Losing 20 lbs. in two months falls within the healthy weight-loss goals recommended by the National Institutes of Health, which suggests aiming for 1 to 2 lbs. of weight loss per week. The best way to shed those 20 lbs. will depend on your starting condition. Regardless of what type of exercise you do, your workouts should follow the same pattern.
Workouts for Beginners
If you're not in shape to the point you can exercise at a vigorous intensity for 30 minutes or longer, start with workouts that build your stamina and endurance while you burn calories. You may burn fewer calories in the beginning, but you'll strengthen your cardiorespiratory system and muscular endurance so you can move to higher calorie-burning workouts. Exercise at a pace that's similar to a brisk walk. Use a treadmill at 2 to 3 mph. Ride a bike at 10 mph. Swim laps hard enough to raise your heart rate but moderately enough to let you keep going without stopping after a short time. To prevent muscle soreness, try using two or three different exercises to vary muscle use. Jump rope, do jumping jacks, use more than one exercise machine or jog in place.
If you can exercise at a pace that's similar to jogging for 30 minutes or more, you'll burn more calories than the same amount of exercise done during a beginner workout. For example, walking on a treadmill at 3.5 mph burns about 277 calories in a 160-lb. person, according to MayoClinic.com. If you raise that to 5 miles per hour, you'll burn 584 calories. Try to talk during your exercises -- if you can't, you're exercising too hard and may not be able to finish your workout. Use the exercises from your beginner workouts and raise the intensity.
Losing 20 lbs.
You'll need to burn 3,500 calories to lose 1 lb. of weight. That translates to about 1,000 calories per day to lose 2 lb. each week -- if you're not overeating. In about nine weeks, that translates to 18 lbs. One hour of aerobic exercise, such as cross-country skiing, high-impact aerobics, rowing or swimming, will only burn about 500 calories in a 160-lb. person. Your best bet to lose 20 lb. in two months will be to combine calorie cutting with aerobic exercise each day. Cutting 500 calories from your diet each day and burning an extra 500 calories with exercise provides a balanced approach to long-term weight loss.
Find an activity you will enjoy doing to stick with your workout program. You can increase your calorie burn with anaerobic workouts, such as playing racquetball, tennis or basketball. Use an exercise machine with a heart rate monitor or buy one for yourself to let you keep track of you calorie burn each workout.
Working out every day can be tough on your body. Start with a gradual warmup of several minutes before you hit the treadmill or elliptical hard. This will help warm and stretch your muscles and raise your heart rate to better prepare you for the coming workout. When you're done, don't stop cold -- lower your pace for 5 minutes as you let blood and waste products leave your muscle as your heart rates decreases. Stretch your muscles after your cooldown to further help prevent pain, stiffness and soreness after workouts.