World Obesity Day 2025 has come and gone on 4 March and coincides with the publication of the World Obesity Atlas 2025, which indicates the status of global and regional prevalence of overweight and obesity.
Global trends in overweight and obesity:
According to present trends, overweight and obesity will affect about 50% of the world population, nearly 3 billion people, by 2030. This trend indicates a continuous global rise when compared with previous statistics, which reflected 36% (1,6 billion people) in 2010 and 40% (2 billion people) in 2015. Compared with 1990, the 2025 findings show that the global prevalence of obesity has increased by 155% in males and 105% in females.
Overweight and obesity are measured in terms of Body Mass Index (BMI). High BMI includes overweight (BMI 25-30 kg/m2)and obesity (BMI 30 kg/m2 and over). BMI is a measure that relates body weight to height and is calculated by dividing weight in kilograms by height in meters squared (kg/m2).
Current trends suggest that by 2030 about 50% of adult men and women will be living with high BMI, while 17% of men and 22% of women will be living with obesity by then. The likelihood of having a high BMI rises with age, which means a significant proportion of the global population will have experienced high BMI during their lifetime by the age of 65 and higher. For the large majority of countries, the maximum prevalence of high BMI occurs in the age range of 40-65 years for men and 40-70 years for women.
These figures are in line with a study by the South African Human Sciences Research Council, conducted between 2021 and 2023, which found that almost 50% of South Africans are overweight or obese.
South African trends in overweight and obesity:
The global rises in the number of adults with obesity is mirrored by the South African portion of the report, where an estimated 32% of adults are living with obesity and 56% of adults are overweight, both drivers of non-communicable diseases.
Another study by the Human Sciences Research Council published in 2022 has indicated that the prevalence of overweight and obesity in South Africa may be influenced by cultural beliefs in some Black cultures. Being overweight is seen as good, healthy, and a sign of prosperity by some, while there is a stigma attached to being thin, with those individuals labelled as being HIV-infected.
Being overweight and obese are considered normal and acceptable in certain cultures. It is believed that when one has money, they can afford to buy food and eat as much as they like, which reflects that they have enough money. Another perception is that mothers are encouraged to eat more for their well-being and that of their infants after childbirth.
- Cardiovascular diseases, including conditions such as heart attacks, strokes, and high blood pressure.
- Cancers, including lung cancer, breast cancer, and colon cancer.
- Chronic respiratory diseases such as asthma, emphysema, and chronic obstructive pulmonary disease.
- Diabetes.
- Mental health disorders.
- Chronic kidney disease.
- Non-alcoholic fatty liver disease.
- Autoimmune conditions.
Implications of the available evidence:
As overweight and obesity is already a major health crisis, this has become one of the top risk factors affecting global health. Surges in obesity among children and adolescents will add to this burden and increase the incidence of various non-communicable diseases. These diseases include the following:
Non-communicable diseases are also known as chronic diseases and are conditions that are not contagious and are not spread from person to person. They result from a combination of genetic, physiological, environmental, and behavioral factors.
According to the World Health Organization, non-communicable diseases are collectively responsible for 74% of all deaths worldwide.
Apart from adverse health outcomes, overweight and obesity have staggering global economic ramifications. In 2019 the estimated total direct and indirect costs associated with obesity ranged from US$3·19 billion in low-income countries to $1·33 trillion in high-income countries. The World Obesity Atlas states that the world is off-track to meet targets to reduce the incidences of non-communicable diseases.
In many countries, especially high-income countries, the rise of obesity is associated with an aging population and a low fertility rate, as well as an increase in the risk of infections, all exerting more pressure on health-care services and expenditures, including a higher demand for elective and costly surgeries.
Many low-income countries have the double burden of malnutrition, with a high prevalence of undernutrition, particularly among children.
In the past three decades Asia and Africa have seen the largest percentage increases in obesity in the world.
Main causes of overweight and obesity:
- Poor diet: The consumption of foods that are high calorie, high-fat (of the unhealthy type), high-sugar, highly refined, and the consumption of sugary drinks are on the rise. Traditional diets composed of staple grains, fruits, and vegetables have ongoing shifted to diets dominated by unhealthy and highly processed packaged food. In addition, the close collaboration between chain food retailers and large food manufacturers has increased over time and often results in the promotion of highly processed, unhealthy foods, with the aim of maximizing profits.
