The prevalence of overweight individuals in the Netherlands is increasing sharply as has also been observed in populations worldwide. In addition to the long-term health risks of being overweight, overweight women of reproductive age are more commonly faced with reproductive disorders. Women who are overweight are less fertile than women of normal weight. The chances of both spontaneous conception and conception after ovulation induction and assisted reproduction are lower in women who are overweight. The chance of a live birth is also decreased due to an increased risk of miscarriage. Furthermore pregnancy outcome is compromised by obesity-related complications of pregnancy. Weight loss of 5-15% in subfertile women who are overweight increases the chance of spontaneous conception and conception after fertility treatment and can be achieved through a low-calorie diet, increased exercise and behaviour modification