A is for Aaaargh

Ohdeargod – are you really that heavy? Scales must be wrong. You will stop eating dairy, wheat and processed sugar. And next Christmas, you're going to do something healthy like go skiing instead of inhaling vats of brandy butter. The diet has commenced.

B is for 'Bad Science'

The notion of a detox seems like a sensible thing to embark upon at this time of year. Except it's complete rubbish, according to Dr Ben Goldacre, the respected author of book and blog, Bad Science. "The tragedy is that captivated by the distraction of a detox, we avoid the need to think about real, lifelong changes we could make, he writes. So you mightn't want to bother with the lemon juice-cayenne pepper master cleanse after all.

C is for Charcoal

Traditionally used to get rid of poisons from the body, and used in ancient Egpytian times, activated charcoal, which is available from health food stores, has enjoyed an unlikely revival of late. Celebrity champions include Sarah Harding from Girls Aloud, who sprinkles it on her food. Allegedly, it absorbs all kinds of toxins, it's said to be good for bad breath and general digestion.

D is for Dukan

The most hyped diet to emerge in recent years, this way of eating from French doctor, Dr Pierre Dukan. A little bit Atkins, it's low carb, high protein and low fat. You'll eat an awful lot of cottage cheese but he does promise you'll hit your target weight in 34 days.

E is for Eat Right For Your Blood Type

Cheryl Cole says this is how she stays slim and how she has so much energy. The concept is based aroudn the idea that different blood types have different nutritional needs: type O should eat high protein, low carb; type A should be eating mostly vegetarian; type B should have the most varied diet of all and type AB can mix up the A and B diets.

F is for Fitday.com

Fitday is free and it's an infinitely useful web resource for anyone trying to track their weightloss, food, exercise and goals. There's also a journal where you can record why you possibly ended up in Supermacs and it's extremely good at keeping you focused.

G is for the Grapefruit Diet

There's an appealing simplicity to the old school diets, whether that's the Grapefruit sort or the Cabbage Soup Diet. They do work, in the same way that all low-calorie crash diets work if you follow them and they're as based on as much science as the Personality Type diet or the Hallelujah diet, which is based upon 85% raw, organic food and a lot of faith.

H is for the hCG diet

Followers of this inject or drink a hormone extracted from pregnant women's urine, and follow a 500kcal a day diet. Weight loss is meant to be in the region of 1-3lb a day but there's no real evidence that this is as a result of the hor­mone intake and not the calorie restriction.

I is for Instinct Diet

Advertised as the diet for intellectuals, this diet from nutritionaist Dr Susan B Roberts addresses the five food instincts ? hunger, availability, calorie density, familiarity, and variety – and reprogrammes the brain away from the way our ancestors ate (whatever and whenever they could) to the reality of modern life where there's a seemingly neverending supply of fatty, delicious food.

J is for Japanese food

Lots of fish, lots of vegetables, small portions, and the most scrumptious but healthy snack ever, edamame beans, you could do worse than turning Japanese this year.

K is for Kerry Katona

If there was a celebrity poster child for trying every diet out there, it would be the former Mrs Brian McFadden. She's gained, she's lost, she's hit the kebabs, she's stayed off the kebabs, she's had lipo, done bootcamp, brought out an exercise DVD.

Currently in great shape but was allegedly warned by Dancing On Ice bosses not to overindulge over Christmas.

L is for Low-carbing

After a long, long time being told that fat was the enemy, it can be hard to get your head around the fact that fats – good ones – are now fine and it's refined carbs that need to be avoided.

As to whether low-carb is better than low fat? In terms of weight loss, a study published in 2008 showed that a group who went on a low-carb, high-fat diet had much healthier cholestoral levels after 12 weeks than those who embarked on a low-fat, high carb diet.

M is for the Mayer Clinic

The exclusive Viva Mayer Clinic in Austria is holy grail of slimming. It attracts myriad celebrities who are happy to shell out lots of money for their famous cure – a very strict detox that promises half a stone weight loss and glowing skin in a week. The less well-heeled can check out the Viva Mayer book for diet tips.

N is for New Atkins

With Atkins One you didn't go hungry, you feasted on meat and creamy sauces and the pounds dropped off.

But then came the backlash. The founder of the diet died, everyone tired off having disgusting breath and who'd have thought that one day you'd actually crave green vegetables. What's a successful diet organisation to do?

Why, repackage the Atkins diet as the all-new Atkins diet, where healthy carbs like wholegrain bread and brown rice are introduced and lean meats and grilled chicken are espoused.

O is for one-meal a day

Liz Hurley is said to do this, and also Tana Ramsay and Victoria Beckham. There are some studies which show that eating once a day may offer some benefits and only if done for a short period of time. But basically, this is plain old-fashioned calorie restriction, which couldn't feasibly be maintained.

