If you have lost a significant amount of weight, fallen down the social ladder, or are living as a lonely singleton – then you probably look older.
The combination of lifestyle, medical history and diet has a measurable impact on how your looks age.
Generally speaking a youthful face is an accurate indicator of good health (as is how energetically you walk).
Marriage is more beneficial for a woman knocking almost two years off her age (and if she moves up the social ladder she can look four years younger – and the same applies to men).
For men marriage generally only knocks off one year but having one to three children makes a man look a year younger while it makes no difference to a woman.
These benefits disappear in families with four children.
Looking chubbier as you get older helps men look younger as it smooths out the wrinkles. Adding 2 points to your body mass index (bmi) will take of a year whereas a woman would have to add 7 points to her bmi to get the same effect.
An affluent married man with no more than three children will took ten years younger than someone who is homeless, single and has lost weight (2 points off his bmi).
All the factors combined can lead to people in their 40s looking up to seven years younger than their contemporaries.
Public Health scientists at the Danish twin registry led the study to be published in the journal Age and Ageing.
They asked nurses to guess the ages of almost 2,000 identical and non-identical twins in their seventies. They then looked at environmental factors including marriage, parenthood and social class. Previous studies have shown that non-genetic factors account for 40% of the variation in perceived age.
The effects of heavy smoking are relatively modest. You would have to smoke 20 a day for 20 years to gain extra wrinkles and tobacco smoke only causes half that damage to women’s skin.
However heavy drinking can add a year to both sexes as can diabetes, chronic asthma or the regular use of painkillers.
Excessive exposure to sunlight had no effect on the perception of men’s ages but added over a year to women’s faces by the time they reached seventy.
Depression makes women look a lot older than men. Almost 4 extra years compared with 2.4 for men.
One of the researchers, Dr Kaare Christensen, said “It is a lot more dangerous looking one year older than one year younger”. “If you are not depressed, not lonely, not a smoker, and not too skinny, you are basically doing well”.
Dr Chris Philipson, professor of social gerontology at Keele University says “diet and exercise are crucial factors. You can do an awful lot over the age of 40 to 50 to change the way you experience growing old“.