If you have been anywhere near Nigerian social media recently, you have probably heard about the weight-loss injections everyone is talking about.
From celebrity transformations to stories of losing several kilograms in a few months, these medications have become hard to ignore.
But behind the before-and-after pictures sits a more important question:
What actually happens to your body and your nutrition when a medication sharply reduces your appetite?
The answer is more nuanced than “these injections are a miracle” or “these injections are dangerous.”
These medications can be highly effective for people living with obesity, or with overweight and related health conditions. But losing weight is not the same as being well nourished. When you eat much less, what you eat matters even more.
First, what are these medications?
The injections in question contain either semaglutide or tirzepatide. Semaglutide mimics a gut hormone called GLP-1. Tirzepatide acts on both the GLP-1 and GIP hormone pathways.
These hormones influence appetite, food intake, blood sugar and how quickly the stomach empties. The effect people notice most is that they simply feel less hungry, and that is a big reason these drugs can produce substantial weight loss.
A quick note on licensing, because it causes confusion. Both molecules are used to treat type 2 diabetes, and both are also available in products and doses designed specifically for weight management. The weight-loss trial results below come from the weight-management doses. In practice, diabetes-licensed products are also widely used off-label for weight loss.
The trial results are impressive:
- STEP 1: adults with overweight or obesity who took weekly semaglutide 2.4 mg alongside lifestyle support lost an average of 14.9% of their body weight over 68 weeks, compared with 2.4% on placebo (1).
- SURMOUNT-1: participants taking weekly tirzepatide lost an average of about 15%, 19.5% and 20.9% at three different doses over 72 weeks, compared with 3.1% on placebo (2).
So the headline claim holds up. These drugs work, on average, better than any weight-loss medication we had before.
But those are averages from carefully supported trial participants. Individual results vary, and some people lose much less or stop treatment because of side effects.
Losing weight is not the same as losing only fat
When someone says, “I lost 15 kg on this injection,” the instinct is to celebrate the number on the scale.
But the scale cannot tell us what was lost.
Weight loss can include body fat, lean tissue (muscle and other non-fat mass) and water. Some loss of lean mass is common with substantial weight loss, whether it comes from diet, exercise, medication or surgery. In a body-composition substudy of STEP 1, lean mass made up roughly a third to 40% of the weight lost (1,3).
That does not mean muscle is being “destroyed.” Some of that lean mass is water and organ tissue, and some loss is a normal part of getting smaller. But it does mean the goal should change.
Not: “How fast can I make the number go down?”
But: “How can I lose excess body fat while protecting muscle, meeting my nutritional needs and improving my health?”
The appetite effect is both the benefit and the challenge
Picture what happens when your appetite drops dramatically.
You might go from three meals and snacks to two small meals. You might feel full after a few bites. You might skip breakfast because you are simply not hungry. Foods you once loved might stop appealing to you.
For someone with excess weight, that can be helpful.
But there is a catch.
Eating less does not automatically mean eating well.
When you eat much less, there is less room for nutritional mistakes. Every meal has to work harder.
Where does protein come in?
Protein deserves special attention.
When you lose weight, your body does not draw only on stored fat. Some muscle can go too. Eating enough protein and doing resistance exercise are thought to help limit this loss. Most of that evidence comes from weight loss in general rather than from trials of these specific drugs, and research in people using GLP-1-based medications is still developing (3,4).
This does not mean you should live on protein shakes.
It means the smaller amount of food you can manage should still deliver enough good-quality protein for your individual needs. A dietitian or doctor can help you work out what that looks like for you.
In a Nigerian diet, good options include eggs, fish, chicken, beans, lentils, yoghurt, milk and soy products.
What about vitamins and minerals?
When appetite falls, total food intake falls too. That can make it harder to meet your needs for nutrients such as iron, calcium, vitamin D, vitamin B12 and folate, especially if your diet was not varied to begin with (3,4).
This does not mean everyone on these drugs will become deficient.
It means nutritional adequacy deserves attention, particularly if you have very strong appetite suppression, very rapid weight loss, a restrictive eating pattern or ongoing digestive symptoms.
Then there are the digestive effects
Nausea.
