Lesson 2: Initial Testing and Diagnosis
Weight and Fertility

Fat – it's just an ugly word, but here we will explore how body fat affects fertility and why how much you weigh is not as important as how much body fat you have.

Models, gymnasts, runners, swimmers – what body image do you have in your mind after seeing that? Thin? Almost no body fat? Fertile or Infertile? I will bet that you didn't think about that last description did you. Whether we like it or not, body fat is needed for proper storage and release of estrogen. If the body fat level is too low, as is found in runners and gymnasts, ovulation cannot occur. The same is true for women with high body fat levels. Because their bodies have too much fat and store too much estrogen, they also do not ovulate regularly or normally.

It's really not a matter of weight, but a matter of body fat percentages. A woman's body fat should be between 17 and 25 percent for menses to begin and continue. For some women, their body fat should be about 22 percent, and for others they can dip as low as 17 percent and still maintain regular periods.

Let's go back to the weight versus body fat. It is very possible to have two women, both weighing 145 pounds and only one of them is fertile. The reason this is possible is because one woman has a body fat percentage between 17 and 25 percent and the other has a body fat percentage between 26 and 30 percent. So, it is not a matter of weight.

What should you do if your body fat percentage is too high? Easier said than done, but losing just 10 to 15 percent of your total weight can make a huge difference. Going back to the woman weighing 145 pounds that has a high body fat percentage. If she were to lose between 14 and 22 pounds, her body fat percentage would be reduced enough to allow her to resume normal ovulation and menses.

Looking at the other side of the coin, a woman with too little body fat needs to increase their weight by only 10 to 15 percent to resume normal ovulation and menses. So, a woman weighing 105 would need to gain 10 to 15 pounds.

There are no hard and fast weight to height measurements that you should go by to determine if your body fat percentage is too low, too high, or where it should be. However, there is a formula that you can use to help you in determining if your body fat percentage should be watched.

The number you get from step 4 is your Body Mass Index. Your BMI should be between 18.5 and 25. If your BMI is 18 or less, and your periods are irregular or have stopped, you need to increase your weight. If your BMI is 25.5 or higher and your periods have become irregular or have stopped, you need to lose weight.

If you would prefer, there are BMI calculators available online. The one available through the CDC is here. This is only a tool to use and does not measure your body fat percentage. However, this will give you a starting point and will let you know if your doctor should test your body fat percentage.