To lose one pound of body weight in a week, a person must consume about 500 fewer calories than he or she burns each day. Here are 18 ways to lose weight without going on a diet.

1. Instead of drinking orange juice at breakfast, eat a whole orange. You'll save about 45 calories.

2. Make your breakfast omelette with four egg whites plus 1/4 cup egg substitute. Replace regular bacon with Canadian bacon to save even more calories.

3. Switch from whole milk to nonfat or lowfat milk. Use sugar substitute instead of sugar in your morning coffee or latte.

4. At lunch, use mustard instead of mayonnaise on your sandwich to save 100 calories (per tablespoon) . Eliminate the cheese and save 100 more calories.

5. Instead of a Big Mac and large fries, go for a plain hamburger and a small french fry and save a whopping 590 calories!

6. Don't eat potato chips at snack time. Have an apple instead for less calories plus the added benefit of more fiber.

7. Substitute diet cola or iced tea for your usual soda. You'll save 150-200 calories per drink.

8. Eat every two to three hours with smaller portions. Don't skip breakfast! Eating small, frequent meals keeps blood glucose levels stable and minimizes the impulse to overeat.

9. Eat more healthy snacks like dried fruits and nuts, fresh fruits, cut up veggies or yogurt.

10. Substitute whole grain foods for white bread, rice and cereals. You will not only cut fat and calories, but whole grains have been proven to reduce the risk of colon cancer by increasing the fiber that your body needs.

11. Saute meat, chicken and vegetables in broth instead of butter. And speaking of butter: replace it with nonfat sour cream on baked potatoes.

12. Instead of Caesar salad, substitute a dinner sald with nonfat salad dressing.

13. Do you love pasta? Have spaghetti with marinara sauce instead of fettuccini with Alfredo sauce. You'll save at least 500 calories!

14. When you're going out with friends, watch your alcohol intake. Instead of using Coke or Seven-Up with your drinks, choose tonic water or seltzer.

15. Restaurants are notorious for their huge serving sizes. Eat only half of your dinner and save the rest for lunch tomorrow. Or simply share the meal with a friend.

16. Get moving. Walk to the store instead of driving. Walking is the best exercise you can do to lose weight.

17. Get more walking time by replacing coffee breaks with exercise breaks. Also use half of your lunch break to take a brisk walk with a co-worker.

18. Swim, swim, swim. By swimming for just an hour you can burn 500 calories. You'll also end up with a firmer, more toned body.

You don't have to go on a strict diet to lose weight. Change to more sensible eating habits and start moving your body by walking, swimming or bicycle riding. You'll be rewarded by good health and a fit body.