Many people understand the health risks of being overweight or obese as these conditions have been linked to cardiovascular disease, stroke and a host of other illnesses. However, it might be said that less attention is paid to the fact that being underweight is actually more dangerous than being slightly overweight.
 
It has been found that having a BMI lower than 18.5 puts you at greater risk of illness than those with a BMI of 25 – 29.9. People who are underweight are prone to developing weak immune systems, due to the fact that their nutrient intake is not high. Also, low muscle mass, osteoporosis and anaemia are common symptoms of people who regularly stay in the 'underweight' bracket.
 
In 2006 the London School of Hygeine and Tropical Medecine found that being underweight can also have severe implications for pregnant women, reporting that women with a BMI less than 18.5 were 72% more likely to miscarry in their first trimester.
 
The team looked into the cases of 600 women who had miscarried and a further 6,000 women whose pregnancies continued past 12 weeks. As well as finding that underweight women were more at risk, they also found that women who took vitamin supplements during early pregnancy halved their risk of miscarriage by 50%.
 
Noreen Maconochie, a senior lecturer in epidemiology and medical statistics, who led the research team, said: "It is likely that advice to encourage a healthy diet and to try and reduce stress and promote emotional well-being might help women in early pregnancy, or those planning a pregnancy, reduce their risk of miscarriage."
 
In order to calculate your BMI, find a useful calculator at the National Heart Lung and Blood Institute site: http://www.nhlbisupport.com/bmi/