The Promise

Most diets cut certain things out -- like carbs, calories, sugar, or fat -- to help you lose weight. Noom is different. Its a weight loss app that uses a psychology-based approach to change your eating habits for the better. According to its website, Noom uses technology to "help you change not just how you eat, but how you think."

The idea of examining why you eat what you eat, and making changes, isnt new. But the convenience of an app is the key here. That strategy may be why Noom has racked up more than 50 million downloads since it debuted in 2013.

Nooms Healthy Weight Program is a comprehensive wellness plan, with food, exercise, and mental health aspects built in. The idea is to change your behaviors so that you not only take off the weight, but maintain the weight loss long-term.

To start, you download the app and enter your height, weight, gender, age, general health info, goal weight, social circles, and other aspects of your life into it. Then you log your meals and snacks every day. The app gives you feedback on your food choices to help you eat better and reach your target weight.

You also log your exercise. The app has a built-in pedometer to keep track of your steps. Noom offers exercise recommendations to get you moving more.

You'll get regular feedback from a personal coach through Noom's messaging feature. The coach is there to motivate you toward your goal and help you overcome any obstacles along the way. You can also connect with other members through a virtual support group.

Over the 16-week program, Noom pledges to teach you how to make better food choices. You'll get articles each day about nutrition, weight loss, and exercise, as well as interactive challenges to help keep you going. The program also offers advice to help you prevent or manage chronic diseases like high blood pressure and diabetes.

What You Can Eat and What You Can't

No foods are off-limits with Noom, but the app steers you toward choices that are lower in calories and higher in nutrition. To simplify eating, the app color-codes foods -- green, yellow, and red -- based on their nutrient count. Red doesn't mean bad. It just means these foods are higher in calories and meant to be eaten in smaller amounts.

Green foods like these contain the most nutrients, and should make up the bulk of your diet:

Vegetables: Spinach, broccoli, bell peppers

Fruit: Apples, bananas, strawberries

Whole grains: Oatmeal, brown rice, quinoa, whole-grain bread

Dairy: Nonfat yogurt, nonfat cheese, skim milk, unsweetened almond milk

Protein: Tofu

Yellow foods have fewer nutrients and more calories. The goal is to eat these in moderate amounts:

Protein: Grilled chicken, turkey breast, lean ground beef, eggs

Fish: Tuna, salmon

Dairy: Greek yogurt, low-fat cheese

Legumes: Black beans, chickpeas

Grains: Whole-grain tortillas

Red foods are the highest in calories and lowest in nutrients. Eat these less often, and in smaller portions:

Oils: Olive oil, avocado oil, coconut oil

Seeds: Flaxseed, sunflower seeds, chia seeds

Nuts: Almonds, cashews, walnuts

Nut butters: Peanut butter, almond butter

Level of Effort: Medium

You need to log everything you eat, along with each time you exercise, for the program to give you the right advice. If you're pretty tech-savvy, it shouldn't take you more than a few minutes each day. The guidance you get from Noom's coaches can make it easier to stay on track with your diet.

Cooking and shopping? Youll need to do your own shopping and cooking, but the app will give you advice and recipes.

Packaged foods or meals? Not required.

In-person meetings? No. Your Noom health coach is virtual. You message them whenever you need advice.

Exercise? Yes. Log your daily exercise, and Noom will give you advice on the best types of exercises to do.

Does It Allow for Dietary Restrictions or Preferences?

The app's recipes and color-coded ingredient lists include a variety of foods. So no matter what your food philosophy is, from vegan to gluten-free, you should be able to find something to suit your tastes.

What Else You Should Know

Cost. After a free 2-week introductory period, Noom costs $59 a month, or $129 for a three-month subscription. The plan automatically renews unless you cancel it.

Some people have reported issues with canceling. The Better Business Bureau (BBB) has received more than 1,200 complaints from people who say they canceled their trial offer, but were billed $120 or more for several months of subscription service. Because of this issue, the BBB gave Noom a "D" rating. Noom responded to all of the people who posted those issues on the BBB website, indicating that it had issued refunds.

Support. You'll get daily guidance and encouragement from one of Noom's thousand-plus coaches. Its coaches aren't nutritionists -- they're more like behavior-change specialists and people offering encouragement.

Does It Work?

Some research suggests that Noom does help people lose weight. In one study, 78% of people lost weight while using Noom, and 23% lost more than 10% of their body weight.

Dieting is hard, no matter what approach you take. Our society is set up in a way that makes weight loss hard; we live in what experts call an obesogenic landscape, meaning that its hard to avoid gaining weight. So if the daily reminders and tips for cooking, eating, and exercise are personalized, theres a chance that you can be more successful than doing it alone. Setting goals and evaluating and changing behaviors that could sabotage your actions are key.

The Final Word

If youre comfortable with using apps, Noom is handy. Its all on your phone.

Noom is a lifestyle-based approach. It helps you identify what's stopped you from losing weight up to now so that you can make real changes. So this isnt about dropping some pounds for a special event and then going back to normal.

Noom aims to make you a healthier eater overall. That takes effort, whether you do it on an app, use a paper-and-pen journal, or join a real-life support group.

Of course, you have to be accountable. Lying to the app about what you've eaten or how much you exercised won't get you results.

The personal coach can help keep you on track. But if you find it annoying to have someone message you every day, this plan might not be for you.

Noom doesn't take the work out of shopping and cooking. You still have to do that part yourself. But it does suggest what types of foods to eat, and it gives you recipes. That builds your skills in the long run to make those decisions for yourself.

You'll have to spend some money to take advantage of this program. And the ideas here arent new. But if the app would help you learn to eat better and sustain the changes you make long-term, the results might be worth the cost.