Shoppers whose supermarket trolleys are stacked with food and drink offered on special promotions have more than a 50% increased chance of being obese, according to a Cancer Research UK report published today.

This puts them at a greater risk of 13 different types of cancer including bowel and breast.

In Scotland, a quarter of children start school overweight or obese. And among adults, excess weight is Scotland’s biggest preventable cause of cancer after smoking. Around 2,200 cases of cancer a year in Scotland – around six a day – are down to being overweight or obese.

To turn the tide and deter shoppers from stocking up on junk food, Cancer Research UK is urging the Scottish Government to introduce laws to restrict multi-buy offers on unhealthy food and drink.

The study, which looked at the habits of more than 16,000 British households, found that people whose shopping baskets contained around 40-80% of goods on special offer have a greater chance of piling on the pounds. The research also found that almost half of all chocolate, crisps, popcorn, and savoury snacks were bought on promotion.

Multi-buy shoppers also bought 30% less fruit, and nearly 25% fewer vegetables. This equates to nearly 6kg less of fruit and veg every month than shoppers more inclined to shun the special offers.

Around 3 in 10 food and drink products in shoppers’ baskets are bought on promotion in Great Britain, according to the findings. And the people who purchased the most items on offer bought 25% more food and drink high in fat, salt or sugar, equating to approximately 11 extra unhealthy items a month.

Obesity was almost 30% higher among people from households which bought the most food and drink on special promotions compared to those who bought the least.

Two thirds of the public in Scotland back moves to restrict price promotions on foods that are high in fat, sugar and salt.

Professor Linda Bauld, Cancer Research UK’s prevention expert, who is based at the University of Edinburgh, said: “Promotional items offer people a wealth of tempting yet unhealthy food and drink choices when doing their weekly shop. With cut-price deals on things like chocolate, biscuits, cakes and fizzy drinks, it’s no surprise that people who buy more on promotion have a greater likelihood of being obese.

Photo: Professor Linda Bauld, Cancer Research UK’s prevention expert, who is based at the University of Edinburgh

“With young children frequently being the ones who suffer from the effects of these purchases, introducing restrictions is important for their future health.

“With an obese child five times more likely to become an obese adult, it’s vital swift action is taken to turn the tide.

“By introducing laws to restrict multi-buy offers on junk food and sugary drinks, the Scottish Government can make a real difference to our shopping baskets and to our waistlines.”