Yesterday I was watching an informercial for a fitness DVD set that promises miraculous results in 90 days. You know the one I’m talking about: a steady parade of before-and-after photos – but all the after photos look like grinning skeletons with fake tans.

There is such a thing as “too lean”. This fact seems to be lost in a culture that is obsessed with “getting ripped” and “shredded”. When thirteen year-olds earnestly quiz me on how to get a six pack, something has gone awry.

But how do you know if you’re “too lean”? Recommended levels of body fat vary wildly based on the source, and by age and sex. The recommended range for women is 21-34% and for men is 8-22%. Uhhh, there’s a lot of wiggle room in there. Not too helpful.

There are pretty obvious physical manifestations of underfatness but they vary for men and women. In another post I’ll discuss underfatness in men but today I’ll lay out three signs for women.

1) You stop having your period
When your body thinks you’re starving to death it shuts down all functions that don’t directly keep you alive, including fertility and reproduction. If you miss your period and you’re not pregnant, you might be underfat.

2) You don’t need a bra anymore
Your breast is made up of fat and glands. When you lose the fat on your chest the remaining tissue might not fill your brassiere anymore. This is why many female bodybuilders have breast implants.

3) You lose a lot of hair
Telogen effluvium is when you shed hair faster than normal. It’s a phenomenon that accompanies major physical stressors including drastic weight loss. If you lose big chunks of hair while brushing or blow-drying you might have a problem.

So what should you do if you’re getting too lean? If you do CrossFit or you’re a competitive athlete, then you need more carbs than other people. That doesn’t mean you should snarf down donuts. You want to source your carbs primarily from root vegetables like sweet potatoes with a next best choice being fruit.