But is there more to this than simply a lack of willpower? Once upon a time, I studied astrology and used to write the odd column or two for some well known magazines. After a long absence, I've revived my interest in matters horoscopic, and it got me thinking: could my starsign be making me fat?
Actually, as a Pisces, I've definitely a reason to blame it on the zodiac: Pisces has the least willpower of anyone, and adores forbidden fruit, particularly the kind that's eleventy three thousand points at Weightwitches.
So I dusted off the text-books and did a little swotting, and I reckon the zodiac might have some helpful advice for those looking to shed a few pounds for summer, whatever their sign. So without further ado, here is the Mrs Trefusis Guide to Astro-dieting....
CANCER: June 22-July 23
Are the stars on your figure's side? Food dictates your emotions - you get moody if not fed regularly, or if denied your favourite comfort foods. But you're fit and strong and can burn off big meals if you want to.
Most likely to make you fat? PMS sends you insane with desire for chocolate and sweets every month. And watch out for emotional crises: for Cancerians nothing comforts better than cake.
Eat right: Stave off cravings: to alleviate your food/emotion thing, make sure you're getting enough B vitamins (deficiency is linked to depression). B for instance, in bananas, avocado and fish can ease PMS symptoms.
Maybe it's because I'm Cancerian? Childhood habits linger with you, so if you always had to clear your plate, or were never allowed sweets, chances are you're still obeying mummy.
LEO: July 24-Aug23
Are the stars on your figure's side? For proud Leos, thinness has nothing to do with health - it's all about looking fabulous and wrigging into designer clothes.
Most likely to make you fat? Your love of good living conflicts with your glamorous side: but you can bet your bottom dollar (or just your bottom) that Leo Jennifer Lopez had to choose between a passion for fine dining and wearing skinny jeans
Eat right: If you've overindulged, try a detoxing juice fast. Three days will have you bright-eyed and busy-tailed. Watch the fat content of your favourite foods: Leo rules the heard, so steer clear of no-carb diets that narrow your arteries as well as your hip measurements.
Maybe it's because I'm a Leo? Leos like individual attention - a personal trainer will give you the encouragement to strive for faster results
VIRGO: Aug 24-Sept23
Are the stars on your figure's side? Virgos are the health freaks of the zodiac: you're body aware and health-conscious. But you can overdo it, leaving you prone to food intolerances.
Most likely to make you fat: Virgos tend to be slim - all that nervous energy. But you can feel fat from bloating if you have food sensitivities.
Eat right: You have energy slumps - try eating little and often to even out the gaps. Food combining is an old fashioned solution which might just help if you suffer from that bloated feeling.
Maybe it's because I'm a Virgo? Your eating goes awry when you're stressed, and since you're the worry monster of the zodiac, this can be often. And of course, for you, the devil's in the detail - if you suspect you might have allergies, keep a food diary.
Are the star's on your figure's side? Librans like to look beautiful in a shapely, womanly way. Just as well, as you have a sweet tooth and a reputation for laziness.
Most likely to make you fat? Just about everything. But you are the best-looking sign, even if you are bone idle - you'd take liposuction over gym sessions any day. You're also brilliant at persuading yourself that struggling into a pair of Spanx is easily as effective as working out with one of those power bands.
Eating right: You like to look good in clothes, and this may necessitate some sacrifices. be a food puritan: if it's fattening, just don't buy it, because like your fellow Libran, Oscar Wilde, you can resist anything except temptation
Maybe it's because I'm a Libran? Libra is, of course, the sign of the scales - try for a balance. If you overdo it one day, cut back the next.
SCORPIO Oct 24-Nov 23
Are the stars on your figure's side? You have plenty of willpower, though you can keep it hidden. You either treat your body as a temple, or abuse it mercilessly.
Most likely to make you fat? You've got self-control, but you think moderation is for wimps - so you go for a big blowout just because you can. You also love hot, spicy food, and red Thai curries are hardly lo-cal.
Eat right: Flush out toxins: eat cleansing foods like stewed apple and drink lots of water. Try a detox fast once in a while, and colonic irrigation may be useful.
Maybe it's because I'm a Scorpio? Go for challenging exercise, like distance running - as the most intense sign, you'll push it to extremes. An ulterior motive also works for Scorpio motivation: remember that the running club is often full of tasty blokes.
SAGITTARIUS Nov 23-Dec 21
Are the stars on your figure's side? Sagittarius rules the hips and thighs - all you consume may go straight to the bottom line. You do overindulge, but on the plus sign, Sagittarius is the most naturally sporty of all the signs.
Most likely to make you fat? The party lifestyle gets Sagittarians every time - you're the bon vivant of the zodiac. Um, how many units did you drink this evening?
