To lose 7 lbs. in two weeks, you'll have to cut a significant number of calories from your diet or burn them through exercise. To lose 3.5 lbs. per week, you'll have to cut 1,750 calories from your diet each day. If you are overeating, especially eating lots of junk food and soda, this may be possible. The recommended rate of weight loss is 1 to 2 lbs. per week, so don't expect to maintain this rate of weight loss for the long-term.
Eliminate all sweetened drinks, chips, chocolate and fast food from your diet. These foods are high in calories and low in nutrients. You can easily eliminate hundreds of calories from your diet by not consuming these foods.
Base your meals around vegetables and protein. Vegetables have very few calories and plenty of fiber and nutrients, so you can fill up on lots of them without gaining weight. Protein helps you feel full so you won't snack or overeat later. Choose lean protein such as chicken and fish.
Reduce the fat in your diet. Cooking with oil and butter, using salad dressings, and having peanut butter are OK in moderation, but not when you're trying to lose weight. Each tbsp. has between 50 and 100 calories, so you can lose a lot of weight by reducing or cutting out these fats.
Drink water. Water is a calorie-free way to keep you hydrated. It can also help you feel more full if you drink a couple of glasses before a meal, you may eat less. If you replace high-calorie drinks such as soda with water, you'll reduce your caloric intake even more.
Exercise every day. Do cardiovascular exercise, such as walking or cycling, every day, and lifting weights two to three times per week. Boost the calorie-burning by adding intervals to your cardio workouts, in which you go really hard for a couple of minutes, then recover, and repeat. When lifting weights, do a circuit in which you switch weights to another muscle group during your recovery. This will raise your heart rate and burn more calories.