Many people want to lose weight. And there are many diet plans that claim to be the best way to help you do this. But before you consider whether to use a diet plan, find out if you really need to lose weight.

A healthy weight is the weight you reach when you're active and eating healthy foods. Many people who weigh a few extra kilograms are still at a healthy weight.

If you practice healthy eating habits and are active enough to stay healthy, then a few extra kilograms are not bad for your health unless you have other medical problems.

If you are thinking about losing weight, ask your doctor whether it's a good idea for you.

Some people lose weight on their own by eating fewer calories and getting active. Diet plans are any kind of structured program you might follow to help you lose weight. There are many different plans, including those in which:

• You follow specific daily menus or you follow rules about what types of food to eat and what types to avoid. These diets often come from books, from the Internet, or from friends or family.
• You buy meal replacements (for example, liquid "shakes") and follow the product's recommendations about what other food you should eat.
• You buy prepared meals that are sent to your home.
• You join a group—in person or on the Internet—and get support and information about how to eat healthy foods.

Ask your doctor about any diet plan you are thinking of using. You should also think about how well you'll be able to stay with that plan's rules about what and how much to eat.

When diet plans work, it's because they restrict calories. Limiting calories by eating smaller portions—not limiting the types of food you eat—is what causes weight loss. Over the long term, diets that focus on limiting carbohydrate or fat will not lead to more weight loss than a healthy eating plan.

Lasting weight loss requires lifelong changes in your eating and exercise habits. If you go back to your old eating habits after you stop dieting, you are likely to regain all the weight you lost on the diet.

Some people are more successful at losing weight when they have a structured plan to follow or when they can participate with a group of people.

A well-balanced diet plan that includes all the food groups may also be a good way to learn about good eating habits. Some plans can teach you about normal portion sizes. They may teach you the importance of eating a variety of healthy foods, including fruits, vegetables, low-fat dairy foods, whole grains, and protein sources such as low-fat meats, beans, and lentils.

A good diet plan will also teach you the importance of eating regular meals, including breakfast. And it will teach you how to change your eating habits for good.

Not all diet plans are safe or effective. Some diet plans can even be bad for your health.

Many diets do not provide a healthy balance of the foods your body needs. Diets that severely restrict calories or that avoid certain types of food may not provide enough vitamins, minerals, and other nutrients.

Most people who diet regain the weight they have lost, and sometimes more, after they stop following the diet plan. Diets can cause people to fall into an unhealthy cycle of losing and gaining weight. This is often called "yo-yo dieting." Yo-yo dieting may be harder on the body than just being overweight.

Just because a diet plan helps another person lose weight does not mean that it will work for you. It is very hard to stay on a diet that includes lots of big changes in your eating habits. If you can't stay on the diet, you may end up feeling discouraged and give up on trying to change your eating habits.