Q: Why can't I seem to lose weight even though I do cardio several times a week?

A: It's a common misconception that several hours a week of cardiovascular (aerobic) exercise will trim your belly, regardless of what other activities you engage in or habits you practice.

The confusion comes from the extreme example of endurance athletes who train at a very high level of intensity and do a large volume of work each week in order to excel in their sport. Runners and cyclists who put in hours of vigorous training usually perform at a level most people never remotely approach.

So, the number of calories they burn during their extended, demanding workouts dwarf the levels most nonathletes exhaust during their exercise sessions. I saw a profile piece during the '08 Summer Olympics that put Michael Phelps' peak training phase daily caloric requirements in the neighborhood of 10,000 per day.

Based on a class I took in college, I estimate my daily needs at 2,500. Most people need less. Some, far less. Does that mean we need to count calories in order to lose weight? Not necessarily.

The weight loss equation is, basically, this:

1. Consume a nutrient-rich (vitamins, minerals, protein and fiber) diet composed of vegetables, fruit, whole grains and lean protein sources.
2. Eat small amounts frequently to satisfy, but not stuff, which will keep your blood sugar stable and minimize over-consumption.
3. Adopt a well-designed, balanced, progressively challenging exercise program that includes strength, endurance, flexibility and core training.
4. Drink plenty of water.
5. Minimize over-consumption and excess or "empty" (nutrient-poor) calories.

Everyone has seen some variation of this list, and there's no denying it works.

One might do well to start with numbers 1 and 5. In my experience with clients over the years, these are the least consistently practiced principles, and the ones most clients are very reluctant or slow to change. But the good news is that they complement each other quite well.

If half your diet is produce (at least half of that veggies), you simply won't have much room left to over-consume comfortably. If the other half is lean protein sources and whole grains, large amounts of empty calories won't be all that appealing.

The reason is that just like we can develop a tolerance for salty, sugary, fatty foods, we can lose that tolerance and become more sensitive to (and less interested in) those heavy tastes and textures with months of "clean" eating.

I have a deep love and respect for exercise science and am passionate about teaching the practice to my clients, students and readers. There's no more effective way to improve your physical vitality and reduce your risk of  many serious diseases than working out regularly.

But, as my fellow trainer and friend (and professional bodybuilder) Tracy Beckham quite correctly observes: "Abs are made in the kitchen."