Could overeating and driving be as dangerous as drinking and driving? New research says so

  • Today Green Flag research reveals that an astonishing nine in ten (87 per cent) UK drivers are set to experience a festive food lag after eating Christmas dinner
  • Drivers are set to feel sluggish (71 per cent), be unable to control falling asleep (37 per cent) and have slower reaction times (24 per cent)
  • Worryingly, 24 million drivers will drive after they have eaten their Christmas dinner this year - leaving us in danger of accidents due to falling asleep at the wheel
  • Green Flag and leading nutritionist Jenny Tschiesche are urging drivers to take a break after eating, before getting behind the wheel

With Christmas fast approaching and the UK eagerly anticipating their Christmas Day meals, drivers are being urged to take a break after eating before they get behind the wheel over the festive period.

New research released today by breakdown cover provider Green Flag[CJ1], and supported by nutritionist Jenny Tschiesche, has revealed that a staggering 87 per cent of Brits are set to experience a Christmas ‘food coma’ – suffering from adverse effects after eating large, heavy portions over Christmas Day.

Christmas Day Consumption

The average person in the UK will commence the Christmas eating marathon at 9.34 am and won’t wrap up their festive snacking until 6.54 pm. However, over half of Brits (51 per cent) admit they are still eating beyond 9pm on Christmas Day, compared to only a quarter (27 per cent) on a normal day. This means that a large proportion of Brits have a potential eating window of over 12 hours on Christmas Day.

Unsurprisingly, our calorie intake is significantly higher on Christmas Day, with research showing that Brits consume over 60 per cent more calories than normal on Christmas Day, rising from an average of 2,011 calories on a normal day to 3,293 on Christmas Day – meaning as a country we consume an extra 64bn** calories on Christmas Day.

Overeating and Driving

A whopping 53 per cent of drivers – totalling 24 million – will drive after eating on Christmas Day, and Green Flag’s research shows that they are risking slower reaction times and falling asleep at the wheel.

A staggering three quarters (75 per cent) of UK drivers confess to feeling tired after Christmas dinner, while a similar number report feeling sluggish (71 per cent). Over a third (37 per cent) of drivers report that they are unable to control falling asleep and a quarter (24 per cent) of drivers Brits said that they react more slowly to things after their Christmas feast. 

Unsurprisingly, the time we are at our most sleepy on Christmas Day is in the afternoon – and most of us will feel our worst at 4:43pm.

While motorists are conscious of the need to avoid alcohol altogether when planning to drive at Christmas (66 per cent), drivers are far less informed when it comes to the effect that eating can have on reaction times. In fact, only 24 per cent of UK drivers are inclined to eat smaller portions of Christmas dinner if taking to the road.

Jenny Tschiesche, Nutritionist and BSc (Hons) Dip(ION) FdSc BANT, said:  “People reporting desperate tiredness after their Christmas dinner isn't surprising considering the amount of carbohydrates we'll consume on Christmas Day. Similarly, the sluggishness people experience is caused because there's a high salt content in our festive treats, and this makes our bodies retain water.

“What is surprising however is the danger drivers are putting themselves in. People must take care after consuming stodgy foods this Christmas, and there are some simple safety measures you can take on Christmas Day if you find yourself needing to drive. Just making sure you have enough water throughout the day will keep you hydrated and banish the sluggishness. Favouring non-starchy vegetables on your dinner plate is also going to help keep your energy levels up, in other words, eat your sprouts! Also think about the run up to Christmas. Make sure you get enough sleep before the big day, and don't crash diet to prepare for a big meal.

“The most dangerous time to drive is three hours after eating. That's because most of us have a metabolic rate of about three hours, so this is the point where we will feel the most tired. The optimum time to wait after your Christmas dinner before driving is about five hours, when our bodies have digested the majority of the festive food."

Drivers’ Views

Although the vast majority of drivers reported symptoms of tiredness, slow reactions, sluggishness and not feeling alert after eating heavily, shockingly, less than a fifth (17 per cent) of drivers think that it’s dangerous to drive when experiencing a ‘food coma’ and less than a quarter (22 per cent) would rather walk than drive when experiencing these symptoms.

Extra Weight in Cars 

With presents being ferried from home to home, drivers should also be aware of the extra weight they’ll be carrying in their cars this Christmas. According to the research, vehicles will weigh an additional 13 kilos on average when factoring in the Christmas presents being carried. As a result, as a nation we’ll spend an additional £945,000*** on fuel. [CJ2]

Candace Gerlach, head of marketing at Green Flag, commented: “As families and friends gather to celebrate the Christmas festivities, undoubtedly, food will be a central feature of the merriments. While drivers are well-informed of the dangers & effects of driving after consuming alcohol, this isn’t the case when it comes to over-eating.

“Our research shows that a massive nine in ten Brits experience a festive food lag after Christmas dinner, however, just a fraction of Brits are aware of the effects that this can have on driving, with over half of motorists willing to drive almost immediately afterwards.

“While food is a wonderful part of Christmas, we’re urging Brits to be conscious of their consumption and how it impacts their bodies. Drivers should have a break from eating, and let their food digest properly, before getting behind the wheel.  The most important thing is that people have the most brilliant time over the Christmas period with friends and family. And remember Green Flag are 24/7. So if you do breakdown, one of our technicians will come and rescue you from your food coma no matter what time it is!”

 Green Flag’s Common-Sense Tips For Driving Over Christmas:

  • Ensure you get enough sleep in the run-up to Christmas Day
  • Drink water throughout the day to keep hydrated and banish sluggishness
  • Eat non-starchy vegetables during dinner to help keep your energy levels up
  • Avoid driving wherever possible when you feel sluggish or sleepy
  • If you need to drive, wait five hours after your Christmas dinner before driving
  • Share driving on long journeys wherever possible
  • Don't drive unaccompanied after your Christmas meal
  • If you're feeling tired, pull over
Symptom drivers experienced in a ‘food coma’ 



75.2 per cent


71.1 per cent

Inability to control falling asleep

37.1 per cent

Reacting more slowly to things

24.1 per cent

Inability to concentrate

14.2 per cent


13.6 per cent


10.9 per cent

What drivers do to get over a ‘food coma’


Watch TV

42.6 per cent

Go for a walk

38 per cent

Succumb to it & fall asleep

36.4 per cent

Drink coffee after Christmas dinner

15.9 per cent

Start an argument to feel energised

1.6 per cent

- ENDS -



Notes to Editors: 


*Research carried out by Censuswide on 2,000 British drivers, November 2018,


** based on UK adult population (20+), ONS


***based on 31.5 million cars on Britain’s roads. Based on weight of a Ford Focus. Additional 3p per driver spent. 


About Green Flag 


With over 40 years' experience, Green Flag provides customers with breakdown cover 24 hours a day, 365 days a year. Customers have access to a network of breakdown operators across the UK and mainland Europe (Euro Plus cover required).


Green Flag Motoring Assistance is underwritten by U K Insurance Limited, Registered office: The Wharf, Neville Street, Leeds LS1 4AZ. Registered in England and Wales No 1179980. U K Insurance Limited is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority.


Green Flag and U K Insurance Limited are both part of Direct Line Insurance Group plc. 


Customers can find out more about Green Flag products or get a quote by calling 0345 246 1557, connecting via the Green Flag Rescue Me Application, or visiting