More than half of us are carrying more weight than is good for us. The Ministry of Health and Wellness put it plainly in the Jamaica Health and Lifestyle Survey: 53.8% of Jamaicans aged 15 and over are overweight or obese, and 28.6% are obese. Among Jamaican women the combined figure reaches 67.6%.
So when a new class of weight loss medicine arrives, it arrives into a country where the question is not academic.
Most explanations of these medicines start with the drug. This one starts with the hormone, because the drug is a copy of something your body already makes, and once you understand the hormone the rest follows easily.
This article covers how these medicines affect appetite, fullness and body weight. They have other effects in the body that fall outside the scope of this article and belong in a conversation with your doctor.
GLP-1 is a hormone, not a medicine
GLP-1 stands for glucagon like peptide 1. Your gut releases it when food arrives.
That is its job: to tell the rest of the body that food has come in. It is one of a small group of hormones that carry messages from the digestive system to the brain, and it is part of the machinery that decides when you feel hungry and when you feel full.
Everyone reading this already produces GLP-1. It has been working in you since before you read this sentence.
What it does when it is released
Two effects matter most for appetite and weight.
It slows down how quickly the stomach empties. Food stays in the stomach longer, so fullness lasts longer after a meal.
Think about what that means against an ordinary Jamaican plate. Rice and peas, a piece of chicken, fried plantain, maybe a festival or two. A box food eaten fast at midday because the lunch break is short. Sunday dinner, where the portion is an act of love and leaving food is close to an insult. These are meals built around volume, and they are eaten by people whose fullness signal arrives late and fades early.
When the stomach empties more slowly, that same plate registers as too much sooner. Nothing on the plate changed. The timing of the signal did.
It signals fullness to the brain. There are GLP-1 receptors in the parts of the brain that regulate appetite and energy balance. When those receptors are activated, the message that arrives is roughly “enough food has come in”. Research in humans has consistently found that GLP-1 promotes satiety and reduces how much people eat.
Put together: fuller for longer, and less interested in eating in the first place.
The two minute problem
If your body already makes a hormone that reduces appetite, why would anyone need a medicine version of it?
Because natural GLP-1 disappears almost immediately. An enzyme called DPP-4 breaks it down within minutes of release. That is by design. The hormone is a short message about one meal, not a standing instruction, so the body clears it fast.
That is useless as a treatment. A medicine that lasted two minutes would have to be taken continuously.
So the medicines are engineered versions of the same molecule, modified so that DPP-4 cannot break them down quickly and so they bind to proteins in the blood that keep them in circulation. The result is a molecule that does what natural GLP-1 does, but stays active for about a week instead of a couple of minutes.
That single change is why these are once weekly injections rather than something taken with every meal. The weekly schedule is not a convenience feature. It is a direct consequence of how the molecule was rebuilt.
What this feels like from the inside
The clinical description is reduced appetite and increased satiety. What people actually report is more specific.
Meals finish sooner. Portions that once felt normal start to feel like too much. Food that used to be hard to stop eating becomes easier to leave.
Many people also describe something that has no clinical name but that patients have started calling food noise: the constant background stream of thoughts about food. The patty you pass every morning. The bag juice in the cooler. The jerk pan you smell from the road at six o’clock on the way home from work. A frequent report is that this quietens down. There is active research into why, centred on receptors in the brain’s appetite and reward pathways, and it is fair to say the mechanism is not yet fully settled. The experience is reported often enough to be worth naming.
Weight is biology, and we talk about it as though it were character
Weight gets discussed lightly here. Fluffy. Big boned. Healthy looking. The affection in those words is real, and so is the assumption sitting underneath them, which is that body size comes down mostly to what a person chooses.
The biology says otherwise. Appetite is a signalling system, and in some people that system runs differently. These medicines work because they act on the signal, not on the person’s discipline. That is the whole reason a medicine can do something that years of trying often could not.
It is also why weight gets treated as a medical matter rather than a moral one, and why a doctor assesses it rather than a slimming tea seller.
What GIP adds
GLP-1 is not the only hormone the gut releases when food arrives. GIP is another, and it is involved in appetite regulation and in how the body stores fat.
Some medicines act on GLP-1 alone. Semaglutide is the most widely used of those. Others act on both the GLP-1 and GIP receptors at once and are described as dual agonists. Tirzepatide is the one most people will have heard of.
Whether acting on both pathways is meaningfully better than acting on one is covered in a separate article that looks at the trial evidence directly. The short version is that in the one trial that compared them head to head, the dual agonist produced the larger average reduction in body weight, and also the larger reduction in waist circumference.
