Greggs will move its self-serve food and drinks to behind the counter to stamp out shoplifting at the High Street bakery.
The company is trialling the measure at a handful of stores which, it said, are "exposed to higher levels of anti-social behaviour".
These include Whitechapel in east London which is one of five shops that will try out the new policy - the others are in Peckham and Ilford.
It is not expected that the change will be implemented across all Greggs' 2,600 bakeries in the UK, but it may be rolled out to sites where there are high levels of theft.