Consumers would rather pay more than see their favourite products shrink as brands move to cut costs, a survey suggests.
Brands risk losing up to 35% of their customers if they cut their portion sizes by 15%, a YouGov poll found.
The YouGov Portion Sizes and Health report suggests that 13% of consumers would stop buying a product that had shrunk by 5% and a further 22% would do the same for a product cut by 10%.
The study into food "shrinkflation" - when a brand reduces the size of a product without cutting the price - found that companies risk losing customers as a result of the practice.
According to the YouGov poll, almost half of consumers (46%) would rather pay more than see their favourite products shrink, while 36% would favour the price to stay the same but the portion to decrease.
Although 38% said they still bought a product when they knew it had been reduced in size, almost one in five (19%) stopped buying when the price went up and the size went down and 17% stopped buying because the size went down and the price remained the same.
A number of brands have cut the size of products without alerting consumers while maintaining the price.
Toblerone made headlines late last year when its US producer Mondelez International changed its distinctive mountain peak shape and made bars lighter because of rising ingredient costs.
Stephen Harmston, head of YouGov Reports, said: "The reaction to the news that Toblerone had shrunk the amount of chocolate in its product was met by a mixture of bemusement, confusion and frustration by consumers, but the brand is hardly alone in adopting this approach.
"Our data indicates that these companies are treading a fine line.
"Consumers will only accept a certain degree of downsizing before they look elsewhere, and would rather pay a bit more in order to preserve the portion sizes they have now."
:: YouGov surveyed 1,019 adults online between January 17-23.