Whether you're trying to fit into a wedding dress, getting ready for swimsuit season or preparing for your 20-year school reunion, sometimes you need to lose weight in a short amount of time. However, even if you only have 13 days to lose weight, it's important to do so in a healthy way to protect your body against the possible consequences of losing weight incorrectly.
Set a goal for yourself in order to achieve a calorie deficit. A calorie deficit occurs when you burn more calories than you take into your diet. Take the amount of weight you want to lose and divide it by 2 to get your weekly weight-loss goal. Take your weekly goal number and multiply it by 3,500 -- which equals a pound -- to get an approximate deficit you need to achieve to meet your weight-loss goal.
Follow a set amount of exercise each day in order to help reach your deficit goal. The Centers for Disease Control and Prevention recommends that all adults strive to get at least 150 minutes of moderately-intense exercise each week. However, for better results, the CDC recommends 300 minutes of moderately-intense exercise, or 150 minutes of more intense exercise. Keep track of the estimated number of calories burned by using tools such as LIVESTRONG.COM's MyPlate fitness tracker.
Include strength training to increase strength and calorie-burning efficiency. Experiment with different forms of strength training such as barbells, dumbbells, kettle balls, weight machines and natural resistance exercises such as pullups, situps and pushups. Keep track of calories burned from strength training like you do with your aerobic exercise.
Balance the calories burned with the calories you cut from your diet. After calculating how many calories you plan to burn through exercise each week, subtract that number from the total calorie deficit you need to create. The remaining portion of your calorie deficit needs to come from removing calories from your diet.
Meet your dietary calorie goal with foods that are dense in nutrition. This includes foods like whole grains, lean proteins, fruits, vegetables and low-fat dairy products. Eating nutrition-dense foods ensures that even though your dietary goal may be lower than normal, you are still getting all the macronutrients, vitamins and minerals your body needs to function properly.