Your results may vary. Because "going keto" requires you to cut out almost all carbs from your diet - usually less than 5% of your total calories for any given day - it's a pretty drastic overhaul to the way most people eat. Cutting out all fruits and many vegetables, most breads and pastas, and almost all sweeteners ought to lead to a big initial weight drop for practically everyone. If you can stick to that, you'll probably see a big weight loss in your first few weeks.