Excess weight can disrupt hormonal function and timely ovulation, making it more difficult to become pregnant in natural cycles. It has been found that obesity can lead to a lower success rate during IVF as the number of eggs collected is less in heavier women. Obesity also tends to result in higher occurrence of miscarriages and complications. In Traditional Chinese Medicine, people who are overweight tend to accumulate excessive Damp and Phlegm in their body, which can lead to obstructed circulation in their body as a whole, and the reproductive system in particular.
The first rule of thumb is to keep carbs to the minimum. Eating foods with more fiber is also another easy rule to follow. Exercise regimens vary, but to have 3 days a week with 30mins worth of cardio work is recommendeded, especially if weight is an issue.