I don't know how to increase estrogen levels in normal weight women. But you can definitely lower estrogen levels, by dropping below a certain body fat percentage. In fact, at some point, a women will lose her cycle if she's too skinny and wont be able to get pregnant.
My ex girlfriend had six pack abs, was a very fit person. Probably top 1% of all women. I suspect that my girlfriend was able to achieve her six pack abs for 3 reasons. Had a meat/low sugar/low carb diet, and did a lot of swimming. But I suspect, the biggest reason was that she probably had higher than average testosterone levels for a woman. That also had the knock on effect of her liking exercise more.
You make a good point. I think of these more like a feed back loop. One can affect the other. You can spiral up, or spiral down.
Some people might be genetically predisposed to become Alcoholics. Once you start drinking more, it will make you more of an alcoholic. Drinking less, will make you less of an alcoholic. Social pressure might help you drink less, or drink more.
Its not inconsistent.
My ex girlfriend had six pack abs, was a very fit person. Probably top 1% of all women. I suspect that my girlfriend was able to achieve her six pack abs for 3 reasons. Had a meat/low sugar/low carb diet, and did a lot of swimming. But I suspect, the biggest reason was that she probably had higher than average testosterone levels for a woman. That also had the knock on effect of her liking exercise more.