A study in adolescents showed no difference between a low glycemic load or low-carb diet and a low-fat diet.
The study included 96 women aged 18 through 40 who were diagnosed with PCOS.
Subjects were followed for one year or until they lost 7% of their body weight.

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In addition, high levels of insulin are believed to increase androgen levels in women with PCOS.
Moran LJ, Noakes M, Clifton PM, Tomlinson L, Galletly C, Norman RJ.
Dietary composition in restoring reproductive and metabolic physiology in overweight women with polycystic ovary syndrome.J Clin Endocrinol Metab.
2003 Feb;88(2):812-9. doi:10.1210/jc.2002-020815
Wong JM, Gallagher M, Gooding H, et.
al.A randomized pilot study of dietary treatments for polycystic ovary syndrome in adolescents.Pediatr Obes.