Waist measurement is worth pausing on here. In the Jamaica Health and Lifestyle Survey, 43.7% of Jamaicans had central obesity, measured at the waist rather than by weight alone, and among Jamaican women the figure was 67.9% against 17.5% for men. Waist is not a vanity measure. It is the one clinicians watch most closely.
What these medicines do not do
This matters as much as what they do, particularly in a market where a great deal is sold on a promise.
They are not fat burners. Nothing in this class increases the rate at which the body burns fat directly. Weight comes off because energy intake falls.
They are not metabolism boosters. That is a different claim, made by a different and far less evidenced category of product, much of which is sold locally without anyone’s name attached to it.
They do not work independently of what you eat. They change how much you want to eat and how full you feel. What you eat during that period still determines a great deal, including how much of the weight lost is fat rather than muscle.
They are not a short course. Obesity behaves as a chronic condition, and the body actively defends a weight it has settled at. Appetite signalling generally moves back towards its previous state when the medicine stops. What that means for any individual, and what a plan for stopping looks like, is a subject to raise with a doctor before starting rather than after.
They are not a substitute for the rest of care. The World Health Organization published its first guideline on this class of medicine for obesity in adults in December 2025, and it is explicit that pharmacotherapy is not a standalone solution and belongs inside a broader programme of supervised care. The Jamaican data says the same thing from another direction: in the national survey, obesity prevalence fell from 35.4% among people with low physical activity to 21.3% among those with high physical activity. Movement is not competing with the medicine. It sits alongside it.
Why the dose starts low and goes up slowly
Because the same slowed stomach emptying that produces fullness also produces the side effects.
Nausea, and sometimes vomiting, diarrhoea or constipation, are the most common effects in this class, and they cluster around the periods when the dose is increasing rather than being spread evenly across treatment. Starting low and stepping up over months gives the digestive system time to adjust at each level.
This is worth taking seriously in Jamaican heat. Vomiting or diarrhoea in a hot climate moves a person towards dehydration considerably faster than the same symptoms would somewhere temperate, and more so for anyone working outdoors, on a construction site, in a hotel kitchen, on the road all day, or through a night shift. If you are on one of these medicines and you are losing fluid, replacing it is not optional, and persistent symptoms are a reason to contact the prescribing doctor rather than to push through. Your doctor will tell you what to watch for and when to call.
This is one of the reasons these medicines are prescribed with ongoing review rather than issued once. Somebody has to be watching how you respond at each step and deciding whether to hold, continue or stop. That ongoing review is the part that distinguishes a medically supervised weight loss program from simply obtaining a medicine.
A word about supply
Availability in Jamaica is not guaranteed and it moves. Supply depends on importation, and a medicine that is theoretically more effective but inconsistently available is not more effective in practice.
This is also why the market for unregulated alternatives exists here, and why it is worth being direct about it. Products sold without a prescription, compounded versions from unverified sources, and anything offered through a direct message are not the same thing as a prescribed medicine from a regulated supply chain, whatever the label claims. A doctor is the right person to tell you what can actually be obtained and prescribed for you.
The short version
Your gut releases a hormone that tells your brain you have eaten. It lasts about two minutes. These medicines are that hormone, rebuilt to last about a week, so the fullness signal is present continuously rather than briefly after a meal.
Everything else follows from that.
Frequently asked questions
Is GLP-1 a natural hormone or a drug? Both, in a sense. GLP-1 is a hormone your gut already produces. The medicines are engineered copies of it, modified to last far longer in the body.
Does it speed up metabolism? No. Weight reduction in this class comes from eating less, driven by reduced appetite and increased fullness, not from burning more.
Why is it an injection rather than a tablet? The molecule is a peptide, and peptides are broken down in the digestive tract. Injecting under the skin bypasses that problem. Oral formulations of some of these medicines exist or are in development, and a doctor is the right person to say what is actually available here.
How long does it take to feel anything? Appetite changes are often noticed within the first weeks, but the starting dose is deliberately low, so the full effect builds over months as the dose increases.
Does it work for everyone? No. Response varies a great deal between individuals, and some people do not respond well or cannot tolerate the side effects. This is one of the things assessment and ongoing review are for.
Do I still need to worry about food and movement? Yes. The national survey found obesity prevalence dropping sharply as physical activity rose, and the WHO guideline is explicit that medicine is not a standalone solution.
Is it available in Jamaica? Availability changes and depends on supply. A doctor is the right person to tell you what can actually be obtained and prescribed for you.
What happens if I stop? Appetite signalling generally moves back towards where it was, and weight regain is common without a plan in place. This is covered in a separate article on stopping.