So you thought dieting and the obsession with weight was a relatively modern invention? Well – no.

Portrait of Charles II, by Sir Peter Lely © The Royal Society


Reading through some minutes of the Society’s weekly scientific meeting on 9 March 1664, I came across a report by Sir Robert Moray of the experiments by His Majesty King Charles II regarding his own weight. Sandwiched in between a reported discussion on the possibility of asking His Majesty for any of his exotic birds which had died so they could be mounted as specimens in the Society’s collections of natural curiosities, and the report of the end result of the mating of a cat and a rabbit, it was treated as a perfectly normal scientific report of the effects of eating – or not. Specifically, it was reported that Charles II:

‘had the Curiosity of weighing himself, very frequently, to observe the severall Emanations of his Body, before and after sleep, Tennis, Riding abroad, Dinners and Suppers: and that he had found he weighed lesse after Tennis, by two pounds three ounces (but the King drinking two draughts of Liquor after play, made up his weight;) after Dinner, more by four pounds and an halfe.’

At this time Charles would have been aged 34, and one wonders what inspired him to this investigation of his weight – did he feel himself getting stouter, or was it just that he felt exercise was becoming harder? Or was it simply curiosity? We do know that Charles II was interested in science – or natural philosophy as it was then known – and he had his own laboratory in Whitehall Palace where experiments were performed.

Those who use running machines or jog must be looking in awe at the amount the king lost playing tennis. And just how much was he eating, that he put on four and a half pounds after eating dinner? I would love to know if this was a banquet, or just his normal dinner, and exactly what was served.

Sadly I have not found any further reference to His Majesty’s experiments in this field. It remains a wonderful example, however, of how the Fellows considered that nothing was too strange to investigate!


  • Roger Barton

    I wonder – was Charles following the lead set half a century earlier by Santorio of Venice, or did he arrive at his methodology independently?