I've been primal for 20 months.
For the past eight months, I've been bleeding very lightly for a day and a half, with a _total_ blood flow of 5 mL, or one teaspoon. (I use a Mooncup.) My ovulation is otherwise regular, with 10-12 day follicular phases (a little short) and 12-14 luteal phases; I'm not underweight; and I haven't lost weight during the past 9 months. I did the Leptin Reset in February-March and I'm very happy with my current leptin sensitivity--my body knows when it is hungry and when it is not.
I would be delighted about this state of affairs if I weren't trying to get pregnant.
My copper (non-hormonal) IUD was removed nine months ago, and my periods went from regular 28 day cycles with 3-4 days of medium flow to irregular 24-26 day cycles with 1.5 days of scanty flow. I assumed the diminished flow was related to the removal of the IUD and mentally gave it 6 months to recover. Nine months later: Nada.
I no longer think the removal of the IUD is at fault, because there are too many other anecdotal reports of primal/paleo hypomenorrhea floating around out there. I also don't think it's the natural state of affairs for a fertile woman, because 1 teaspoon is just too light to support an implanting embryo.
So: Who else has seen their periods become very light? Has anyone managed to fix it?
For myself, after a fair amount of research, I'm speculating that lack of carbohydrates are at fault, and that my thyroid has slowed down and may be at risk of falling into hypothyroidism. I've been eating 75-100 grams of starchy carbs +berries a day (potatoes, white rice, dairy); this cycle, I'm making a concerted effort to get 150 grams of carbs a day (a LOT of potatoes, plus yogurt, bananas, etc.), and taking Vitex, and starting accupuncture.