What's behind belly fat

Your weight is largely determined by three main factors:

• How many calories you consume during the day
• How many calories you burn off through daily exercise
• Your age

If you eat too much and exercise too little, you're likely to carry excess weight — including belly fat.

Also, your muscle mass might diminish slightly with age, while fat increases. Loss of muscle mass also decreases the rate at which your body uses calories, which can make it more challenging to maintain a healthy weight.

Many women also notice an increase in belly fat as they get older — even if they aren't gaining weight. This is likely due to a decreasing level of estrogen, which appears to influence where fat is distributed in the body.

The tendency to gain or carry weight around the waist — and have an "apple" rather than a "pear" shape — might have a genetic component as well.