Weight Loss
– GLP-1 & Medical Weight Management
The treatment plan is built from the assessment. Not before it.
Most patients who come to Noumena for weight loss have already tried the obvious things. They’ve cut carbs, joined a gym, used a tracker. Some of it worked for a while. Most of it didn’t last — and the reason is rarely motivation. It’s that the underlying physiology hasn’t been properly addressed.
Weight that resists change is not simply about eating too much. It is about insulin sensitivity, sleep quality, stress hormones, muscle mass, medications, and hormonal shifts that accumulate over time. For the right patient, it is also about treatment options that have substantially changed what medical weight loss can achieve.
Dr Tan begins with a full medical assessment to understand what is actually driving the weight. The treatment plan follows from that. Treatment options include pharmacological options such as GLP-1 receptor agonists where clinically appropriate. But equally important and often overlooked is what comes after.
At Noumena Medical, weight maintenance is planned from the outset — not as an afterthought — because losing weight and keeping it off are two different challenges, and both require a proper plan.
Weight management at Noumena is grounded in clinical obesity medicine — an approach informed by Dr Tan's ongoing engagement with the Singapore Association for the Study of Obesity.
Why Weight Loss is a Medical Issue
The body regulates weight through a complex set of hormonal and metabolic signals. When these are disrupted — by insulin resistance, hormonal change, thyroid dysfunction, cortisol dysregulation, poor sleep, or the cumulative effect of years of metabolic strain — the standard advice of eat less and move more won’t work.
Several factors commonly converge in patients who find weight loss difficult:
- Insulin resistance — cells become less responsive to insulin, driving fat storage particularly around the abdomen
- Hormonal change — both menopause and ADAM involve shifts in oestrogen and testosterone respectively that accelerate fat gain, reduce muscle mass, and make weight harder to shift. These changes are often gradual enough to go unrecognised as a driver of weight gain
- Sleep disruption — elevates cortisol and ghrelin, the hunger hormone, while suppressing leptin, which signals fullness
- Medications — several commonly prescribed drugs contribute to weight gain as a side effect
- Reduced muscle mass — lowers resting metabolic rate, making it progressively harder to maintain weight even without eating more
- Thyroid dysfunction — an underactive thyroid slows metabolism and is a common and underdiagnosed contributor to stubborn weight
Instead of a character flaw, we look at it as physiology. And physiology responds to the right clinical intervention in a way that willpower alone cannot replicate.
Understanding which of these factors is at play — and to what degree — is the purpose of the assessment.
The Assessment
Before any treatment plan is built, Dr Tan conducts a full medical assessment. This is not a weigh-in and a BMI calculation. It is a clinical workup designed to understand the specific physiological picture driving the weight. As a member of the Singapore Association for the Study of Obesity, Dr Tan brings a grounded clinical perspective to weight management.
The assessment can cover the following:
- Body composition — fat mass versus lean mass, visceral fat distribution
- Insulin and glucose handling — fasting insulin, HbA1c, glucose tolerance
- Hormonal status — relevant hormonal panels depending on age, sex, and symptoms
- Thyroid function — TSH and where indicated, a fuller thyroid panel
- Lipid profile — cardiovascular risk in the context of weight
- Medications review — identifying any current medications contributing to weight gain
- Sleep and lifestyle factors — sleep quality, stress, activity patterns
The same set of medical tests is not administered to every patient. At Noumena Medical, we strive to ensure that the rationale for every test is targeted and always transparent to the patient.
GLP-1 & Pharmacological Treatment
GLP-1 receptor agonists — a class of medications that includes semaglutide and tirzepatide — work by reducing appetite, slowing gastric emptying, and improving insulin sensitivity. For appropriate candidates, the results are meaningful: typically, fifteen to twenty percent of body weight over the course of a structured programme, alongside improvements in glucose handling, blood pressure, and cardiovascular risk markers.
These are prescription medications with a specific clinical profile. They are not appropriate for every patient, and the conversation about whether they suit you — which agent, at what dose, for how long — is the consultation itself. Dr Tan discusses the evidence, the realistic outcomes, the side effects, and the cost with each patient individually.
