Experts have three basic rules for the stomach: step up cardiovascular exercise, watch what you eat, and learn some basic spot work for the tummy muscles.

Unfortunately, there's no way to stop the fat from accumulating in the stomach area, and any cardio work you do will burn fat from the whole body. So it's going to take a mix of exercise and diet to curb the tummy flab.

'Get the engine working,' says Simon Smith, fitness trainer at the Grand Hyatt (tel: 2584 7652), who recommends increasing your workout. 'Put in an extra couple of sessions - it will make the difference in the next few months.'

Any cardiovascular exercise will be beneficial, but running, in particular, can help with stomach muscles, says Sam Hui, fitness manager at Seasons Fitness (tel: 2878 6288). 'If you run, you use the core, because you're transferring the weight from the upper to lower body.'

A bike won't necessarily work the core - unless it's a mountain bike - because you don't need to engage muscles that provide a basis of support to your body. The core muscles are in the trunk region from the ribs to the pelvis.

Pilates and yoga are good at targeting the core area. Research by the Fred Hutchison Cancer Research Centre in the US last year showed that yoga was one way to prevent middle-age spread. The study of more than 15,000 men and women aged 53 to 57 found that those who did yoga avoided the half kilogram most people put on around their stomachs each year between the ages of 45 and 55.

Part of the explanation may be lifestyle. Those who practise yoga are more likely to engage in other physical activity than those who don't, and are also more likely to eat better.

Smith recommends the following pose as a basic core technique to start with: get on all fours, raise your left arm and right leg. 'Extending the limbs makes the lower back work,'' he says.

Making your way to the weights room may also be beneficial. A recent study pointed to the benefits of weightlifting for stomach fat. Kathryn Schmitz, of the University of Pennsylvania's school of medicine, analysed the effects of weight training on intra-abdominal fat - a deep fat that wraps around the organs.

She found that a group of women who did weight training had only a 7 per cent increase in intra-abdominal fat, whereas women who didn't had a 21 per cent increase. Neither group was on a diet, yet overall body fat among those who did weight training dropped by almost 4 per cent.

However, machines (non-weights based) designed for stomach exercises get a low rating from the experts. Smith says they tend to offer too much assistance, rather than making the stomach muscles work harder. Although these machines can help people whose stomach muscles are weaker, he doesn't recommend them all the time. 'It's easy to cheat,' he says.

One of the simplest stomach exercises is the crunch. Hui says the stomach should feel tight when you bring yourself up. 'Don't lock the neck and use that to help,' he says. 'The most important principle is that you have to feel the tummy squeezing.'

Smith says the distance you cover need not be huge. 'When you do a crunch, you want to shorten the distance between the ribs and hip. Don't come all the way up.

'All you're looking for is to get the shoulder blades off the floor and hold the contraction so the muscles are really working overtime.'

By holding the contraction, he means pausing at the top. It's also important not to flop back down - you should go slowly. 'It's all about maintaining control,' Smith says. Quality is the key. It's better to do 10 good ones than 100 bad ones.'

Crunches on a so-called fit or Swiss ball have the added benefit of forcing the core muscles to stabilise while you're crunching. 'When you lie on the ball, you have to use the tummy and core to stabilise yourself,' Hui says. Make sure you're using the right technique, he says. For example, don't have the legs too low (keep them at 90 degrees instead of flat on the floor).

'If you lie on the ball to crunch, you can have a complete range of motion and this means you work more muscles,' he says.

Personal trainer Johnnie Guy of Shape Shifters (tel: 9611 1925) says a quick way to get your stomach into training is to simply hold it in - although this doesn't mean holding your breath too.

'Simply pull your stomach in and hold it,' he says. It not only stops your tummy from hanging or looking distended, but also works the muscles.

Ultimately, however, eating is the key to a svelte stomach.

'The most important thing is diet - beyond anything else,' Guy says.

And the rules are simple: cut out fatty, sugary and processed food and eat loads of fruit and vegetables. Everyone, however, has their preferences as to what works.

'Diet is complicated because people aren't going to stay with something if they're not enjoying it,' Guy says. Yet in the end, when it comes to getting that flatter tummy, 'it's 99 per cent diet'.

For now, it might be worth sticking with the healthy eating option after all.

In last week's lead story, the four-handed massage at the Four Seasons Spa was incorrectly described as the Lomi Lomi. It is the Harmony massage (HK$1,800 for 60 minutes).