Shoppers who buy food and drink offered on special promotions are 50% more likely to be obese, according to a Cancer Research UK study.
Almost half of all chocolate, crisps, popcorn and savoury snacks were bought on promotion, the study for Cancer Research UK of more than 16,000 British households found.
People whose shopping baskets contained between 40% and 80% of goods on special offer have a greater chance of piling on the pounds and are therefore at a higher risk of cancer, the charity warned.
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.
Multi-buy shoppers also bought 30% less fruit and nearly 25% fewer vegetables – nearly 6kg less of fruit and veg every month than shoppers more inclined to shun the special offers.
Being overweight is Scotland’s biggest preventable cause of cancer after smoking, with about 2,200 cases of cancer a year in Scotland – roughly six a day – are down to being overweight or obese.
Cancer Research UK is now urging the Scottish Government to introduce laws to restrict multi-buy offers on unhealthy food and drink, a policy they claim is supported by two-thirds of Scots.
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.
“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.”
Public Health Minister Joe FitzPatrick said: “We want to reduce the public health harm associated with poor diet and the excessive consumption of food and drink high in fat, sugar or salt.
“We know that multi-buy promotions in particular can encourage people to buy more than they need in order to obtain a discount. That is why the Scottish Government recently consulted on restricting the in-store promotion and marketing of foods with little nutritional value, including multi-buys.
“We are currently considering all responses to our consultation which will help us consider our next steps.”