Diets may affect fertility both in the short and long term.
Weight related episodes of not ovulating are common and can occur not only in the very light but also in the obese.
The relationship between weight loss and lack of ovulation is well documented and has been observed in young athletes, ballet dancers and gymnasts.
The psychiatric conditions of anorexia nervosa and bulimia are also associated with cessation of ovulation.
The decrease in body fat that occurs in these woman seems to be the major factor.
More subtle abnormalities, however, may occur in women who are light but whose body weight falls below the level at which they can sustain ovulation.
For most women this will occur when their body mass index falls below 19.
Body mass index is calculated by dividing weight in kilograms by height in metres squared.
A normal BMI is between 20 and 25.
Small changes in body weight around a BMI of 19 can make the difference between ovulating and not ovulating.
At the other end of the scale, obesity can also alter ovarian function, and a BMI of more than 25 is associated with increasing episodes of abnormal menstrual cycles.
While genetics plays a role in obesity, and weight loss could be difficult to initiate, there is now very good evidence that relatively small amounts of weight loss can considerably increase the fertility of overweight women.
Infertility problems in women with a BMI between 19 and 30 are unlikely to be associated with weight.
Weight related episodes of not ovulating are common and can occur not only in the very light but also in the obese.
The relationship between weight loss and lack of ovulation is well documented and has been observed in young athletes, ballet dancers and gymnasts.
The psychiatric conditions of anorexia nervosa and bulimia are also associated with cessation of ovulation.
The decrease in body fat that occurs in these woman seems to be the major factor.
More subtle abnormalities, however, may occur in women who are light but whose body weight falls below the level at which they can sustain ovulation.
For most women this will occur when their body mass index falls below 19.
Body mass index is calculated by dividing weight in kilograms by height in metres squared.
A normal BMI is between 20 and 25.
Small changes in body weight around a BMI of 19 can make the difference between ovulating and not ovulating.
At the other end of the scale, obesity can also alter ovarian function, and a BMI of more than 25 is associated with increasing episodes of abnormal menstrual cycles.
While genetics plays a role in obesity, and weight loss could be difficult to initiate, there is now very good evidence that relatively small amounts of weight loss can considerably increase the fertility of overweight women.
Infertility problems in women with a BMI between 19 and 30 are unlikely to be associated with weight.