Q: I walk almost every day, but haven't lost any weight. What am I doing wrong?

A: Without knowing the rest of your story, I'd ask you to consider this: how far and how fast are you walking, and do your courses include hills, stairs or soft sand? If not, increase the difficulty of your route and speed up. Also, what are you eating? Exercise is only one part of the weight-loss equation. Walking burns fat, which keeps weight under control, but if you want to lose stubborn kilos you have to look at higher-intensity movement. For example, if a 68kg woman leisurely walks 2.5km in 30 minutes she'll burn 470kJ, but if she runs the same distance in 15 minutes she'll burn 710kJ. Additionally, your metabolism will stay elevated five times longer after a vigorous workout than after an easy one, so make the most of this and push yourself a little harder for better results.

Q: When's the best time to exercise - first thing in the morning or late at night?

A: Some scientists believe the best time is in the afternoon, between 2pm and 6pm, when your body temperature is usually highest, your muscles are looser and flexibility peaks. It definitely makes sense to be weight training at this time. Personally, I like to get my workouts out of the way in the mornings - and a recent US study found that 75 per cent of morning exercisers stuck to their workouts after a year, as opposed to just 25 per cent of evening exercisers. But for many this isn't possible, so choose what's most convenient for you. I believe any time of day is the right time - just as long as you do it!

Q: My husband carries most of his weight on his tummy. What's the best way
to get rid of a potbelly?

A: There should always be a two-pronged attack - diet and exercise. Losing a spare tyre is harder than losing fat from any other area of the body, but it can be done. As a personal trainer I can tell you that successful 'losers' aim for an effort of six to eight, on a scale of one to 10, when exercising. Their tough workouts involve brisk walking including hills, jogging on flat ground or pedalling a bike at 20km/h. If you do these types of activities a minimum of five days a week, for at least 30 minutes each session, then you're giving yourself the best chance of reducing stomach fat.

Nutrition expert Dr Johnny Bowden adds: 'Eat foods that will not raise your blood sugar too high or too fast. This helps create a metabolic environment geared to fat loss.'

Q: It's winter and I'd like to join a gym, but I don't know where to start.

A: Use this checklist to help you choose the gym that's right for you:

• Location: Is it close to home or work?
• Hours: Most gyms have long opening hours on weekdays, but weekends can be limited.
• Reputation: Speak to current members, or check out internet feedback.
• Classes: Are they run at convenient times?
• Contracts/fees: Check the fine print. The first price is often not the best, so bargain for a deal.
• Test drive: Ask for a free week before you sign up. Look at who goes, staff attitudes and involvement, facilities and cleanliness.