I'm going to disagree slightly with the majority of the comments here and say that excersize is still very important for weight loss.

First off though, because I'm sure some folks are already getting their pitchforks out, all weight loss is CICO, and you can absolutely hit any goal weight just by diet alone without ever getting off your couch. Additionally, what works for weight loss (in terms of actual techniques to achieve a net Calorie deficiency) varies from person to person, what I say below may totally not be the case for you, and that's fine.

All that being said, I think you're going to have a much easier time of it if you also workout in some way.

For one thing, more excersize means more calories out. You can easily (well, your definition of "easy" may vary lol) burn 500 calories during a single workout. If you're making smart eating choices, 500 calories is a lot of food. You would be hard pressed to be physically able to eat 500 calories of an air fried vegetable medely for example. This means that you can lose weight while not feeling starved. And even for less healthy choices, it's still a fair bit of food. You can eat 2 slices of pizza for that one workout and still break even from a calories standpoint.

Basically, excersize = free food - most people fail their diets because they're tired of being hungry all the time and tired of not being able to enjoy the foods they love. Adding excersize into the mix means you can eat more, and still enjoy sensible servings of your favorite "treat" foods while still losing weight.

Secondly, for me at least, working out gives you motivation in the kitchen later. It's a lot harder to cave and order that pizza instead of making the salmon and veggies you had planned for dinner when you know that doing so means "wasting" all that sweat and effort you put in at the gym earlier that day. Remember how earlier I pointed out that a single excersize = 2 slices of pizza? Well that also works the other way around - when you go to reach for a slice of pizza, you wind up asking yourself "is this one slice of pizza worth half a workout?" for me at least, the answer is often no, and even when it's yes (every diet needs room for your favorite junk foods in moderation), I keep asking myself that for each slice, and so will stop eating before I go overboard.

Finally, you probably don't just want to lose weight. OK, maybe you do, idk you - but if you succeed and hit your goal weight, you'll probably just transition to being insecure about fat deposits to being insecure about being scrawny. If your goal is to look good, at least some muscle tone is necessary, and if your goal is to be generally healthier, than it's even more important to add exercise to the mix.

Just my $0.02, Im no dietician or personal trainer, but I've been working hard at getting in shape and have lost 13 pounds in the last month through a combination of diet and exercise, and I truly don't think I could have done it without having added excersize to my routine