Oh, to be a celebrity—fame, fortune, and the ability to have personal trainers and nutritionists on speed dial when you want to lose a few pounds.

For mere mortals, however, weight loss isn’t quite so easy. (Actually, that’s generous—losing weight is hard AF.)

That’s where Noom comes into play—a fitness and weight-loss app touted as “Weight Watchers for Millennials.” But uh, what does that even mean? And what makes Noom any different than any other weight-loss program or app out there?

Noom? That’s kind of a weird name. What is it?

So, Noom claims to be the “last weight-loss program you’ll ever need,” according to its website. It’s like having a trainer, nutritionist, and health coach all in one place (i.e., your phone).

Where Noom differs from other apps, however, is its focus on making behavioral changes surrounding dieting and weight loss.

The app will show you, for example, the best foods to eat (it rates them on a scale from green to yellow to red). It’ll also prompt you to read tidbits on healthy habits and rate your motivation—and will quiz you after.

Honestly, it sounds kind of like a drag (who has time to read and take quizzes throughout the day?), but it could be the key to successful, sustained weight loss.

“The education elements of the app, such as reducing and understanding calories and carbohydrate intake, increasing physical activity, and gaining nutritional knowledge is imperative,” says Dr. Sue Decotiis, MD, a physician at NYU Medical Center and Lenox Hill Hospital.

It also has the ability to provide support and feedback from others doing the program—all 45 million of them. And it’s not just message boards or automated blurbs—you can actually talk to others in a group chat in real time.

(It should be noted, too, that Noom provides users with “health and wellness coaches” that are approved by the National Consortium for Credentialing Health & Wellness Coaches—though that doesn’t necessarily mean they are trained professionals like registered dietitians or certified trainers.)

“The on-demand rewards from the behavior modification and the social support have been shown to bolster an individual’s success,” adds Decotiis.

Okay, so what happens when I download the Noom app?

When you first download the free app, Noom asks how much weight you’d like to lose, how fast you’d like to lose it (on a scale from tortoise to hare), plus your age, height, and current weight—all pretty standard diet-tracking stuff.

From there, the app asks for permission to access your smartphone’s Health app. It automatically logs your exercise, but asks you to log everything you eat during the day (the app has a database of foods to choose from). Noom actually takes those calories and subtracts them from a daily calorie goal (depending on those factors you shared with it earlier) to show you how many calories you have left in the day.

via What Is Noom and Can the Diet Help You Lose Weight? Nutritionists Answer