Does "Overworking" Lead to Weight Gain?—The Day a Four-Day Workweek Becomes a Health Policy

Does Long Working Hours Lead to Obesity?—Why the "Four-Day Workweek" is Being Discussed as a Health Policy

When people hear "causes of gaining weight," many might first think of overeating or lack of exercise. Of course, the basic principle of weight gain involves the balance between energy intake and energy expenditure. However, in recent years, attention has also been focused on factors such as living environment, work style, stress, and lack of sleep.

A new international study reported by the British newspaper Mirror re-examines the relationship between "working hours" and "obesity rates" from precisely this perspective. The study, which is set to be presented at the European Congress on Obesity in Istanbul, Turkey, analyzed data from 33 OECD countries from 1990 to 2022. It found a tendency for countries with longer annual working hours to have higher obesity rates, and a 1% reduction in annual working hours was associated with a 0.16% decrease in obesity rates.

At first glance, these numbers might seem small. However, when converted to the national obesity rate, the impact is significant. The Mirror article also introduces an estimate that if a four-day workweek, which reduces working hours by 20%, were to spread, the number of people classified as obese in the UK could decrease by about 500,000.

However, it is important to note that this study does not prove that "working long hours will inevitably make you gain weight." The researchers themselves caution that the results indicate a correlation, not causation. Factors such as income levels, food culture, urban environment, healthcare systems, commuting time, and household and childcare burdens all affect obesity rates. It cannot be explained solely by working hours.

Nonetheless, the study is gaining significant attention because many people feel on a daily basis that "being too busy prevents them from living healthily."

Chased by work from morning till night. Exhausted upon returning home. No energy to stop by the supermarket or to cook. Even if you want to exercise, it's already late at night. Weekends are spent catching up on household chores and recovering from lack of sleep. In such a lifestyle, relying on convenient processed foods, delivery, snacks, and alcohol is not merely a sign of weak willpower. It can be said that a time-poor lifestyle narrows people's choices.

This concept of "time poverty" is central to the current discussion. Just as economic hardship is called poverty, a lack of time to live healthily is also a serious issue that affects the quality of life. Choosing ingredients, cooking, exercising, sleeping adequately, and relieving stress—all these are easier to execute when time is available.

Researchers mention not only the lack of exercise time but also the impact of workplace stress as potential links between long working hours and obesity. When stressed, hormones like cortisol are secreted in the body. This mechanism is originally meant to prepare the body for action in the face of danger, but modern stress often occurs while sitting at a desk. The body is ready to use energy, but it is not actually consumed. If this state continues, it can adversely affect appetite, sleep, and fat accumulation.

Moreover, sleep disturbances are significant. Working late, continuously checking smartphones and emails, and going to sleep with an unrested mind. If sleep time is shortened or sleep quality deteriorates, it affects appetite and concentration the next day. When tired, the body tends to crave quick energy sources. Reaching for sweets or fatty foods is not just a preference but also a response of a fatigued body and brain.

Against this backdrop, the article highlights the "four-day workweek" as a potential solution. In the UK, a large-scale pilot experiment has already been conducted, and in the 2022 trial involving 61 companies and about 2,900 people, many companies reported maintaining productivity even after reducing working hours, with improvements in employee stress and burnout. The fact that many participating companies continued the four-day workweek after the trial has become widely known as a symbolic example of work style reform.

Supporters of the four-day workweek argue that it is not merely a "system to increase holidays," but a system to review how work is conducted. Reducing unnecessary meetings, securing focused time, and clarifying work priorities. The resulting free time is allocated to employees' sleep, exercise, family time, meal preparation, medical visits, learning, and community activities. The idea is that if health and work motivation improve as a result, it benefits both companies and society.

However, reactions on social media are not unanimous.

On public forums like Reddit, voices agreeing with the report's findings are prominent. Opinions include that there is no energy left for cooking or exercising after long hours of work, that free time is surprisingly limited when commuting and household chores are included, and that time, rather than willpower, is needed for a healthy lifestyle. Particularly from households with children and people with long commutes, there are reactions that the assumption of making a healthy dinner and exercising after work is unrealistic.

Additionally, many express that "with a five-day workweek, weekends end with recovery and chores." Shopping, cleaning, laundry, errands at government offices or hospitals, family plans. Just handling these consumes Saturday and Sunday, and by Monday, they return to work still tired. There is hope that with a three-day weekend, one day could be used to reorganize life, and the remaining time could be devoted to real rest and exercise.

On the other hand, there are also many skeptical reactions. A common point is the critique that "comparing average working hours and obesity rates by country alone does not reveal the cause." For example, factors related to obesity include food culture, income disparity, urban design, food prices, whether a society is car-dependent, education levels, and access to healthcare. There are examples of countries with short working hours but high obesity rates, and conversely, countries with long working hours but low obesity rates. On social media, there are opinions warning that this research might be conveniently used to promote the four-day workweek.

