Dr Sinclair explained that his beliefs stem from a 1979 study which investigated the rate of nail growth in dogs and humans across several years.
While average life expectancy is around 80 years old in the UK, Dr Sinclair suggests you can indeed age faster than the number of birthdays you have had.
"...We have that graph and actually, looking at thousands of people, we now know for sure that the rate of nail growth decreases about half a per cent per year.
"They glued on these little measuring tapes on to people's nails and measured them over years, in fact," Dr Sinclair explained.
Exercise habits, genetics and eating habits can also affect 'biological age', with a high-fat diet giving rise to oxidative stress and inflammatory damage that may be linked to 'faster ageing'.
