1. Use free weights instead of machines for weight training. If you are unsure of how to use the weights properly, consider a few personal training sessions. Once you get the hang of it you can use unilateral moves to further strengthen your core muscles...even when working arms and legs! Unilateral simply means working one arm or leg at a time. This forces the core muscles to help stabilize the body. I know of one competitive body builder who never specifically worked abs and just utilized unilateral workouts to win numerous trophies.
2. Principle #1 assumes you regularly do weight training. If not...that is a must. Women over 40 and especially peri-menopausal women are more susceptible to belly fat storage due to hormonal changes. Weight training encourages fat loss because as you know muscle mass burns more calories that fat. Jon has a great article in issue 19's "Success For Life" newsletter.
3. Yoga, Pilates and Nia training all focus on the core of the body. Pilates especially is designed for core strength. Yoga positions such as plank and bow poses work both the front and back of the body. Our backs are often neglected in traditional workouts simply because we desire the look of the six pack abs.
4. Nutrition is key in actually being able to visualize the abdominal and back muscles. Refined carbohydrates blanket the body in fat storage due to their lack of fiber and nutrition. When choosing carbohydrates opt for non- processed foods. Nature delivered is a fail safe way to choose. As always, with proteins, choose lean and grilled or baked meats. I really enjoy soy products such as soy milk for smoothie. I also use tofu and seiten for meat substitutes. Fish is a staple (I carry tuna packs as emergency food!) If you are prepared with good food you will make ideal choices. I would much rather have apples with peanut butter or almonds than red licorice....but only if it is available. Unfortunately most quick vending machines don't carry the apple much less the natural peanut butter without the added sugar.