Still on course to shed five stone in 12 months? Beth Porter, in her second month, takes up liquidation: drinking herself silly and watching excess pounds drain away ...
Month two of my weight loss plan. Having lost 12lb in the first four weeks with food combining and working out at the gym, I am beginning to have second thoughts about Slimfast forming two-thirds of my daily diet for a month (especially when a friend queried, "That chalky stuff?").

But after a week on the liquid meal replacement, I would guess the company has been listening to its customers. Nothing in the range of products I have tasted has had even a hint of the white cliffs of Dover.

A more practical drawback is that the Slimfast plan requires calorie counting, though some of it is done for you. Two meals a day plus snacks are supplied in a variety of shakes, soups and "nutrition bars" (chewy coated biscuits). This makes up about 600 calories. The evening meal is up to you, as long as it is balanced, no more than 400 calories, and consists of protein, veg and carbohydrate. Important, too, is water consumption - at least eight glasses a day. Water fills you up and flushes you out. It is good for the skin and contains zero calories. Luckily, it is my favourite drink.

The day starts with either a milkshake, of flavoured powder (chocolate, French vanilla or banana) mixed with skimmed milk, or hot chocolate or cappuccino, also mixed from powder. While I would choose none as my desert- island meal, they all justify their description as thick and creamy. And when they tell you the flavour is improved by whisking, listen.

Slimfast powders are not mere flavouring. They contain all the daily required vitamins and minerals, though imbedded in a mixture of sucrose, dextrose and artificial sweetener; plus soya fibre, lecithin and whey. Just like Miss Muffett. If you are wondering how one glass can sustain you until the next meal, Slimfast also contains cellulose, which swells in your stomach, especially with all that water you are drinking.

Today I am up extra early. I have a business meeting and I must allow time for my walk. After cappuccino (whisked to a froth), it's into sweat pants, shirt and trainers. I head off smartly toward Regent's Park: 12 minutes to get there, 15 minutes around the Inner Circle, 12 minutes back home.

Brisk, daily walking is this month's exercise. It is cheap, it aerobically exercises the entire body if you maintain a steady pace, and you need no special equipment. It is hard to measure "brisk", but a good check is a rising pulse rate and a light sweat (be sure you can still carry on a conversation).

If you live in town and are going to walk yourself fit, I recommend a local park. Especially in this weather. The early morning sky pulses with pink, and each day there are changes to leaves and the scampering of animals to distract one from the business at hand.

I march up the elegant Avenue Gardens, round the Inner Circle, marvelling at the patterned flowerbeds. My heart rate is up and my legs are starting to ache, but the scenery drives me on. Quickly - very quickly - past the cafe offering ice-cream. In through Queen Mary's Gate, perspiration popping as I round the pond full of teal, coots and mallards. Over the little bridge and into the most gorgeous display of roses: Ingrid Bergman, Lemon Delight, Polar Star. Out of the gates and into the home stretch. Sweat cools my neck, the pain in my legs is long gone - my lungs feel free. Invigorating.

Home again, I drink some water and am ready to meet the day. Lunch is Slimfast soup, mushroom or tomato. I choose tomato, garnished with Japanese seaweed - something nutritious that does not cost any calories. More water.

At four, I have herbal tea and a snack bar. Slimfast offers chocolate chip, fruit crunch, tropical nut and peanut butter crunch. Very tasty.

My dinner is typical. I could have chosen stuffed tomatoes with mince and rice, sweet and sour pork, or savoury fish provencale from the Slimfast recipe book, but I slightly improvise on one of its chicken and pasta dishes instead. Washed down with ... water.

The weeks roll on. Determined to walk every day, I meet my own challenge, doubling the walk once a week, touring the entire park on a route taking me past the shy, beautiful wolves in the zoo. I admit there are days when I crave a proper meal instead of just a drink. Once I fell from grace on to a croissant. But I went right back on the programme without feeling too guilty.

Meal replacements are patently different from a normal regime, so I was always aware I was on a diet. But for a month it has been helpful; I am feeling better about myself. Especially when I can discern the hint of a cheekbone, I can fit into a bra I thought I would never use again, and the scales say I have lost another 11lb. I'll drink to that - water, of course.