How to Lose 10 Pounds in Three Weeks

That upcoming event for which you want to look your very best is only three weeks away — but that doesn't mean you can drop a significant amount of weight by then.

Trying to lose 10 pounds in three weeks is ambitious, but doable, especially if 10 pounds is just the start of your weight-loss journey — but it might be too aggressive if you're already at a healthy weight.

Choose proven strategies such as eating whole, unprocessed foods, avoiding junk-food snacks, minimizing alcohol consumption and committing to exercise. Adopt these steps and in three weeks' time, you can make serious inroads toward healthy living, and you can feel lighter and experience greater energy.

Read more: How to Lose Weight Fast for Women

All diets will have you reduce the number of calories to a number that's below the number you burn daily. The Mayo Clinic notes that 1 pound equals about 3,500 calories, so to lose 10 pounds, you'll need to eat 35,000 calories fewer than you burn during those three weeks.

This amounts to a loss rate of a little more than 3 pounds per week, which requires a 1,666-calorie deficit per day. To achieve this deficit, combine physical activity and exercise. For example, do exercises that burn about 800 calories, and eat about 800 calories fewer than you need to maintain your current weight.

Determine how many calories you burn by using an online calculator or by consulting a dietitian. From this number, determine how many calories you can safely subtract. Eating too few calories — below 1,000 to 1,200 for a woman or 1,200 to 1,600 for a man — stalls your metabolism and can be downright dangerous, unless you're on a medically-prescribed plan to treat morbid obesity.

If your planned calorie deficit would take you below these minimums, you should go for a smaller calorie deficit through diet and exercise to increase your daily deficit.

Plan most meals to include 2 to 4 ounces of protein, 1/2 cup of whole grains and 2 cups of watery, fibrous vegetables. For snacks, forgo processed convenience foods, and choose a piece of fresh fruit, celery sticks with a tablespoon of nut butter, deli turkey wrapped in romaine leaves with mustard or a cup of plain, low-fat yogurt.

Ideas for breakfast include half a grapefruit alongside an egg scrambled with mushrooms and peppers and a slice of whole-wheat toast; a smoothie made with 1/2 banana, a handful of spinach, 1/2 cup strawberries, a scoop of whey protein powder and almond milk; or a whole-wheat English muffin topped with 1 ounce of low-fat cheese and sliced tomatoes, placed under the broiler.

For lunch, enjoy a cup of homemade lentil soup with a green salad; grilled chicken breast with 1/2 cup of brown rice and steamed asparagus; tuna canned in water mixed with mustard and capers, with carrot and celery sticks; or plain, low-fat Greek yogurt, a hard-boiled egg and woven wheat crackers with an apple.

Cook dinner at home to avoid large portion sizes and the excess calories you get in restaurant meals. Broil a flank steak and serve with sauteed onion and peppers with corn tortillas, salsa and a few slices of avocado. Roast a fillet of salmon to have with 1/2 cup of wild rice and steamed broccoli.

Make a chili with black beans, canned tomatoes and spices to serve over brown rice with a side of roast zucchini. If you do eat out, look for broiled or baked entrees, and ask the server for steamed vegetables or a side salad instead of fries or a pilaf.

To lose 10 pounds in three weeks without losing considerable muscle mass, you must be physically active. To create the substantial deficit that's required, it is essential to engage in concerted gym activity and to increase your daily movement.

The more you weigh, the more calories you burn for the same amount of activity. Cardiovascular exercise, such as jogging or swimming, burns more than weight training, but both are essential when you're trying to lose weight. For cardio, plan at least 60 to 90 minutes most days to burn enough calories to prompt a 10-pound loss in three weeks.

For example, according to Harvard Health Publishing, if you weigh 185 pounds, a half hour on the elliptical trainer burns about 400 calories. If you weigh 155 pounds, you burn 335 calories in the same amount of time. A very brisk walk at a 4.5-mph pace burns just 222 calories for a 185-pound person in 30 minutes, and 186 calories if you weigh 155 pounds.

If you're new to exercise, trying to exert yourself for an hour or more per day may not be realistic; your weight-loss goal will most likely have to be modified.

Weight training helps you maintain muscle mass as you lose weight. When you lose muscle, your metabolism diminishes, which makes weight loss harder. Go for at least two sessions per week on non-consecutive days. Work every major muscle group, too — including the chest, back, arms, shoulders, legs, hips and abs, with one to three sets of eight to 12 repetitions.

Other physical activity you do during the day helps boost your calorie burn, too. Scrub the floors, do the laundry, walk the dog and pace while on the phone to reach your weight-loss goal.

Read more: Healthy Ways to Lose Weight Fast

If you're already in a healthy weight range but 10 pounds away from your personal ideal, it may take longer than three weeks to lose the weight. The more weight you need to lose, the easier it is to drop 10 pounds in three weeks.

Consider if your goal is realistic and worth the extraordinary effort to reach. Remember, as you get closer to a goal weight, you'll need to make additional changes to your diet and exercise routine to achieve your goal. Losing more than 3 pounds per week for longer than two to three weeks is also discouraged, as it greatly increases your chances of health complications, such as gallstones.

Losing weight at a slower rate may be more doable and may make you less stressed than suffering to reach an impossible goal. When you take time to lose the weight, you're more likely to keep that 10 pounds off for good, rather than cycling through losing and gaining continually.