emeritus professor of human nutrition University of London
The greatest innovation in the field of human nutrition was the Human Calorimeter built by W O Atwater and F G Benedict in a basement room in the Wesleyan University, Middletown, Connecticut, between 1887 and 1899. It was a sealed copper box 2.15 m long, 1.22 m wide and 1.93 m high, in which they measured the energy used by a normal man (their dedicated janitor, Mr E Osterberg), over several runs each lasting four days, with a difference of less than five per cent between replicate runs. The temperature of the room outside the box was kept constant, and heat was extracted from within the box by a system of cooling pipes to keep a zero heat gradient across the walls of the box. Therefore the heat extracted in this water must (over a long period) equal the heat produced by the man inside, and he must have generated this heat by his metabolism.
With modern technology we can measure the metabolic rate of volunteers much more easily, but not more precisely, than was done these pioneering physiologists more than a century ago.
John Garrow is emeritus professor of human nutrition University of London and vice-chairman of HealthWatch