The internal and external obliques, which I like to call "nature's girdle," are located at the sides of the rectus abdominis. They are the muscles you use when you bend sideways at the spine or twist at the waist. They also contract to compress the abdomen, so you should work them just as hard as you work the rectus abdominis. Adding a twist to crunches works, as well as dumbbell side bends, but be careful not to use any jerky motions, especially if you've had back problems.
Choose Liquid Calories Wisely. Sweetened drinks pile on the calories, but don't reduce hunger like solid foods do. Satisfy your thirst with water, sparkling water with citrus, skim or low-fat milk, or small portions of 100% fruit juice. Try a glass of nutritious and low-calorie vegetable juice to hold you over if you get hungry between meals. Be careful of alcohol calories, which add up quickly. If you tend to drink a glass or two of wine or a cocktail on most days, limiting alcohol to the weekends can be a huge calorie saver.