1. Key messages
- Overweight and obesity are one of the most significant risk factors of the twenty-first century related to an increased risk of the occurrence of non-communicable diseases and associated increased healthcare costs.
- In Belgium, it is likely that the prevalence of obesity will have further increased by 2030 among men and women. For overweight, an increase in the prevalence among women and a steady state among men seems the most likely scenario.
- The current projections show that the WHO target to halt obesity by 2025 will most likely not be achieved in Belgium.
2. Past, present, and future trends of overweight and obesity in Belgium
Overweight and obesity are known to be important risk factors for a wide range of negative health outcomes, such as cardiovascular diseases, type 2 diabetes, colorectal, prostate, and renal cancer, and many other non-communicable diseases. As the number of people that suffer from overweight or obesity has been rising in the past decade, a global target to halt obesity at 2010 levels by 2025 was adopted during the World Health Assembly in 2013 , whereby consensus was reached to prevent further growth in the number of men and women with obesity above the observed prevalence in 2010.
As obesity has been recognized as a major public health problem in Europe, research on its likely evolution in European countries is necessary. To this end, a variety
of statistical models have been applied to the European context, such as linear extrapolations and non-linear functions. The diversity in methodologies employed differed substantially, and not all were able to yield realistic obesity or overweight estimates for the near future. To better comprehend the complexity underlying the overweight and obesity epidemic, and obtain reliable and valid projections, it is important to consider the contributing risk factors, such as age, sex, and education, but also lifestyle habits such as sedentary lifestyles and the consumption of high-calorie foods. One of the popular methods to estimate future projections based on previous trends is age-period-cohort (APC) analysis. APC analysis includes an age effect, which reflects the association between age and weight status, a period effect, which reflects the evolution of weight over time, and a birth cohort effect, which reflects the degree to which an individual’s weight is receptive to societal and social changes.
In Belgium, trends in overweight and obesity are captured through the different waves in the Health Interview Survey (HIS) . The Belgian HIS contains a series of repeated cross-sectional surveys that were conducted during six national waves in 1997, 2001, 2004, 2008, 2013, and 2018. The goal was to collect information on the health status, determinants, and health behaviors of approximately 10,000 individuals in each survey round. General information on overweight and obesity can be found on a dedicated page. To estimate the likely projections of overweight and obesity in Belgium for the years 2025 and 2030, we have applied an APC analysis building on the different waves from the Belgian HIS in men and women .
In 2030, 1 in 2 men and women will suffer from overweight in Belgium
In Belgium, a steady state to a slight decrease was estimated in men from 54,764 [54,764; 55,125] per 100,000 in 2018 towards a projected 53,616 [36,291; 70,866] cases per 100,000 in 2025, and 52,273 [21,216; 83,249] cases per 100,000 in 2030. In women, the projections showed a strong increase in cases from 44,070 [43,884; 44,255] per 100,000 in 2018 towards a projected 46,147 [19,666; 74,114] per 100,000 in 2025, and 49,147 [7275; 90,899] per 100,000 in 2030. In contrast, a high increase was observed for obesity in men from 17,453 [17,322; 17,585] cases per 100,000 in 2018 to 22,497 [13,622; 35,616] cases per 100,000 in 2025, and 27,566 [9938; 57,358] cases per 100,000 in 2030. In women, the rate of increase was almost as high compared to men with cases increasing from 15,246 [15,125; 15,369] cases per 100,000 in 2018 to 15,954 [6354; 35,020] cases per 100,000 in 2025, and 17,186 [2552; 61,803] cases per 100,000 in 2030.
- Overweight projection
- Obesity projection
Unadjusted prevalence of overweight per 100.000 by sex, Belgium, 1997-2030.
Source: De Pauw et al. 
Unadjusted prevalence of obesity per 100.000 by sex, Belgium, 1997-2030.
Source: De Pauw et al. 
In 2030, the number of people being overweight will more likely increase than decrease
In addition to the projected prevalence, the probability to see an increase in the future compared to the prevalence estimates for overweight and obesity for the year 2018 was estimated. In men, there is a 43.3% chance for an increase in the number of people with overweight by the years 2025 and 2030. The chance for an increase in the number of men with obesity by the years 2025 and 2030 is much higher in comparison, with estimated probabilities of 86.7% and 84.1%, respectively. While in women, there is a 56.0% and 57.4% probability for an increase in the rate of overweight by the years 2025 and 2030, respectively. The probability of an increase in the number of women with obesity by the years 2025 and 2030 is 54.6% and 56.0%, respectively.
Probability of increase in rate by >0, >5, >10, >25, >50 and>100% based on the future APC projections compared to the 2018 prevalence estimates.
Source: De Pauw et al. 
|Increase > 0%||43.3%||43.3%||56.0%||57.4%||86.7%||84.1%||54.6%||56.0%|
|Increase > 5%||30.4%||36.6%||49.6%||54.2%||81.9%||81.6%||49.6%||53.5%|
|Increase > 10%||19.9%||30.4%||43.2%||50.9%||76.2%||78.9%||44.8%||51.2%|
|Increase > 25%||4.0%||15.3%||25.7%||41.0%||55.6%||70.1%||32.0%||44.5%|
|Increase > 50%||0.1%||2.8%||7.6%||25.2%||24.4%||54.7%||17.3%||35.1%|
|Increase > 100%||<0.1%||<0.1%||0.1%||3.8%||2.9%||28.3%||4.9%||21.4%|
3. Read more
- Overweight was defined based on the body mass index (BMI), which was calculated using the information on self-reported height and weight, and categorized as overweight if the BMI ≥ 25kg/m2.
- Obesity was defined based on the body mass index (BMI), which was calculated using the information on self-reported height and weight, and categorized as obesity if the BMI ≥ 30kg/m2.
- World Health Organization (WHO). European health report 2015: targets and beyond-reaching new frontiers in evidence. 2015. https://apps.who.int/iris/handle/10665/327873
- Belgian Health Interview Survey (BHIS), Sciensano, 1997-2018. https://www.sciensano.be/en/projects/health-interview-survey
- De Pauw, R., Claessens, M., Gorasso, V. et al. Past, present, and future trends of overweight and obesity in Belgium using Bayesian age-period-cohort models. BMC Public Health 22, 2022. https://doi.org/10.1186/s12889-022-13685-w