High-protein diets. Low-fat diets. Vegetarian diets. No-carb diets. With all the focus on dieting, how do you figure out what's healthy and what isn't?

People diet for many reasons. Some are at an unhealthy weight and want to pay closer attention to their eating and exercise habits. Some play sports and want to be in top physical condition. Others may think they would look and feel better if they lost a few pounds.

Lots of people feel pressured to lose weight and try different types of diets. But if you really need to lose weight, focusing on healthy habits — like eating more fruits and veggies, cutting back on treats, and exercising — will help you more than any fad diet.

Can Diets Be Unhealthy?

Everyone needs enough calories to keep their bodies running well. Any diet that drastically cuts calories or doesn’t provide enough important nutrients can be harmful. Extreme low-fat diets can be bad for you. Everyone needs some fat in their diet, so no one should eat a completely fat-free diet. About 30% of total calories should come from fat.

Don't fall for diets that cut out food groups, either. A diet that says no carbs — like bread or pasta — or tells you to eat only fruit is unhealthy. You won't get the nutrients you need. Even if you lose weight at first, these diets are hard to stick with and don't usually work in the long run.

How Can I Lose Weight Safely?

Eating healthy meals and snacks and exercising can help you lose weight and support normal growth. Regular exercise can help teens feel healthier and better about themselves.

The best way to diet is to eat a variety of healthy food in the right amount. Choose more fruits and veggies, whole grains, and lean protein, and drink water instead of sugary drinks like soda, juice, and sports drinks. Cut back on fried foods, sweets, chips, and other junk food.

If you're concerned about your weight or think you need to lose weight, talk with your doctor or a registered dietitian.

Healthy Habits

If you are ready to make changes, here are some tried-and-true tips:

• Drink low-fat milk and water instead of sugary drinks.
• Eat at least 5 servings a day of fruits and veggies.
• Include a variety protein in your diet. Protein foods — including lean meat and poultry, seafood, eggs, beans, soy products, and nuts — provide important nutrients and help you feel satisfied.
• Choose whole grains (like whole-wheat bread, brown rice, and oatmeal), which provide fiber to help you feel full.
• Don’t skip meals, including breakfast.
• Pay attention to portion sizes.
• Prepare most meals at home. Eating out a lot can cause weight gain.
• Be active every day. Walk to school, sign up for a fitness class, find a sport you like, or dance in your bedroom. It doesn't matter what you do — just move!

Dieting Danger Signs

How do you know if your diet is out of control? Warning signs include:

• continuing to diet, even if you're not overweight
• using diet pills or supplements
• eating in secret, sneaking food, or feeling out of control when you eat
• thinking about food all the time
• restricting activities or avoiding family and friends because of food or need to exercise
• having an intense fear of gaining weight
• vomiting after meals or using laxatives
• feeling weak, lightheaded, or dizzy from not eating

If you, or someone you know, shows any of these signs of an eating disorder, talk to a trusted adult or doctor.