P is for Perricone

Sugar is evil. But you knew that already. Dr Nicholas Perricone is an American dermatologist who believes that not only do refined sugars make you fat, they're also terribly aging.

He says he can recognise someone who starts their day with a sugary espresso and bagel by their slack jawline and general puffiness of features. His 28-day programme cuts out saturated fats and sugars and involves lots of eggs, grilled salmon and fresh berries.

Weight loss is an added bonus to his skin rejuvenation plan and if you're fearful about taking it on as a month long project, he has a three-day version where he promises you'll see results, whether that's a more glowing complexion or even less bloodshot eyes.

Q is for Quinoa

Blame Gillian McKeith. She's responsible for giving this superfood a bad rep, with the same sort of culinary standing as nut loaf. But this Peruvian native is actually amazing, containing more protein than any other grain (although strictly speaking it's not actually a grain) so it will fill you up, with all the essential amino acids, as well as iron, calcium, potassium and Vitamin B6. It's gluten free, too, so it's great for coeliacs. A brilliant rice subsitute and you can even make a sort of porridge with it. Jamie Oliver has a delicious quinoa tabouli recipe on his site.

R is for Rawism

What you'll eat: mainly uncooked vegetables but could also include nuts, seeds, meat (in the form of carpaccio) with myriad health benefits – including weight loss – promised. Risks include food poisoning, vitamin and mineral deficincies and of course, it's dreadfully unexciting.

S is for the Sweetie Diet

Allegedly practised by celebrities such as that role model for clean living, Lindsay Lohan, and Whitney Port. Instead of regular meals you live on a diet of jelly beans and Haribo instead. It's long been a favourite practise among models because it provides a sugar hit and no bloating and it looks kind of cute. Clearly, it's also insane, will rot your teeth and provide you with no nutritional value whatsover.

T is for Trans Fats

To be avoided at all costs. Whatever kind of diet you follow, trans fats are reviled across the board and have no fans. Found in hydrogenated foods like many commer­cially produced cakes, margarines, pizzas, doughnuts and fast food, these raise your bad cholesterol (LDL) and lower your good cholesterol (HDL), so they're as bad for your heart as they are for your waistline. Legally, products don't have to list the presence of trans fats but if see 'hydrogenated oil' or 'partially hydrogenated oil' as an ingredient on pre-packed food, they probably contain trans fats.

U is for Umami

The so-called 'fifth flavour', umami is the Japanese word meaning 'deliciousness'. Found in Parmesan cheese, soy sauce, tomatoes, truffles, aged beef, mackeral and shiitake mushrooms, it plays a role in appetite regulation, its savoury taste creating a fullness of taste that leaves you feeling more satiated. Most recent studies have shown that umami-rich foods may help reduce weight gain. As it's a natural flavour enhancer, it means you need to add less salt to food, always a good thing.

V is for VLCDs

Aka Very Low Calorie Diets, these happen under medical supervision and are suitable for the very overweight. Essentially, you stop eating a normal diet per se and consume approximately 800-100 kcal a day in the the form of meal replacement foods like drinks, bars and soups. They're usually undertaken for less than 12 weeks, and only recommended for those who have already made healthy lifestyle changes and have seen no weight loss and whose BMI (body mass index) is 30 or more. Liptrim, Ligherlife and Cambridge are some companies who offer a VLCD programme.

W is for Weighing Yourself

Popular dieting wisdom would have it that weighing yourself on a daily basis is counterproductive and a little bit Bridget Jones – although you know you are not a number, if it appears that you have gained five pounds between morning and afternoon, you may understandably decide to retire to your bed for the rest of the day. However often you do it, the cardinal rules are: make sure your scales are accurate and always weigh yourself on the same scales; weigh yourself first thing in the morning and on the flat surface; do not attempt balancing act of holding onto side of bath to lessen the load – fooling no one.

X is for the X Syndrome

Defined as a metabolic disorder where you're body is unable to cope with a high sugar diet, it could be the reason why you are unable to shift weight, despite your best endeavours, and it's estimated that one in five suffer from it. It's linked to heart disease and stroke and dietary advice is to restrict foods with a high glycaemic index as well as foods with high saturated fat levels and increase whole fibre foods.

Y is for Yo Yo-ing

The main problem with people's diet plans is that they are unrealistic, result in feelings of deprivations and consequent binging. A more recent, hazardous situation is the mixing and matching of various diets, that completely ignore any of the purported science behind it. So you have baked potato (Weighwatchers) with butter (Atkins) and some pork scratchings (Atkins again) and lots of red wine (some French doctor, for sure). Eh, no.

Z is for the Zone Diet

Jennifer Aniston looks amazing on it. Food wise, you eat as much protein as the palm of your hand, as many non-starchy raw vegetables as you can manage, and enough carbs to keep you ticking over, as well as enough monosaturated oils to stop you feeling hungry.