Q Like many women, I'm pear-shaped: bigger on the bottom, smaller on the top. Even worse, when I lose a few pounds, the weight disappears from my chest and arms, not my thighs or buttocks. Since I don't have much 'up top' to begin with, this seems like a cruel joke. What's going on?

A Just about any woman who has ever tried to lose weight shares your frustration. And if you want to assign blame, look no further than your hormones.

Hormones influence your amount of body fat and its regional distribution. When a girl reaches puberty, oestrogen encourages body fat to accumulate in the gluteal-femoral region (hips and thighs). It's thought that fat stored in this area protected a pregnant woman (and her foetus) against starvation in prehistoric times.

The fat stored in a woman's hips and thighs is also more resistant to breakdown than the fat stored elsewhere, thanks to oestrogen and catecholamines ('fight-or-flight' hormones). It is therefore common for the hip and thigh region to be the first place a woman gains weight and the last place she loses it.

We can't change the fact that our hormones influence our body shape, but we can use the information to tailor our goals:

Get real
Knowing that we're apt to be slightly larger on the bottom, it's unrealistic to hold ourselves to the idealised 36-26-36 standard that dictates identical top and bottom measurements. Focus on realistic weight-loss and body-image goals.

Keep on running
Running is one of the most efficient fat-burning exercises you can do, so keep at it.

Pump up top
Upper-body resistance training can help you define and accentuate the muscles in your shoulders, arms and chest to give you a toned and balanced look.

—Jana Klauer, weight-reduction and nutrition expert