I believe that a female needs to have a certain body fat percentage to be able to menstruate and have normal fertility. I might be wrong about that but I swear I read it somewhere. You may have hit the magic number or something? Either way it is a good thing that you regained your fertility :)

You are not wrong! If a female is to low or high in weight she will lose your period and put herself at risk for cancer and other health issues.

I honesty feel we are meant to be in the middle spectrum of a healthy BMI, not too low or too high.

A BMI at your hight of 17.7 is underweight and not healthy. A BMI of 19.3 is still the lower end of the spectrum. A BMI of 20.7 is a way better weight for you I feel.

Not that I trust "BMI" totally because it can very between muscle mass etc... It still is just an example that your weight was too low before.

(I have gone from your weights listed to get the bmi's)

I think it's awesome that you are fertile now, it should be a good sign to you that you are doing the right thing ;)

At 5'7" you are at a healthy weight. You may go through some changes in your weight before it settles. As you continue to eat this way you may put on more muscle mass and more normalization with your hormones. This process could take a year or so to complete. Your body was damaged with your previous diet and it will take time to heal.

That's great to hear your period came back, did you change anything else to help restart them or do you feel it was just down to weight? Interested to hear more about why you think they restarted after such a gap.

Do you think that my hormones regulating was the cause of this weight gain or vice versa?

I think they are interrelated. My weight fluctuates with my hormonal cycle, for sure, but fat tissue also has a say in your hormonal state.

Do you get enough animal protein and fat now? That can affect you body composition, and your hormones, too.

I don't think it's a simple chicken or egg question either. I think you put some healthy weight back on and ultimately healed your hormone balance by eating a whole foods, paleo diet with starch and dairy - which is awesome! But achieving fertility probably contributed to your weight stabilizing where it is, as well.

I am a big believer in the body weight set point and believe that body weight and shape is highly influenced by genetics. So yes, somewhat outside our control in many cases. Your weight has fluctuated very little, all things considered, and now that you have returned to the size you were when you had your period before and are eating fantastically, it's not a coincidence that you had a return of fertility.

A BMI of 20 is pretty much perfection for a woman. It's slim, while still having enough mass to have decent strength and adequate resources to get you through illness or pregnancy. Your body is where it needs and wants to be. If you suddenly drop or gain 20 lbs, then you have cause to worry (which you did, thankfully, and corrected things when you went down to 113 lbs). But if you keep eating like this and getting your period, I would bet money that it will never happen. ;)

First of all, congratulations on getting your period back! Amenorrhea (loss of period) has serious side effects, including loss in bone density, and of course, due to lack of ovulation, it is a form of infertility. I am currently being treated for amenorrhea in Finland.

Amenorrhea can be caused by low body weight, over-exercise, stress, disordered eating, as well as by medical conditions such as thyroid problems and poly-cystic ovaries. When it is due to energy deficits, whether through over-training or under-eating, or when it is due to stress, it is usually Hypothalamic Amenorrhea. This can happen even if your BMI is in the normal range, and their are many women whose BMI is low, and yet do not suffer from this. From the research I have read, BMI really isn't the best indicator. Every woman's body is different.

I would say that the weight gain is a necessary part of your healing. The article [Overtraining the Female Athlete][1] recommends:

1. Decrease training intensity/duration by 10%
2. Attempt to increase body weight by 2kg
3. Supplement calcium intake to 1500 mg per day
4. Gain psychological support
5. If amenorrhea is persistent after 3 months of modifying behaviour, gain medical advice.

While this is regarding amenorrhea due in part to over-training, it seems to match with other regimes I have heard regarding recovering from Hypothalamic amenorrhea: I have heard weight gain is almost necessary. Also, it might be good to question if stress or similar had a part to play, and whether that still needs to be addressed

A month ago I added whole dairy and fish back into my diet, and for the last week and a half I have replaced running with walking and yoga. I have seen an improvement in my hormone levels. It was a STRUGGLE to add dairy and fish back into my diet, too-- and to stop running. However, it is also important to remember that amenorrhea can cause bone loss. Diary should help with calcium intake, and FULL-FAT dairy consumption seems to promote ovulation and natural, fertile, cycles.

So, i would guess that the dairy and weight gain are important factors in your recovery. Your body needed, and needs, the excess energy to restore reproductive function. The important thing give yourself time to heal completely, and to consider the menstrual cycle as a important vital sign for the future. The need for increased weight might be a temporary phase needed for healing, but it might also be good to explore seeing the beauty in your still VERY slim but now FERTILE shape.

Amenorrhea is also discussed, helpfully I think, in the book Taking Charge of Your Fertility by Toni Weschler.

Best wishes for a continued recovery!