^ Jump up to: a b c d e f g h i j k l m n o p q r s Kossoff EH, Zupec-Kania BA, Amark PE, Ballaban-Gil KR, Bergqvist AG, Blackford R, et al. Optimal clinical management of children receiving the ketogenic diet: recommendations of the International Ketogenic Diet Study Group. Epilepsia. 2009 Feb;50(2):304–17. doi:10.1111/j.1528-1167.2008.01765.x. PMID 18823325
While macros will differ a little from person to person, the general rule of thumb for keto is to keep carbohydrates under 5% of your daily caloric intake. As long as you avoid the foods mentioned above, you should be fine. Google “TDEE calculator” if you need some additional guidance on how many calories to eat. I’ve had success following this way of eating as it allows me to eat foods that taste great. There are tons of resources online as well if you need additional guidance. A quick google search should turn up a ton of resources. Hope this helps!
When in the hospital, glucose levels are checked several times daily and the patient is monitored for signs of symptomatic ketosis (which can be treated with a small quantity of orange juice). Lack of energy and lethargy are common, but disappear within two weeks.[17] The parents attend classes over the first three full days, which cover nutrition, managing the diet, preparing meals, avoiding sugar, and handling illness.[19] The level of parental education and commitment required is higher than with medication.[44]

Overall this seems to be a very good diet for most people as far as fat loss is concerned. Some do deal with negative side effects while in ketosis but most people will find that although it's really hard the first two weeks, after that period their body begins to adapt and it gets much easier. Furthermore, one of the biggest benefits of being in ketosis is appetite blunting therefore it can actually be an ideal program for someone on a diet.
I have PCOS as well. Research a PCOS-specific diet. It often overlaps with Keto or Paleo recipes. But you have to also avoid holstein cow produced dairy products, red meat, pork, soy products (which are in almost every processed food) in addition to carbs and sugar. And absolutely avoid anything you can’t be sure doesn’t have extra hormones injected into it (like many mass-farmed meats). Vigorous exercise is also necessary to lose weight when you have PCOS (It’s much, much more difficult for us to lose weight than people with normal hormonal balances).