Ditching a whole dress size in three weeks sounds too good to be true, but not impossible if you're one for liquid-only fasts and carb-banishing regimes

Personally, I like my food. Stick me on a heavily restricted diet and I turn nasty. Trust me, I've tried Atkins and gave in because I missed potatoes and pasta. I've tried the cabbage soup diet and only made it to day three which called for soup, skimmed milk and up to eight bananas - I rebelled with a huge tub of popcorn. And last but not least I tried living on cereal and apples (I was a student at the time with no concept of good nutrition) and was rewarded with bad skin, very little energy and a temper to rival Naomi Campbell's.

All in all it's not a great dieting CV. In fact, having given up trying to follow any fad diets for the past eight years, I've been a much happier, healthier person. However, I'd got very lazy with my eating habits and my waist line was starting to expand, trousers were getting tighter and my muscle tone was next to nothing. I wasn't overweight, but I was a 'skinny fat person'. I looked slim enough with clothes on, but rather flabby round the belly, thighs and hips in the nude. My impending nuptials and honeymoon were enough to goad me into action.

The company promoting the 'Drop a dress size plan' is Dax Moy Personal Training and the owner, Dax, is willing to offer a money back guarantee that anyone can lose this much weight in 21 days if they stick to his diet and fitness regime. With 12 weeks to go before my wedding I was a very willing guinea pig.

Day one of the plan saw me hot-footing it over to the studios in Islington to be measured, walked through the diet and exercise plan and given my Kinetic Chain Assessment (physical profiling) from which a series of corrective flexibility, balance and strength exercises were tailored to fit my body. For example, I have a dodgy shoulder so I was given plenty of strengthening exercises for those muscles.

It was pretty hardcore and my 'leaning' posture and poor stability were highlighted. I felt like a bit of a freak by the end of it, although I was assured that these were fairly common problems for someone who is primarily desk-bound all day. Phew!

The fitness programme

I met with a trainer, Katie Gormley, twice a week for the duration of the three weeks as well as following a series of exercises called Integrated Movement Training twice a day and doing the corrective exercises once a day. Each exercise programme is tailored to fit the individual - mine was a series of squats, twists, lunges, lifts and push-ups - and the focus is on resistance not cardio training. Dax believes that too much low intensity cardiovascular exercise causes muscle loss, which slows your metabolism, the last thing you need when you're trying to lose weight! Short, sharp bursts of activity are the way forward.

The diet

The basics of the diet I followed, scarily named the 'elimination diet', are as follows:

• No caffeine
• No sugar - including sucrose, glucose and fructose
• No processed foods - pretty much anything tinned, baked or pre-packed or if it has e-numbers or unpronounceable words on the packet
• No wheat or gluten products - bread, biscuits, cakes, pies and breakfast cereals
• No dairy - no milk or cheese, but eggs, organic butter and natural organic plain yoghurt are allowed
• No alcohol
• Eat organic wherever possible

Initially, I was fairly horrified. I had never managed to give up booze for a few days let alone three weeks and what was I going to eat? My usual diet consisted of:

Breakfast - packaged breakfast cereal and soya milk
Snack - apple, plum and strawberries
Lunch - tuna or prawn sandwich plus a low-fat, fruit flavoured yoghurt
Snack - cereal bar
Pre-dinner snack - olives and Twiglets
Dinner - Feta salad or pasta and sauce or stir-fry with healthy dollop of soy sauce plus a glass of white wine every other evening and most of a bottle on a Friday and Saturday night.

Apart from the copious amounts of white wine and the rather sugary cereal bar, I thought this was fairly healthy, but I was wrong. It took me most of the first week to get to grips with it, but I soon started devouring recipe books and experimenting with different foods until I'd completely revamped my diet. I finished the 21 days weeks ago, but I'm still cooking the same recipes because I liked them so much.

Breakfast now - Oats, chopped nuts, raisins, dried apricots and seeds soaked in warm water and lemon juice overnight. In the morning I add raspberries and natural yoghurt
Or
Boiled egg with 1 slice of rye bread and organic butter
Snack now - 3 pieces of fruit plus a small handful of unsalted nuts
Lunch now - Prawn and peas with quinoa. Boil and leave the quinoa to soak up remaining water. Add olive oil, cooked peas, prawns and squeeze in the juice of half a lemon. You can also add some toasted seeds like pumpkin or sunflower for a bit of 'crunch'
Or
Rice cakes, ryvita or wheat-free bread with carrot, celery and cucumber sticks and homemade hummus and guacamole or sardines
Snack now - 3 big spoonfuls of natural yoghurt with a small handful of nuts and/or seeds
Dinner now - Some of my favourite recipes:

Chicken stir fry - chicken breasts, fresh ginger, garlic and fresh chillies, with olive oil mushrooms, courgette and red and yellow peppers served with brown rice

Sweet potato and lemon chicken - served with peas, broccoli and asparagus

Corn pasta with homemade tomato, garlic and fresh chilli sauce

3-egg omlette with mushrooms and fresh chillies - served with a green salad, avocado and toasted seeds

Lamb biryani - serves 2 (adapted from The Total Wellbeing Diet)

The list could go on! The great thing is that after the 10 days my cravings for sweet, sugary foods like the cereal bars disappeared. I admit I really struggled going out for dinner with friends. I only did it once during the programme because it was just too tough watching everyone else guzzle wine and devour pizza, and Friday nights without wine were fairly miserable.

However, the end result is a slimmer, more toned, more motivated me. My measurements are below, but they don't tell the full story. Before doing the diet I often felt bloated and sluggish, now my stomach is flatter and my skin is clearer.

I'm a complete convert. I know I probably sound like some mad diet diva, but this is the one diet I've found that works. I'm not a complete saint about it, I've now re-embraced the booze (life without a glass of white wine was fairly dull) but I'm still following the food lessons and recipes I adopted during the 21 days and I don't see this changing.

The Drop A Dress Size In 21 Days plan is available from Dax Moy Personal Training. You can contact the studio via the website or on 0207 354 3550.