Weight-loss pills, powders and teas line pharmacy shelves and online stores. Now prescription GLP-1 medicines such as semaglutide are showing much larger effects. That is changing what people expect from weight management.
The size of the problem
WHO reports that in 2024, 2.6 billion adults (45%) were overweight, including 940 million living with obesity [1]. Adult obesity has more than doubled since 1990 [1]. Higher-than-optimal body weight caused an estimated 3.7 million deaths in 2023 [1].
What the evidence says on supplements
The US NIH Office of Dietary Supplements reviewed common weight-loss ingredients, such as green tea extract, garcinia and glucomannan. It says there is little scientific evidence that weight-loss supplements work, and that makers rarely test them in people [2]. NIH notes that Americans spend over US$2 billion a year on them [3]. The US FDA has also found hidden drug ingredients in some products sold as weight-loss supplements [4].
The GLP-1 effect
In December 2025, WHO published a guideline on GLP-1 therapies for adults with obesity. It supports them as one part of long-term care, alongside diet, activity and psychological support [1]. This creates new demand for supplements that support people on these medicines:
- Protein to help keep muscle during weight loss.
- Fibre for gut comfort.
- Multivitamins when people eat much less.
These are support products, not weight-loss treatments. People should talk to their doctor before adding them.
Children and teenagers
Obesity is rising fastest among the young. In 2024, 400 million children and teenagers aged 5–19 were overweight, including 170 million with obesity [1]. The share who were overweight rose from 8% in 1990 to 20% in 2024 [1]. Another 35 million children under 5 were overweight [1].
Big differences between regions
The share of adults who are overweight ranges from 32% in the WHO South-East Asia and African regions to 68% in the Americas [1]. Obesity is now rising faster in low- and middle-income countries and rural areas than in rich cities [1]. Many of these countries face a "double burden": undernutrition and obesity at the same time [1].
The cost
If nothing changes, overweight and obesity are predicted to cost the world US$3 trillion a year by 2030, and more than US$18 trillion a year by 2060 [1]. Obesity raises the risk of type 2 diabetes, heart disease, liver and kidney disease, and several cancers [1].
Why supplements disappoint
Sellers often claim their products block fat or carbohydrates, curb appetite or speed up metabolism [2]. The NIH says there is little scientific evidence that they work [2]. Studies are often small and last only weeks or months [2]. Some products contain hidden drugs that are not on the label [4]. These can be dangerous for people with heart problems or who take other medicines.
What does work
WHO describes obesity as a chronic disease that needs long-term care [1]. Its list of care for adults includes [1]:
- Healthy eating and regular physical activity.
- Good sleep and emotional support.
- Behavioural and nutrition counselling.
- Medicines, including GLP-1 therapies, where suitable.
- Metabolic and bariatric surgery, where suitable.
Policy is moving
Almost 9 out of 10 countries have adopted policy goals to reduce obesity [1]. WHO's Acceleration Plan to Stop Obesity now covers 34 frontrunner countries, home to 1.3 billion people [1]. WHO estimates that healthy-diet "best buy" policies return about 14 times what they cost [1]. These include food labelling, limits on marketing to children and taxes on sugary drinks.
The role of health workers
WHO says health workers should check weight status routinely and spot overweight early [1]. They should give advice on diet, activity and sleep, and check for problems like high blood pressure, diabetes and mental health issues [1]. People with obesity should be offered long-term, person-centred care with regular follow-up [1].
Prevention through life
WHO lists steps that lower the risk of obesity from before birth to old age [1]:
- A healthy weight before and during pregnancy.
- Only breast milk for the first 6 months, and breastfeeding up to 2 years or more.
- Healthy eating, play, good sleep and limited screen time for children.
- Fewer sugary drinks and less food high in fat, sugar and salt.
- Regular physical activity at every age.
WHO stresses that obesity is a responsibility of society, not just of individuals [1]. Food prices, marketing, city design and work patterns all shape what people eat and how much they move.
A US government view
The US Government Accountability Office reviewed weight-loss supplements. It concluded that little is known about whether they work, and that some have been linked to possible physical harm [5]. The NIH advises people to talk to a health provider before trying them, especially if they take other medicines or have health conditions [2]. Health experts agree that diet, fewer calories and physical activity are the basis of lasting weight loss [5].
Key numbers at a glance
- 2.6 billion adults overweight in 2024, 940 million with obesity.
- 1 in 7 people worldwide live with obesity.
- 400 million children and teens aged 5–19 were overweight.
- High body weight caused about 3.7 million deaths in 2023.
- Costs could reach US$3 trillion a year by 2030.
Supplements have not shown they can change these numbers. Long-term medical care and healthier environments can.
What this means
Supplement brands are moving from "fat burner" claims to nutrition support for people on medical weight care. Brands that test for purity and make honest claims will stand out.
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- Get a free sample report or talk to our team
Sources
- WHO fact sheet: Obesity and overweight
- NIH Office of Dietary Supplements: Dietary supplements for weight loss (fact sheet for consumers)
- NIH news release: Will supplements help your workout or diet routine?
- US FDA: Tainted weight loss products
- NIH Office of Dietary Supplements: Dietary supplements for weight loss (health professional fact sheet)
Banner image: Soehnle weighing scale up to 10 kg with a detachable tray 3 by W.carter, CC BY 4.0, via Wikimedia Commons.
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