The supermarket chain hopes to address 'pester power' parents are placed under.
The call to ban packed lunches comes amid claims they are contributing to childhood obesity.
By the time they leave primary school children are doing more than an hour less physical activity per week.
Professor Dame Sally Davies has warned the government is currently “nowhere near” its target to halve childhood obesity by 2030.
The move will see Cadbury’s reduce the size of its individual snacks.