GLP-1 medications work best when the assessment has identified them as the right tool for the right patient, and when they are used alongside the nutritional and activity guidance that supports their effect. Dr Tan reviews progress at intervals appropriate to your treatment and adjusts accordingly. Beyond GLP-1 medications, there are also a range of other treatment options which can be considered.
Maintenance
Losing weight is the first phase. Keeping it off is the longer one.
Most patients who lose significant weight on GLP-1 medications regain a portion of it if they stop abruptly — this is well-documented and worth understanding before starting. The medication is suppressing appetite signals that return when treatment stops. This is not a failure of the treatment; it is how the physiology works.
Maintenance is planned from the outset at Noumena Medical — not as an afterthought. Depending on your response and your goals, this may mean lower-dose continuation, structured tapering, or a transition to lifestyle-based maintenance with ongoing monitoring. The right path is individual and is part of the conversation from the first consultation.
The goal is not a number reached and then abandoned. It is a stable, sustainable result — and the plan that gets you there and keeps you there.
Frequently Asked Questions
What are GLP-1 medications, and how do they work?
GLP-1 receptor agonists are prescription medications that mimic a hormone naturally released in the gut after eating. They slow gastric emptying so you stay full longer, reduce appetite signals in the brain, and improve insulin response to food. The result is a meaningful reduction in hunger — not through willpower, but by directly acting on the hormonal systems that regulate appetite. This is why they work when other approaches have not.
How much weight can I expect to lose?
More than with lifestyle changes alone — and results vary by medication. In clinical trials, semaglutide produced average weight loss of around 15% of body weight over 68 weeks;1 tirzepatide, the newer dual-action agent, produced around 20–21% in the SURMOUNT-1 trial.2 The first head-to-head trial comparing the two, SURMOUNT-5, confirmed tirzepatide’s greater efficacy, published in the New England Journal of Medicine in 2025.3 Individual results vary, and the assessment before starting helps establish what is realistic for you.
- Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight and obesity. N Engl J Med. 2021;384(11):989–1002. DOI: 10.1056/NEJMoa2032183. PMID: 33567185.
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205–216. DOI: 10.1056/NEJMoa2206038. PMID: 35658024.
- Aronne LJ, Bade Horn D, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity. N Engl J Med. 2025;393(1):26–36. DOI: 10.1056/NEJMoa2416394. PMID: 40353578. Published 11 May 2025.
Will I regain weight when I stop?
This is one of the most important questions to ask before starting, and the honest answer is: probably some, without a plan. The medications work by altering appetite hormones — when stopped abruptly, appetite often returns. This is planned for from the beginning at Noumena Medical, not addressed as an afterthought. Maintenance options include lower-dose continuation, structured tapering, and the lifestyle changes that support either path.
What about muscle loss on these medications?
Weight loss of any kind — dietary, surgical, or pharmacological — involves some reduction in lean mass alongside fat. Clinical trial data shows that both semaglutide and tirzepatide reduce fat substantially more than lean mass, with tirzepatide showing more favourable body composition outcomes. For men, pairing the medication with resistance training and adequate protein intake substantially mitigates lean mass reduction — this is part of the plan we build, not an afterthought.
How do I know if I'm a suitable candidate for the GLP-1 medication?
GLP1 are medications that are indicated for the treatment of obesity and a patient’s Body Mass Index (BMI) is used to diagnose obesity. Using BMI calculations, obesity by the standard global threshold is a BMI ≥ 30, or BMI ≥ 27 with at least one comorbidity. For the Asian-adjusted threshold, BMI ≥ 27.5, or BMI ≥ 25 with qualifying health issues.
How long is a typical course of treatment?
It depends on the severity of the condition (obesity). Being able to achieve a target weight is the first and easiest part of the journey while maintenance is the longest and most difficult part. Hence, maintenance strategies is one important topic Dr Tan will discuss during consultation as you approach your target weight.
How often will I need follow-up appointments or monitoring?
Every patient’s weight loss journey is different. So, the frequency of the follow-up can range between a monthly review to every 3 months. The most important factor is that the medication is dosed appropriately and the weight loss and maintenance is managed correctly.
Are these weight management medications covered by insurance or Medisave?
No.