Vomiting.
Diarrhoea.
Constipation.
Feeling full very quickly.
These are among the most commonly reported side effects (1,2). They are often mild and settle over time, but they can make it harder to eat and drink enough.
Do not dismiss them as “just part of losing weight.” Persistent or severe symptoms should be discussed with the healthcare professional who prescribed the medication.
Some warning signs need prompt medical attention: severe or persistent abdominal pain (possibly spreading to the back), repeated vomiting that prevents you keeping fluids down, or pain in the upper right abdomen. These medications carry a risk of pancreatitis and gallbladder problems, and they are not suitable for everyone. For example, they should not be used by people with a personal or family history of medullary thyroid cancer, or a condition called MEN2 (5). This is one more reason a proper medical assessment comes first.
Does this mean these medications are bad?
No.
For appropriately selected patients, these medications offer real, well-documented benefits.
The problem is not the drugs. The problem begins when a medical treatment becomes a social media shortcut.
There is a big difference between someone with obesity who is prescribed a medication as part of comprehensive care, and someone buying an injectable online because they want to drop a few kilograms before an event.
There is also a safety issue specific to buying these products informally. NAFDAC alerted the public to falsified semaglutide pens circulating in Nigeria in January 2024, and the World Health Organization later issued its own global alert on falsified semaglutide products (6). Fake pens may contain none of the active ingredient, or something else entirely. If you are prescribed one of these medications, get it from a licensed pharmacy.
A prescription does not replace the need for medical assessment. And no medication replaces the need for nutrition.
So, what should you eat while taking a GLP-1 medication?
Not very little just because the medication has already reduced your appetite.
Instead, make the food you can eat count.
Prioritise protein, vegetables and fruit, fibre, enough fluids and healthy fats. And remember that weight management is not only about food: resistance and strength training can help protect your muscle.
Most importantly:
Do not confuse having little appetite with having no nutritional needs.
Your body still needs protein, vitamins, minerals, essential fats, fibre and fluids even when you are not hungry.
What happens when you stop?
One more point that rarely makes it onto social media. Follow-up data from these trials show that many people regain a large share of the weight after stopping treatment (7,8). The medication changes your appetite while you are taking it, but it does not teach you new eating habits.
That is why the habits you build during treatment (what you eat, how you move, how you plan meals) matter well beyond the prescription.
The bigger question
These medications have changed the conversation about weight management. For many people, they are an effective medical tool.
But the excitement can make us fixate on one number:
How many kilograms did you lose?
A better question is:
What kind of health did you gain along the way?
Did you hold on to your muscle?
Are you eating enough protein?
Are you getting enough fibre, vitamins and minerals?
Are you drinking enough?
Are you staying active?
Are your digestive symptoms being managed?
And are you using the medication under proper medical supervision?
Weight loss can be an important health goal. But nutrition should not become collateral damage.
These medications can help reduce your appetite and your weight. They cannot, on their own, build a balanced plate, protect your muscle, fix an inadequate diet or teach you how to nourish your body.
The injection may change how much you want to eat. What you choose to eat still matters.
References
1. Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183
2. 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
3. Almandoz JP, Wadden TA, Tewksbury C, et al. Nutritional considerations with antiobesity medications. Obesity (Silver Spring). 2024;32(9):1613-1631. doi:10.1002/oby.24067
4. Mozaffarian D, Agarwal M, Aggarwal M, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Am J Clin Nutr. 2025.
5. Prescribing information for semaglutide and tirzepatide (boxed warning on thyroid C-cell tumours; warnings on pancreatitis and gallbladder disease). Available from the manufacturers and from regulators such as the U.S. FDA and the European Medicines Agency.
6. World Health Organization. Medical Product Alert N°2/2024: Falsified semaglutide. Geneva: WHO; June 2024. See also NAFDAC public alert on falsified semaglutide pens, January 2024.
7. Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes Obes Metab. 2022;24(8):1553-1564. doi:10.1111/dom.14725
8. Aronne LJ, Sattar N, Horn DB, et al. Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity: the SURMOUNT-4 randomized clinical trial. JAMA. 2024;331(1):38-48. doi:10.1001/jama.2023.24945