Millions of Brits are clueless about their physical health and have no idea what their blood pressure should be - or even what they weigh, a new study has found. A poll of 2,000 adults also discovered more than half don’t know their blood type, and a further 40 per cent could only guess their weight. Worryingly, 35 per cent of respondents say their lack of body knowledge ‘concerns’ them, but just one in four have any plans to do anything about it. It also emerged the average adult doesn’t begin to take their health seriously until they hit 37, with one in 20 believing they can’t be unwell as long as they remain fit and active.