1000 calories a day is way too low. Your body will go into starvation mode and actually try to prevent you from losing weight. It'll cannibalize muscle mass along with fat. You'll feel fucking terrible and you'd actually do damage to your body if you kept it up too long. Aim for a 20-25% calorie reduction, which for the average overweight man should be closer to 2000kcal. Use
this to calculate your own figures.
Keto is effective but it comes with a lot of caveats. Getting into ketosis is an involved process for your body, there is a possibility you'll feel poorly when starting the diet or even all the way through it. A single spoonful of the wrong stuff'll knock you right out of ketosis, so you will need to map out your meals methodically and prepare all of it yourself. You can pretty much rule out eating out at 99% of places, even the ones that market themselves as keto-friendly. A lot of people equate keto with an all-meat diet but the reality is you're gonna have to double or triple up on your leafy greens to make up for all the fibre and micronutrients you've removed from your diet or you'll feel miserable.
You have to be fairly disciplined and studious to pull keto off. Don't be one of those dummies like JoeH or Jack Scalfani who use the diet as an excuse to shove mountains of bacon in their face. The latter suffered through three strokes, a paralyzed and withered arm and thyroid and leg surgery because he spent the last couple of years lying to himself, and he is currently in the ICU courtesy of his second, better heart attack.