Offshore workers have been told to lose weight as they are taking up too much space on helicopters and lifeboats.
Oil companies Shell and Transocean are targeting workers with a waist size larger than 37ins.
The North Sea helicopter fleet is already under strain because of the grounding of the EC225 Super Puma fleet last year.
The oil firms are working with occupational health company Innovative Health Solutions (IHS) to help employees lose weight.
The average weight of oil workers has increased by three stones (20kg) in the last ten years, according to figures.
In 2005, the Civil Aviation Authority increased the weight allocation for helicopter passengers from 14st (89kg) to 15st 6lb (98kg), meaning more flights have had to be carried out.
Unite union regional industrial officer Willie Wallace said it was wrong to single out oil workers.
He said: "There is the odd guy that has occasionally been told that they could be doing something about their weight. But we could all probably do with losing a few pounds."