Question

I had my baby by Caesarean four years ago, when I was 26, and ever since I've been struggling with my weight. I was 8st before, but now I'm a sturdy 10½st (and 5ft 4in).

I used to be able to diet easily, but these days I find myself failing time and again. I'll lose half a stone, then put it all back on again. I don't expect to look like I did before childbirth, but my formerly flat stomach is now wobbly with cellulite and I am disproportionately big on my bum - a size 14-16 bottom half, to a size 12 top. I feel the impact of my weight every day - I feel less confident, and I know my husband would like me to be slimmer, too.

I used to be quite sporty. Any suggestions?

The personal trainer
Josh Salzmann

Provided there are no medical issues, you should start a lifestyle programme that's about discipline rather than deprivation. Ignore skinny celebs exercising like fiends. When you are as healthy as you can be, you will look your best - and over-exercising or starving yourself isn't healthy. Your basis should be a resistance programme, which will build up your muscles, raise your metabolic rate and burn more calories.

Three to four 45-minute workouts per week is plenty - do simple movements like press-ups and squats until you can't do another successful repetition. Biking, rowing and swimming are good too. Have four to six small meals a day rather than three big ones - eat complex carbohydrates and proteins such as fish and steamed veg, or a palm-sized snack like nuts. In both eating and training, it's about quality over quantity. If you start eating right and exercising properly, you should see a result in a month's time - so stick with it.

· Josh Salzmann's clients include Angelina Jolie and Hugh Jackman (www.salzmann-fitness.com)

The chef
Antony Worrall Thompson

I've tried all the trendy weight-loss plans: Atkins, California, Champagne. Atkins wouldn't work for me long-term. I came across the GI diet when I was diagnosed with a pre-diabetic state due to being overweight and not exercising. It is vital that I still enjoy food, and the GI diet, though designed for diabetics, makes sense for 'normal' dieters too as it's balanced and provides fibre and slow energy-release foods so that blood-sugar levels remain stable and you're not constantly picking. Typical meals would be an egg-white omelette or porridge for breakfast, crab and asparagus fettucine for lunch, Moroccan lamb stew for dinner.

I've lost 2½st eating this way without denying myself. You do need some self-discipline, cutting out cakes and biscuits, but the filling meals make that easier. My tricks are to use spray oil for frying, eat off smaller plates and buy organic when possible. Add a bit of exercise, and I'm sure you'll lose weight.

· Antony Worrall Thompson is a chef and TV presenter. His GI Diet is published by Kyle Cathie at £12.99

The dieter
Kim Robinson

At school, my nickname was Fatty. I've always been a yo-yo dieter and was known as the 'comeback queen' at Weight Watchers because I reappeared so many times. But when I put on 3st during pregnancy, I had to make serious changes. I went from 12st to 9st in 18 months. The reality is, it takes sacrifice. Instead of doing aerobics twice a week, I walked three to five miles a day and took control of my eating. Using the Weight Watchers cookbook, I planned my meals a week in advance with military precision. I still take it on holiday.

It sounds extreme, but if you want to lose weight and you've failed as many times as me, that's how it's got to be. I promised myself fish and chips when I hit my target weight, but the smell of grease was too off-putting - that's how much my eating habits have changed. I'm proud of that. I still haven't got a perfect body, but I'm happy in my skin. Be positive and focused, and you'll be able to say the same.

· Kim Robinson, 39, is a mother of two from Preston and a Weight Watchers leader

· If you have a question for our experts, email health@observer.co.uk