HS2 train seats will need to be larger to accommodate obese passengers, the network's managing director has said.
Customers are "getting bigger" meaning the trains will have to be heavier and larger than usual, according to the network's managing director of railway operations.
In a presentation to rail industry executives, Chris Rayner said: "HS2 trains will need to offer space for taller people and [allow for] much higher instances of obesity among passengers."
According to the Times, he said companies' responses to the problem of passengers' growing waistlines would be part of the the bidding process for the £2.75bn contract to build 60 trains for the high-speed network.
HS2 is set to link London, Birmingham, the East Midlands, Leeds and Manchester. It is projected to cost £55.7 billion.
There has been some speculation that the network might be dropped by the Conservative government under pressure from backbench MPs from the south of England concerned about the cost.
But on Saturday Theresa May told The Yorkshire Post that the Government was "absolutely committed" to completing it.
In 2011 South West Trains was criticised for making seats in its carriages that were just 43cm wide, leaving little space for larger passengers.
Controversy over expanding waistlines has mostly been focused on small aeroplane seats which do not fit larger passengers, leaving both them and their neighbours uncomfortable.
Last year Airbus designed a bench-style plane seat that could be adjusted to fit a larger passenger.