Tracey burned off around 1,500 calories in an average day, or 1,700 on her most active days.
Volunteer Curtis burned around 2,200 a day, much fewer than the NHS recommendation of 2,500 for a man.
Dr Mosley added: “The studies we’ve done with our volunteers show most of them need 200 to 300 fewer calories than the NHS generally recommends.
“So I’m not convinced these guidelines are useful for everyone.
“With the NHS guidelines, I think they can be helpful for some, but for our five volunteers I think they need a more tailored approach based on their BMI and activity level.”