- Lack of physical activity: Regular physical activity is an important part of obesity prevention and management. Leading a sedentary lifestyle, insufficient daily movement, and inadequate exercise contribute to a high BMI. Globally the world is not meeting minimum physical activity levels.
- Genetics: Genetic predisposition can play a significant role in obesity by influencing metabolism (how the body converts food into energy and fat), appetite and satiety (the feeling of fullness), and where fat is stored in the body. Some rare genetic conditions, such as Prader-Willi syndrome, cause severe obesity.
- Medications: Some medications can contribute to weight gain and obesity, by stimulating appetite (antidepressants, steroids, and antipsychotics); slowing down metabolism which affects how the body stores and absorbs sugar and other nutrients; fluid retention; and body fat redistribution which results in belly fat.
- Hormonal imbalances: Certain hormonal imbalances can contribute to weight gain by affecting metabolism (thyroid hormone), appetite (leptin and ghrelin), and how the body stores fat (cortisol).
- Environmental factors: Urbanization and easy access to junk food, socioeconomic status, poverty and the lack of access to healthy foods, and lack of exercise opportunities in an urban environment can potentially contribute to weight gain.
- Psychological factors: Individuals may turn to food as a coping mechanism for managing stress (chronic stress increases appetite), sadness, or anxiety, which leads to overeating and weight gain. Psychological factors can significantly contribute to weight gain and obesity.
Status of global interventions:
Despite long-standing awareness of the threat to disease and premature death, no country has so far successfully curbed the rising rates of adult overweight and obesity. These conditions are expected to continually rise globally. Prioritizing healthy weight among populations remains a leading global health challenge, as current strategies have failed to address the obesity crisis.
Far more concerted efforts are needed to deliver effective interventions, which are tailored to each country’s unique situation, considering economic, environmental, sociodemographic, and commercial contexts. The ongoing monitoring of the prevalence of overweight and obesity remains crucial, not only for assessing the current status and future trajectory, but also to evaluate the effectiveness of interventions (if any).
Obesity has been on the global health agenda for over two decades, but the implementation of strategic plans into action has been limited and progress has been minimal. The identification and implementation of obesity intervention strategies in real-world settings have been a major challenge.
Conclusions:
If current trends continue without drastic intervention, an estimated 3,8 billion adults older than 25 will be overweight or obese by 2050. This crisis will cause more adverse health outcomes by then than any other modifiable health risk.
Interventions and preventative measures are urgently needed, in particular, in regions such as Asia and sub-Saharan Africa, where a surge in the number of individuals being overweight or obese is expected and where the existing health-care systems are not equipped for the expected rapid escalation of non-communicable diseases.
Obesity should be recognized as a chronic and complex disease that is also a driver of other diseases, increasing the global burden of chronic diseases such as heart disease, diabetes, and cancer. According to the Human Sciences Research Council, almost 50% of adult South Africans are currently overweight or obese.
References:
World Obesity Atlas 2025. Published March 2025 by the World Obesity Federation. London. P.274. (www.worldobesity.org)
Global, regional, and national prevalence of adult overweight and obesity, 1990-2021, with forecasts to 2050: A forecasting study for the Global Burden of Disease Study 2021. Published 8 March 2025 in The Lancet. Volume 405, Issue 10481. (www.thelancet.com)
Let’s put a spotlight on the systems. Published online 2025. World Obesity Day. (www.worldobesityday.org)
HSRC study finds that almost 50% of adult South Africans are overweight or obese. Published 18 March 2024. Human Sciences Research Council. South Africa. (www.hsrc.ac.za)
The perception of overweight and obesity among South African adults: Implications for intervention strategies. Study by the Human Sciences Research Council, South Africa, published 28 September 2022 in International Journal of Environmental Research and Public Health. PubMed Central. National Centre for Biotechnology Information. US National Library for Medicine. National Institutes of Health. USA. (www.ncbi.nlm.nih.gov)
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