I continue my research with some peoples favorite and other's not so much. After reading a lot of the studies it seems that taking 2.5mg EVERY DAY for 6 months reduced estrogen by 45% and DID NOT CRASH IT. Even though the test was done on infertile men they were not on any cycle or aas and it did not crash their estrogen and if anything increased it. Since everyone is different they also di a few other studies as well, another being 2.5mg a week and that seemed to be the best as it also reduced the estro by 40-50% BUT IT DID NOT CRASH IT. The only side effect was seen from aas users that are "cruising" or on all the time such as TRT patients and aas cyclers. The side effect from the drug was osteoporosis and decreases the levels of "good" HDL cholesterol and raises levels of "bad" LDL cholesterol.

Here is the 1st study done:

http://www.ergo-log.com/letrozole2.html

https://www.sciencedaily.com/releases/2015/03/150306102509.htm

Taking 2.5mg a week of Letrozole should be the way it is taken by any aas user on cycle in my opinion

The funny thing is some people complained about "signs of crashed estro" such as joint/bone/muscle pain, tiredness, unusual sweating, nausea, diarrhea, dizziness, and trouble sleeping. Those are not signs of crashed estro when using Letro, those are whats called SIDE EFFECTS. If you get side effects from using letro, that means it is not for you and you have to use another type of AI or stop taking so much.

In the Canadian study, one individual was given Letro at 2.5mg a week for 4 months and had improved signs:

https://www.ncbi.nlm.nih.gov/pubmed/19524225

Now here is something interesting which a lot of people already know and is an excerpt from one of the studies:
Obese men have lower testosterone levels. Because fat mass produces aromatase [the enzyme that converts testosterone into estradiol] obese men are more likely to have problems with reduced libido and depression, in addition to physical problems. Endocrinologists at the Rijnstate Hospital in Arnhem, the Netherlands, discovered that they could change this with surprisingly low doses of letrozole.

In that study they even suggested 1mg a week over the 2.5mg a week.

They even suggest using letrozole instead of other PCT meds for PCT therapy.

In conclusion Bloodwork will always be your friend no matter what but take it for what it is worth here; You cannot crash your estrogen even on 2.5mg a day as it will lower estro by only 45% but you can get nasty side effects from doing it as shown in the study. You can start on 2.5mg a week and then draw bloods to see where you are at. I know a lot of you will question it because they were studies on infertility but you will miss the point; the point being that Letro is an AI that reduces estrogen and they are not going to do a study on a bodybuilder with chemical test going through him or her.

My next one will be about PCT meds as soon as I finish getting as much info as I can...that one is a very touchy subject.

EDIT:

I had to add another study proving that letro does not crash estrogen.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3227911/