 study published in Lancet:

  • Contrave group: Lost an average of 5.4% of their baseline body weight

  • Placebo group: Lost an average of 1.3% of their body weight

• 2011 study published in Obesity:

  • Contrave group: Lost an average of 8.1% of their baseline body weight

  • Placebo group: Lost an average of 4.9% of their body weight

• 2013 study published in Diabetes Care:

  • Contrave group: Lost an average of 3.7% of their baseline body weight

  • Placebo group: Lost an average of 1.7% of their body weight

 What about the side effects of Contrave? Well, that may include:

• Nausea

• Constipation

• Headache

• Vomiting

• Dizziness

• Increased blood pressure and heart rate

• Liver damage

• Glaucoma

• Increased seizure risk

• Increased suicidal thoughts

Anyone with a seizure disorder, uncontrolled hypertension, opioid use, or who is pregnant should not take Contrave. Contrave is meant to be taken as a long-term treatment.

Which is the best weight loss pill in Singapore?

Orlistat, phentermine, and naltrexone-bupropion … which is the best weight loss pill? Unfortunately, there’s no clear answer. As covered in this article, all three types of doctor-prescribed weight loss pills available in Singapore are associated with side effects—and, as a result, have different contraindications. Plus, to make things more complicated, research also shows that there's no one universal best weight loss pill for everyone. In other words: what works for others may not work for you. 

Don’t just rely on weight loss pills

Also, once you find one that works for you, weight loss pills are not a substitute for lifestyle changes. In all clinical studies, they have been shown to work best as part of a broader medical weight loss program that includes healthier nutritional habits and a commitment to regular physical activity. Bottom line? If you wish to see those numbers decrease on the scale successfully, weight loss pills should be in addition to lifestyle changes, not in place of them.

 

While this article has focused solely on doctor-prescribed, FDA-approved weight loss pills available in Singapore, please note that they are not your only option. For example, an injectable weight loss medication available in Singapore, liraglutide (brand name: Saxenda), may better suit your needs. Plus, there's also the possibility that you may have an underlying health condition, like hypothyroidism, Cushing’s syndrome, and polycystic ovary syndrome (PCOS), that needs addressing first before you can lose weight. To that end, if you've tried losing weight without seeing much success, consider scheduling an appointment with your doctor.

 

Wish to explore all your weight loss options? Looking for more guidance on the lifestyle changes you should be making—and how to implement them in your daily life to finally lose weight? NOVI Optimum Plus can help. Book a consultation with our doctors here to discover what could be barring you from losing weight and whether weight-loss medications are right for you.