Higher androgen levels help your body gain muscle and the more muscle you have the higher your caloric intake/fat burning is.
Its not just winny, on a test/tren combo if you were to gain only 10 pounds but drop from 15% to 11% you will be harder and have more muscle to burn fat with.
Half this shit is individual genetics. I met some freaks in my life that taken 2g+ wortha' aas and gained little to nothing. One of my close friends is just like that. guy is 5'11'' eats like a horse, trains like a beast, and takes 1g+ aas and he seams like he is not going any where.
Personally i hate winny. Its the only aas that f'ed up my liver values. but thats just me.
Other use it and swear by it.