You can calculate whether you are moderately or excessively overweight by determining your body mass index (BMI). In other words, you should first find out how overweight you are, and there are online BMI calculators to help you do that.
Overweight treatment is different from the treatment for obesity, in that it is less restrictive and does not include surgery. Set realistic goals and be patient. Keep in mind that it is not healthy to lose more than 2 pounds weekly, particularly in the case of teenagers.
Weight gain may result from burning fewer calories than you take in on a daily basis, either because of physical inactivity or because of an unbalanced diet (this excluding any underlying medical condition). Therefore, you can lose the extra weight when your burnt calories will outnumber your eaten calories, usually by being more physically active. Moreover, by adjusting your diet to include healthier meals and leaving out junk food will also help.
Useful link: BMR calculator
Calculate your daily calorie requirement.
What’s allowed and what’s not
To lose weight successfully, cut out red meat, French fries, chips, sodas; these foods and drinks have huge calorie and fat contents that will ruin your diet.
So, what can you eat? Eat lean meat like poultry and fish, with salad, as well as light soups, low fat yogurt, tomatoes, avocados. In fact, if you are very hungry, it is a good idea to start with soup, and then eat fish or poultry as main course. Between meals, you can snack on a handful of almonds or an apple.
Enter the habit of roasting, grilling, baking, or boiling your food instead of frying it, and don’t skip breakfast. Don’t forget to drink about 8 glasses of water per day; you can also have a yogurt and fresh fruit smoothie once in a while.
Start with 10 minutes of energetic daily exercise and build your way up to 60 minutes each day. Suggestions include weight lifting, riding a bike, going hiking with friends or family. Get enough sleep.
If the person who needs to lose weight is a teenager
Teenagers can also go on a diet, but only as long as they are healthy and follow the doctor’s recommendations. Treatment options can differ when lifestyle changes aren’t enough to help you lose excess weight, and can include weight loss camps and other programs for teenagers.
It is important to maintain your weight and not gain more pounds, because as you get taller with age, you may become naturally slimmer.