About 45 million Americans go on a diet each year, yet more than 66 percent of all Americans are overweight or obese, according to Boston Medical Center. Finding a diet that fits your lifestyle and needs is key when it comes to losing weight and keeping it off. Consult your doctor before starting any weight-loss program 2.

Commercial Programs: Weight Watchers, Jenny Craig

Commercial programs cost money but usually offer in-person or online diet support, a specific diet plan for weight loss or packaged meals. Weight Watchers is considered one of the top commercial weight-loss programs, according to "U.S. News and World Report." The program helps you lose weight by teaching you to count food points instead of calories. Jenny Craig is also considered a top commercial weight-loss program due to its one-on-one weekly counseling sessions. In addition to the regular weight-loss meetings, Jenny Craig uses prepackaged meals to help you lose weight.

Do-It-Yourself: MyPlate, DASH

You don't have to spend money to lose weight. The U.S. Department of Agriculture's MyPlate offers a free online weight-loss program. The plan helps you determine your calorie needs for weight loss and provides a balanced food guide, which details what you should eat each day. Dietary Approaches to Stop Hypertension, or DASH, diet is also considered one of the top weight-loss programs. The diet is filled with low-calorie, nutrient-rich foods that help you eat less but still feel satisfied, making it a good choice for not only losing weight, but as a long-term weight maintenance. Like MyPlate, DASH offers meal plans and patterns that provide information on how much you should eat from each food group based on your calorie needs.

Lifestyle Diets: Vegetarian, Mediterranean

The hardest part about losing weight is keeping it off, but a lifestyle diet such as a vegetarian or Mediterranean diet may help 5. A healthy and balanced vegetarian diet is filled with foods that are high in fiber and low in calories, such as:

  • fruits
  • vegetables
  • whole grains
  • beans
  • nuts
  • seeds

Weight loss may be slow but effective at helping you keep it off. The Mediterranean diet emphasizes fruits, vegetables, whole grains, fish and olive oil 5.

Low-Carb: Atkins, South Beach

Low-carb diets are a good way to lose weight and keep it off, according to the Harvard School of Public Health 6. The Atkins diet is considered one of the top low-carb diet plans 7. It is divided into four phases, including a maintenance phase, with specific instructions on what you should eat during each phase. The South Beach diet is also a good choice as a low-carb diet for weight loss. It is divided into three phases and offers heart-healthy and diabetic-friendly options.

Meal Replacement: Slim Fast, Medifast

Meal replacement diets are effective at promoting weight loss and aid in calorie control and meal planning. Slim Fast is one of top meal-replacement weight-loss programs 2. On the program you replace two meals with a shake, and eat one healthy, balanced meal plus three low-calorie snacks. Medifast is a medically supervised low-calorie meal replacement diet that includes ongoing nutrition counseling. This diet plan includes a variety of meal replacement options, including shakes and soups, that you eat in place of most meals and snacks depending on the weight-loss plan you choose to follow.