Approximately two-thirds of UK adults are overweight or living with obesity, increasing the risk of conditions such as heart disease, stroke and Type 2 diabetes. New research suggests lower working hours could be linked to a decrease in obesity rates – leading to renewed calls for a four-day work week.
But why might working less lead to weight loss? Surely keeping people busy at their jobs is an effective encouragement to eat less, move more and achieve a calorie deficit?
Not so, according to the research presented at the European Congress on Obesity in Istanbul. Authors found that a 1 per cent reduction in annual working hours was associated with a 0.16 per cent reduction in obesity rates in the countries studied.
One explanation is that jobs are becoming more sedentary and energy-dense foods are often at hand when we’re in the office. Another potential mechanism playing into these findings is stress, and cortisol – sometimes called the “stress hormone” – in particular.
But how much does this impact our weight and can it be controlled?
What is cortisol and how does it impact weight loss?
Cortisol is the body’s primary stress hormone. It is produced by the adrenal glands and affects several areas of your brain to impact stress, mood, motivation and fear. It also plugs into a number of important bodily processes, such as inflammation levels, blood pressure regulation and sleep patterns.
It is helpful and necessary in many cases. But recently it has developed an unfavourable reputation.
Certain social media users have propagated phrases such as “cortisol belly” and “cortisol face” – triggered by the idea that high-stress lifestyles and sub-optimal routines can spike cortisol levels, driving weight gain, inflammation and puffiness in the face.
But for the vast majority of people, these trending terms aren’t worth stressing over, according to experts. “Yes, it’s true that stress (whether caused by an approaching sabre-toothed tiger or having a high-pressure job) rapidly and reliably triggers cortisol release,” Craig Doig, an associate professor of metabolic health at Nottingham Trent University, writes in The Conversation. “But this isn’t bad. Cortisol isn’t trying to ruin your summer body, it’s trying to keep you alive and give you the energy to run or fight.”
Research has previously shown that people with chronically high cortisol levels are more likely to store fat around the stomach and face, Doig adds. “But this applies to Cushing’s syndrome, a rare medical disorder. The cortisol released from everyday stress doesn’t even come close to the levels or duration seen in Cushing’s.”
If you are experiencing symptoms of Cushing’s syndrome – described on the NHS website – you should speak to a qualified healthcare professional.
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The relationship between stress and weight gain
Excessive stress is not good for your health, and there is a relationship between cortisol and weight management. Research suggests this is driven more by the behaviours that come with higher stress levels, rather than the extra cortisol release in and of itself.
For example, stress might lead us to eat more and seek out “comfort food”. A Harvard Medical School article reports that elevated cortisol levels can increase appetite and may steer us in the direction of foods high in fat and sugar.
A narrative review published in the International Journal of Preventive Medicine states: “Stress is definitely not the only factor involved in obesity – many genetic and environmental causes contribute to it, but it is one of the biggest reasons contributing towards it.
“… Researchers have revealed that people eat more in stress compared to when they are happy because of the release of a hormone by our body called cortisol. However, stress-induced eating can be hard to eliminate because eating is pleasurable.”
For decades, governments have encouraged people to move more and eat less to curb rising obesity rates, but current numbers suggest this approach isn’t working. Authors of the research on working hours and obesity rates say it could instead be beneficial to consider people’s lifestyle, gender and psychological state, identify the root cause of obesity, and then make suitable interventions from there.
The standardised advice for lowering stress and cortisol levels is remarkably similar to the advice given for leading a healthy life in general: sleep well, eat a nutrient-dense diet, exercise regularly and enjoy time with friends.
If you can adhere to these four pillars, many more health perks await. Stress management techniques such as breathwork, meditation and journalling may also help.
Read more: The science behind a good night’s sleep
Other factors that could explain the link between working hours and weight gain
The demonisation of cortisol is emblematic of a wider problem in the health and fitness world: people are on the hunt for quick fixes and simple solutions to every problem. The issue with weight loss is that it is far from straightforward and there are myriad factors at play.
Calorie balance – whether you burn more energy or consume more energy – will be the ultimate determinant of any changes to your weight, but there is a long list of variables that play into this. For example, genetics (roughly 20 per cent), appetite, income, environment, sleep routine, exercise opportunity, food availability and alcohol intake.
The new research suggests that higher working times could have a negative impact on several of these factors, leaving people with less time for exercise, increased stress levels and a greater reliance on energy-dense convenience foods. Those working longer hours may involve doing shift work, disrupting the circadian rhythm – a 24-hour internal clock which contributes to the smooth running of nigh-on every system in the body.
“These results underscore the need for coordinated policy responses that extend beyond individual behaviour change,” the study’s authors say. “Addressing obesity effectively requires an integrated approach that considers labour market dynamics, urban design and food system governance.
“Policy interventions aimed at improving work-life balance, promoting active transportation and fostering healthier food environments may play a critical role in mitigating obesity risk.”
“A four-day week on full pay could slash Britain’s obesity levels by giving millions the time they need to ditch bad habits and make healthier choices,” adds James Reeves, a campaign manager at the 4 Day Week Foundation.
“It’s essential that local and national governments seriously consider the role that a shorter working week can play in improving the health of our communities. The nine-to-five, five-day working week is 100 years old and we’re long overdue an update.”
“Full pay” is an important phrase to highlight here, with several studies connecting lower incomes with a higher risk of obesity. In 2023, a UK government report stated that one in five UK households were struggling to access “good quality food at reasonable prices,” often forcing people towards “unhealthy, high-calorie alternatives”.
Walk down most UK high streets, take note of the food options available and the ones that are most affordable, and this issue is laid bare. Fast food outlets selling energy-dense foods with little nutritional value are prevalent.
A four-day work week would increase opportunities to exercise, cook from scratch and pre-prepare more nutritious meals for the days ahead, supporters argue. People could complete tasks often filed under the “life admin” umbrella on their extra day off, freeing up more time through the rest of the week.
In answer to calls for a four-day work week, a government spokesperson said: “This government will not mandate a four-day work week for five days’ pay. But through the Employment Rights Act, we’re making it easier for flexible working requests to be accepted.”
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