Give me an idea of how long it will take?

Well, you're going to destroy your metabolism eating that little (MFP is absolutely terrible about this) so who knows

Exercise isn't where you lose weight. It's all in the diet, so if your diet is full of sugar/carbs you are not going to see a lot of changes.

If you lose 1lb a week and everything just happens to go right and work for you. Then 200 to 170 should be 30 weeks. 170 to 150 is 20 weeks. It really won't happen like that though. You'll lose water weight in the beginning and then probably stall a few times.

It really depends but I know that on my diet (keto) I lose about 1.40lbs a week depending on how much water I'm able to intake (usually around 1.80 if I get my 4 liters).

Actually not really. I eat the right macros and make sure I get enough protein. I haven't lost any muscle mass.

Yeah, you might lose quickly but it'll be so much muscle. And you'll probably be hangry (depending on how much exercise you do to get more calories).

This link to Scooby's is nice because you can easily play around with deficits and see what they work out to for a year (on average). The method is different - TDEE - which is where exercise calories are included, so no eating anything back on different days. Take the (TDEE - some percentage) and that's how you get your deficit. Play around. And poke around his site. I like him There's a little bit of dubious science, but the man can clearly help most of us, lol!

edit: the link, duh! http://scoobysworkshop.com/accurate-calorie-calculator/

Don't eat less than your BMR unless you are extremely heavy (high bf% I mean), and try not to even net below it if you are concerned about preserving muscle and feeling your best.

Of course, lift some weights (or hard bodyweight moves at least). That's just so important for so many things. Minimum twice a week. Really Good luck!

Thanks lovely folks. I have a good treadmill at home and a lot of space to workout , but I have no weights and don't really want to go to the gym. Any way I can strength train at home?

Definitely! Start with yoga, imho, and then there are advance yoga positions, for one route (I do). Folks also suggest nerdfitness for their bodyweight programs and You are Your Own Gym. Also Convict Conditioning.

I do yoga, some gymnastics, and tough dance moves (the training, anyway) that require a lot of strength. Basically, if you can progress with the difficulty, you are good. If you can do it easily, it's not going to do strength training for you (not that it's bad just to get the blood flowing, etc).