News release

From: International Congress on Obesity (ICO2026)

The effect of obesity on unemployment more than twice as large as previously thought, finds UK Biobank study of genetic evidence

· Study of over 280,000 adults finds 4 out of every 100 people living with obesity likely to be unemployed solely due to obesity, independent of age, education, and deprivation.

· Obesity appears to have a stronger effect on employment in men than women

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New research being presented at this year’s International Congress on Obesity (ICO2026) hosted by the World Obesity Federation (WOF) in Mexico City, Mexico (15-17 July) supports a strong causal link between obesity and unemployment, underscoring the need for targeted initiatives to help people living with obesity enter and remain in employment.

By analysing genetic variants robustly associated with increased body mass index (BMI) in over 280,000 individuals, researchers found that obesity's true causal impact on employment is more than twice as great as conventional methods suggest, with a 4.2 percentage point reduction in the likelihood of being in paid work, compared with 1.8 percentage points using traditional statistical approaches.

These findings suggests that out of every 100 people living with obesity, around 4 fewer are likely to be in paid employment solely due to obesity than would otherwise be expected—a gap not explained by other factors such as age, education, or deprivation, since the genetic method rules those out.

Previous traditional epidemiological studies have found that obesity is linked with higher unemployment, greater sickness absence, and lower wages, costing the UK an estimated £31 billion a year in lost productivity alone, with a total annual economic and societal cost of around £126 billion [1]. People with obesity often face discrimination in the workplace, which may contribute to these associations.

But observational studies have struggled to establish causal links due to confounding (i.e., common underlying causes of both weight and employment outcomes, such as low education) and reverse causation (i.e., being unemployed might also increase the chance of having a higher BMI through stress, loss of income, or lower physical activity).

To isolate the effects of BMI on paid employment, researchers used a technique called Mendelian randomisation, which uses a person's genetic predisposition to higher BMI. This is fixed randomly at birth and a stand-in for their actual body weight. Because genetics aren't influenced by someone's job, income or lifestyle, this approach strips out the usual confounding factors and reveals obesity's true causal effect on employment, rather than just a correlation.

Researchers drew on data from 284,258 volunteers (130,387 female and 153,871 male) of working age (men 38–65 years, women 38–60 years), with suitable genetic and employment data from the UK Biobank. To address the potential limitations of BMI in the diagnosis of obesity, they also used alternative measures (waist-to-height ratio and waist-to-hip ratio) to assess the robustness of the results.

Overall, the average employment rate was 75.5% and around one in four participants were living with obesity (BMI ˃30 kg/m²). Participants with obesity tended to have lower employment rates (72.3% vs 76.5%) and were less likely to have a degree (26.3% vs 37.8%) than those without obesity (BMI 18.5–29.9 kg/m²). They were also slightly older on average (53.3 vs 52.7 years) and more socioeconomically deprived.

Traditional prediction analyses (which are more subject to bias) found that among people of working age, obesity was associated with a 1.8 percentage point reduction in the likelihood of being in work, after controlling for a variety of factors including sex, education level, geographical deprivation score, and age.

However, this became greatly increased in Mendelian randomisation analyses that better controlled for confounding factors and reverse causation, which found that obesity was associated with a 4.2 percentage point reduction in the likelihood of being in paid employment compared to those without obesity.

The weight of discrimination

The findings also point to an age dimension. The employment penalty associated with obesity appears to grow more sharply with age for women than for men, although the overall effect across all working-age women is smaller than for men, possibly because women in the sample skew younger. The researchers say further work is needed to pin down exactly which age groups are most affected.

However, in further analyses accounting for hidden factors (e.g., individual preferences, job satisfaction, motivation) behind the existence of employment penalties due to obesity, the story is quite different. Men living with obesity face a more pronounced penalty. Using the more advanced statistical approach, the researchers found that obesity was associated with a much smaller reduction in employment among women, but a substantially larger reduction among men. For women, the estimated reduction in employment fell from 4.7% to 2.1%, while for men it increased from 3.9% to 6.6%.

According to lead author Dr Aharon Katz from the University of York, UK, “These contrasting findings point to different labour-market consequences of obesity for men and women. The differences may reflect variations in occupational sorting, health-related work limitations, employer discrimination, or broader social roles that influence employment decisions differently by gender. At this stage, however, these mechanisms remain speculative, and further research is needed to determine why obesity appears to have a stronger employment effect among men than women.”

The researchers also found that individuals with obesity and lower levels of education (i.e., without a degree) were significantly more likely to be out of work. Interestingly, having a degree also appeared to have a protective effect on employment, suggesting that the negative effects of obesity on employment are exacerbated among socioeconomically disadvantaged communities.

“Our findings provide strong evidence of a substantial causal effect of obesity on the likelihood of being unemployed across all estimation methods and measures of obesity,” said Dr Katz. “Tackling obesity isn’t just a health imperative, it’s an opportunity to boost economic productivity. Because obesity affects workers in the prime years of their working lives, it may have profound effects on their working careers, individual health and societal costs.”

He adds, “These findings call for a targeted and nuanced approach to tackling the negative effects of obesity on employment and to mitigate the substantial economic losses of soaring obesity rates. Policy interventions and workplace initiatives should aim to raise awareness, challenge biases, and promote inclusivity.”

The researchers note some limitations of their study, including that the study is not randomly representative of the UK population, with the authors noting a well-known selection bias in UK Biobank participants who tend to be healthier, wealthier and better educated than the general population. Moreover, the study sample was restricted to White UK subjects as different racial and ethnic populations require distinct combinations of genetic variations to accurately determine genetic risk, so the results may not generalise well to other UK ethnicities. The authors say that future research should examine the effects in other ethnic groups and compare effects across populations and societies with different labour markets.