Furthermore, there is the issue of whether the four-day workweek can be equally introduced to all professions. It might be relatively easy to implement in office jobs or IT companies. However, in workplaces that require manpower and on-site response, such as healthcare, caregiving, logistics, food service, retail, education, and manufacturing, it is not simple. If working hours are reduced, more staff would be needed, and the discussion of who bears that cost is unavoidable.

There is also concern that if a "four-day workweek" simply means cramming five days' worth of work into four, it could be counterproductive. If it results in working 10-hour days for four days, weekday fatigue might actually increase. To expect health benefits, the design needs to reduce total working hours, not just compress workdays.

This point is also an important issue for Japan. In Japan, correcting long working hours has been a long-standing challenge, and the term "karoshi" (death from overwork) is known overseas. On the other hand, in recent years, work style reforms, remote work, side jobs, and flextime have spread, and awareness of managing working hours is changing. However, in reality, the gap is widening between those who can leave work on time and those who become busier due to labor shortages.

If considering the four-day workweek as a health policy, it is not enough to introduce it merely as a welfare benefit for progressive companies. It must be a system that benefits low-income groups, non-regular workers, on-site workers, and those involved in care work; otherwise, it could widen health disparities. If those who get more time off become healthier while those who cannot take time off become busier, the system would deviate from its original purpose.

When it comes to obesity measures, messages often target individuals with "eat less," "exercise," and "self-manage." However, what this study suggests is the necessity of reviewing the time design of society itself, not just individual efforts. For people to make healthy choices, an environment that allows those choices is necessary. Time to cook, time to walk, time to sleep, time away from stress. These are the foundations of health and cannot be considered separately from work styles.

Of course, the four-day workweek is not a panacea. Obesity is a complex issue involving diet, exercise, sleep, genetics, medication, psychological state, and social environment. It is not something that can be solved merely by reducing working hours. However, if long working hours are hindering a healthy lifestyle, it is also unrealistic to demand only individual efforts while leaving that unaddressed.

This study could serve as an opportunity to reconsider obesity not only as a "lifestyle disease of individuals" but also as an "issue of societal time allocation." The divided opinions on social media reflect how many people feel the relationship between work styles and health is a personal concern.

The discussion around the four-day workweek is not just about a labor system. It is also a debate about how society ensures time for healthy eating, moving, and sleeping. It involves discussions about future public health, corporate management, family life, and the humane use of time.

Source URL

Report by Mirror on the relationship between long working hours and obesity rates, and the discussion around the four-day workweek. See uploaded text for more details.
https://www.mirror.co.uk/news/health/people-who-work-longer-more-37130521

Guardian: Summary of the same study, analysis of 33 OECD countries, correlation between a 1% reduction in working hours and a 0.16% decrease in obesity rates, supplementary report on the four-day workweek.
https://www.theguardian.com/society/2026/may/10/experts-call-for-uk-four-day-week-as-study-links-long-work-hours-to-obesity

European Congress on Obesity 2026: Official information on the European Congress on Obesity where the study will be presented.
https://eco2026.org/

OECD "Hours worked": Definitions and data on annual actual working hours by country.
https://www.oecd.org/en/data/indicators/hours-worked.html

OECD "Overweight or obese population": Definitions and data on overweight and obese populations.
https://www.oecd.org/en/data/indicators/overweight-or-obese-population.html

OECD "Obesity, diet and physical activity": Overview of obesity, diet, and physical activity in OECD member countries.
https://www.oecd.org/en/topics/obesity-diet-and-physical-activity.html

NHS "Get help with stress": Public information on stress symptoms, impact on sleep and eating behavior, and coping methods.
https://www.nhs.uk/mental-health/feelings-symptoms-behaviours/feelings-and-symptoms/stress/

WHO "Obesity and overweight": Basic information on the causes of obesity, health risks, and environmental and psychosocial factors.
https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight

Autonomy "The results are in: the UK’s four-day week pilot": Report on the large-scale trial of the four-day workweek in the UK, involving 61 companies and about 2,900 participants.
https://autonomy.work/portfolio/uk4dwpilotresults/

4 Day Week Global "The 4 Day Week UK Results": Data on outcome indicators, burnout, and turnover rates from the UK four-day workweek trial.
https://www.4dayweek.com/uk-pilot-results

Reddit r/unitedkingdom: Examples of reactions on social media and forums regarding the Guardian report. Discussions on skepticism about research methods and empathy for time scarcity.
https://www.reddit.com/r/unitedkingdom/comments/1t9ny8k/experts_call_for_uk_fourday_week_as_study_links/

Reddit r/unitedkingdom: General user discussions on obesity measures, free time, meal preparation, and work and household burdens.
https://www.reddit.com/r/unitedkingdom/comments/1m29zc8/how_can_the_government_tackle_the_obesity/

Reddit r/productivity: Discussions on the 40-hour workweek, lack of time for commuting, chores, and exercise, and impacts on health.
https://www.reddit.com/r/productivity/comments/1hqlzvn/40_hours_of_work_every_week_for_decades_is_simply/