Millennials are leading a revolution in snacking, with 86% of them eating between mealtimes during the working day, as opposed to 60% of baby boomers.
The findings came as part of new research from foodservice firm Compass Group UK and Ireland, carried out by Kantar TNS.
Compass said the changes in behaviour among the younger generation showed how generational purchasing were shifting, with the decreasing length of the lunch break contributing to the significant growth in the "grab and go" market, now worth £20.1b.
Millennials, also known as Generation Y, are typically defined as those being born from 1980 onwards with birth years ending in the mid-1990s to early 2000s. Baby boomers were born in the post-war years from the 1940s until the mid-1960s.
The survey found that the British lunch break is continuing to shrink, with workers now taking an average of 34 minutes for lunch against the European average of 37 minutes.
The UK has seen a 29% increase in lunch spend during the working day since 2012, with consumers now spending an average of £3.03 each day, which makes up 78% of the overall working day spend on food and drink.
A large majority of UK workers (63%) still favour a sandwich for lunch, with 28% having hot sandwiches or wraps.
Currently 52% of office-based workers eat alone at their desks, although 45% of millennials say they wish to meet their colleagues more often over lunch, compared with 23% of baby boomers.
When looking at the main drivers behind people's lunch purchasing decisions, it is taste (46%), price (43%), value for money (42%) and healthy options (23%) that lead the way.
Louise Pilkington, marketing director at Compass Group UK and Ireland, said: "The grab-and-go market is showing no signs of slowing, having reached a staggering £20.1b and continuing to grow over at over 5% a year. This reflects our research findings that more and more people are seeking portable food to fit in with their working day, as workers feel more time-limited over the lunch time break. This trend only looks set to continue as the millennials spend more on and grab-and-go food than any other generation.
"However, we feel employers should be aware of the risks of employees eating at their desks and help them to reclaim their lunch break. With over 50% of workers still eating at their desks, our research shows that employees feel this significantly impacts upon productivity. Ultimately, employees are more productive when they have opportunities to eat together, interact, think and recharge. Lunch is a really valuable part of the day, both to encourage greater motivation and engagement. Therefore, employers should do more to encourage better lunchtime eating habits through the provision of break-out space and facilitating a more collaborative culture over lunchtime.
"Additionally, another simple fix that would boost creativity and also overcome the common issue of limited meeting space is, where it exists, better utilising the workplace food offer area. More can be done to encourage employees to use his space outside the core lunchtime hours, further encouraging collaboration and engagement."
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