'My Belly Won't Slim Down'

Q: I'm very frustrated. I see magazine articles promising a six-pack from their easy ab workouts, yet the routines are not nearly as intense as what I do. Even still, my belly is as hard as a rock, but it is still covered with fat. I run five miles three days a week, I do a two-hour weights workout three days a week, and I do around 1,200 crunches (and variations) throughout the day, every day. My diet is decent. I'm over 50. What can I do to get rid of my ab fat?

A: Pummeling your stomach with hundreds of repetitions of ab exercises doesn't achieve what you think it should. Here's why:

Since it takes around one minute to do roughly 20 repetitions of an ab exercise, you are spending up to one hour a day exercising your core. The fact that your muscles are rock solid is testament to the fact that you're stimulating the area and that your muscles are responding. Your six pack is there, but the fat is obscuring it. And all those ab moves won't touch the fat. So, many people blast away at their abs thinking that the burn that they feel is zapping off fat. It's not.

Abdominal exercises burn only slightly more calories than lying on your back and not moving at all. And there's no evidence that what calories these exercises do burn results in spot-specific fat loss in the area. One classic study at the University of Massachusetts found that men who did 5,000 sit-ups a day did not decrease the size of the fat cells in the torso and they did not reduce waist size.

Sizing up your total routine, it's clear that you are spending more of your time doing muscle work than fat-burning work. In total you are exercising for about 16 hours a week. But only three of those hours are being spent doing cardio, the type of exercise that will burn the most calories, and therefore lead to the greatest reductions in body fat. You are spending six hours on a very intense resistance workout and seven hours a week on crunches. You're probably very strong, but if you were to spend more of your exercise time doing cardio work instead, you would burn many more calories.

Let's break it down:

Just to make this comparison, let's assume that you weigh 175 pounds. You will burn around 660 calories running 5 miles in an hour, around 400 calories for every hour of weight lifting, and around 100 calories doing an hour of ab moves. Translated, your regimen burns around 5,080 calories per week. (Keep in mind that this is an estimate; you can't know exactly unless you get measured in a physiology lab.)

This is a nice chunk of calorie burning, and doing the math, adding this amount of extra exercise every week for three months should theoretically have led to an 18-pound weight loss. So, it would be surprising if you have been following this program and not seen any body-fat reduction. That is, unless you are eating or drinking an extra 600 or so calories a day in response to the extra activity (and this could be as easy as one extra sports drink, one extra energy bar and a beer, for example). If you ate around the same amount that you were burning, then you would get fitter, but you would not lose weight.

On the other hand, let's re-jig your routine: You could skip the ab moves altogether, cut your weight-lifting routine by two-thirds, to two hours per week. Now, take those four hours you cut from resistance training and the seven previously spent doing crunches—a total of 11 hours—and use them for doing more cardio (let's say a combination of cycling and the elliptical machine to vary the activity), while also maintaining the three hours of running per week you already do. According to my calculations, this new routine would burn around 8,736 calories per week, leading to a theoretical 30-pound weight loss in three months (almost twice as much as with your old workout!). With the additional weight loss, you should also see a reduction in belly fat.

You should see more fat loss by rearranging your routine to do more cardio. A larger accumulated calorie burn will make the biggest dent in your fat stores. Keep in mind, though, that you must cross-train in order to reduce your risk of injury. And this is simply a theoretical example. In real life you must step up the increased activity gradually and you should not bump up your intensity from three hours of cardio to 16 hours. Try adding an extra 30 minutes a week doing different types of cardio workouts.

You may think it strange that I advise you to ax your ab exercises. That's because you do not need to do crunches, curls, sit-ups, Pilates moves or any other kind of specific ab-muscle strengtheners to exercise these muscles. Plus, there is a real risk of overloading your spine from doing too much ab work. And even if it doesn't hurt your back now, you could be overstressing spinal discs in a way that leads to damage later, especially if you are doing lots of repetitive back-bending motions.

You can get by with skipping ab work because any time you run, dance, play a sport or use a cardio machine like an elliptical trainer, you work those muscles—especially if you try to consciously engage them. Most strength exercises, from pushups to squats to biceps curls, also use your core—particularly if you are standing and/or doing the exercises one arm or one leg at a time (the instability causes the muscles to kick in more). As long as you maintain good posture and try to tighten these muscles to help support your spine as you move, you can save those minutes for exercise more suited to help you meet your fat-loss goals.

Of course, these recommendations are based on what science tells us about the body thus far. But every body is different. And there is always a chance that you are simply genetically predisposed to store much of your excess body fat in your gut, and you may be able to only whittle it down so much. It's easy to gain weight with age in today's environment. And in women, when estrogen levels start to lower, more ab fat accumulates. Certain dietary habits like drinking excess alcohol and eating foods high in saturated and trans fats may also encourage belly blubber.

Get More Fitness Advice From Martica:

• "I Am the Classic Pear Shape"
• Hard-Core Weight-Loss Approaches
• Baby Pudge Won't Budge
• Meet the Experts

Find all articles by Martica.

Do you have a fitness or weight-loss question for Martica? Send e-mail to experts@microsoft.com. Please include Ask Martica in the subject line. Each of our experts responds to one question each week and the responses are posted on Mondays on MSN Health. We regret that we cannot provide a personalized response to every submission.

Martica is a Manhattan-based exercise physiologist and nutritionist and an award-winning fitness instructor. She has written for a variety of publications including Self , Health , Prevention , The New York Times and others. Martica is the author of seven books, including her latest, Cross-Training for Dummies . (Read her full bio.)