When Exercise Can't Lose

Reflecting the eternal triumph of hope over experience, many Crewsters ask us how to target fat loss: "How do I lose flab from my thighs?" "I want to slim down my waist." "I need to lose these unsightly man-boobs. " That sort of thing.

Alas, we (and that includes you) cannot get rid of fat in specific places. Here's why:

We consume calories. What we don't use for daily energy needs or discharge as waste gets stored as fat. Men tend to amass that fat first in the belly, then elsewhere around the middle, then in the thighs and the upper arms and so on, explains William O. Roberts, an associate professor in the Department of Family Medicine at the University of Minnesota Medical School and a past president of the American College of Sports Medicine. For women, fat accumulates first in the butt and thighs and then settles elsewhere.

When we need energy, our bodies turn first not to those stores but to the glycogen in our bloodstream that we have produced from recently consumed calories. When that's used up, we tap into our fat stores (oh, the unfairness!) in reverse order: For women, the fat disappears from the perimeter before the mother lode around the hips gets tapped. For guys, the fat disappears first from the upper arms, then the thighs, then the midsection.

"Essentially, the fat stores are like your bank and [the glycogen] is like your wallet," Roberts says. "You go to your wallet before you go to your bank." And when you get to the bank, you withdraw your most recent deposits before your oldest ones.

So even if you're a guy who does, say, 12,000 crunches, your body will not start to access the insulation surrounding your abs until other, more recently deposited fat is expended. Ladies who do butt-blasters will lose the rim under the chin before thigh circumference.

Bummer, yes, but there is hope: To lose fat you simply (let's make that "simply") must burn more calories than you consume. If you want to lose weight, shoot for a daily deficit of 200 to 300 calories -- achievable, Roberts says, by consuming 100 fewer calories and burning 100 to 200 more per day than usual. A pound of fat equals 3,500 calories, meaning you can safely lose a couple to a few pounds per month.

Don't try to outsmart the system by, say, running a deficit of 2,000 calories a day. "The body works to hold onto fat if you try to starve it," Roberts notes.

He prescribes 40 to 60 minutes of "fairly intense exercise" -- boosting your heart rate to 60 to 80 percent of maximum -- three or four days a week. (Maximum heart rate in beats per minute is roughly estimated by subtracting your age from 220.)

On the other days, Roberts says, you can go a little shorter and less intense -- take a 20-minute walk or do some light physical work. "You should be getting some activity almost every day."

As for what's underneath the weight you'd rather not carry: You can, and should, target muscles for strength building, whether they are protected by a sheath of adipose or not.

Strength training causes small tears in the fibers of the muscles employed and, when the body shuttles protein to the muscles in response to the stress, those fibers grow.

So: Cut calories and exercise more to lose weight all over. Build muscle to tone what's underneath. Continue until satisfied. In the meantime? We think you look great.

No chat this week; email is move@washpost.com .

-- John Briley