UKHospitality chief executive Kate Nicholls also cautioned against the policy, saying it would have a "significant impact" on the sector and particularly on small businesses.
She added: "The knock-on effect would almost certainly mean prices go up and investment in businesses goes down. There is also a serious potential that mandatory calorie labelling would undermine businesses' efforts to tackle food waste, which is a growing concern for consumers and an area of innovation for businesses.
"A blanket introduction of inflexible calorie labelling would represent a serious additional cost for businesses already facing tightening margins and economic instability. It would also represent a considerable burden for those venues that change their menus regularly, some on a daily basis, to incorporate locally sourced produce, seasonal ingredients and specials.
"Small and medium-sized businesses might also find their ability to innovate, particularly when tackling food waste, severely restricted.
"We are supportive of efforts to promote healthier eating habits and the sector is already taking decisive, proactive action to reformulate menus to reduce calories and increase transparency and choice for customers. Many larger venues already include calorie content on their menus voluntarily, with many high street brands providing customers with unprecedented level of information.
"But even larger businesses, operating numerous distinct brands, rely on the flexibility provided by voluntary labelling."
Meanwhile the public is split on the matter - with a recent YouGov poll showing 42% of people believed calorie counts should be compulsory, while 42% did not.