Eat right: Watch portion size. Jupiter, your ruling planet, likes nothing so much as a plate heaped with food, so avoid the 'all you can eat buffet' like the plague.
Maybe it's because I'm a Sagittarian? Your sign rules foreign things and adores the exotic. Swot up on the calories in a Tikka Masala before nipping down the 'Taj Mahal' on a Friday night.
CAPRICORN Dec 22-Jan 20
Are the stars on your figure's side? You've got serious self-control on the one hand, but the ability to be horribly self-critical on the other. Somehow, slim is never slim enough. Don't let yourself be undermined by your own high standards.
Most likely to make you fat? You're a very traditional eater: meat with potatoes, followed by a proper pudding. And you do love pudding.
Eat right: Be strict. You have appearances to keep up and your ruler, Saturn, give you restraint. If you're a workaholic Capricorn, and many are, plan ahead and make a healthy sandwich to bring from home for lunchtime so you don't ever have to leave your desk.
Is it because I'm a Capricorn? Capricorn rules the skeleton, so don't forget to keep your calcium intake high with low-fat dairy. According to the latest research, dairy products also help keep the weight off too.
Aquarius Jan 21-Feb 19
Are the stars on your figures side? Aquarians have a reputation for being interested in food first and foremost as fuel, and get geeky about nutrition. But even Aquarians find protein shakes with a wheatgrass chaser fail to hit the spot. And then it all goes to pot.
Most likely to make you fat? Yo-yo dieting is the Aquarian curse: you find fad diets irresistible - you name it, you've tried it, from Alli to Atkins. And when the pounds pile on again, you're on Amazon, scoping out the latest bestseller.
Eat right: Use your inquisitiveness to educate yourself about food and nutrition, so you can make more of an informed decision about what the diet books are selling you.
Is it because I'm an Aquarian? Sometimes you just think food is irrelevant: in the Aquarian vision of the future, we'll all be eating pills instead. But in the real world, remember that you have the self-control of a Capricorn and the willpower of a Scorpio: yes, one day you will make it from pig to twig.
Pisces Feb 20-March 20
Are the stars on your figure's side? Poor Pisces - you're the sign for whom the phrase 'the road to hell is paved with good intentions' was invented. You get it both ways - you're ruled by Jupiter, so you share Sagittarians love of giving it large, and by Neptune, so you also quite like to use food and drink in an, ahem, medicinal capacity. Three martinis to the wind and it's your canape hell.
Most likely to make you fat? You hate to hurt people's feelings by saying 'no'. Stop it- people will still like you if you refuse a second helping, or admit you're on a diet.
Eat right: You don't have an inbuilt 'stop' mechanism. If you ate til you felt full, you'd never leave the table. Set yourself limits.
Is it because I'm a Piscean? Most Pisceans use the excuse that trainers are too ugly to avoid getting into gym kit. True, but running in kitten heels is very dangerous.
Aries March 21-April 20
Are the stars on your figure's side? Lucky you. You're energetic, always on the go. Food is fuel to burn off as you rush through the day. What's more, your sign likes exercise, even if you don't. And you also tend to get quick results. Most gratifying.
Most likely to make you fat? You can be tempted by fast food, mainly because you have a temper tantrum if you don't eat the minute you realise you're hungry. Your idea of a well-stocked kitchen is one with a selection of takeaway menus.
Eat right: You need carbs to keep your energy high, and to stop yourself being ambushed by hunger. MacDonalds is not the answer.
Is it because I'm an Aries? Aries likes their exercise action packed, fast, furious and challenging, so if you're feeling bored by pilates and frustrated by yoga, try kick-boxing instead. You're also very goal oriented, so diets work best when you set yourself deadlines like x number of pounds by x date.
Taurus April 21-May 21
Are the stars on your figure's side? You only have to look at spaghetti carbonara on a menu for it to show on the scales. The stars gave you an appreciation of good food, fine wine and nice restaurants and your idea of exercise is walking to the car. Oops.
Most likely to make you fat? Feeling like you deserve a treat. But don't reward progress with food: take yourself shopping for beautiful clothes instead.
Eat right: You do have willpower, and that legendary Taurean stubbornness simply means that you have the kind of tenacity to keep a diet going even when you've plateau'd. You also like routine, so planning your week's menus and shopping accordingly can save you masses of calories.
Is it because I'm a Taurus? Taurus is a sign that loves sensual pleasures, but being the gourmet of the zodiac isn't good for the waistline. Nor does the fact that you like the comfort of feeling full. Soup is your very best friend. Pints of it will work miracles (without cream, silly)
Gemini May 22-June 21
Are the stars on your figure's side? Geminis live on nervous energy and prefer fresh, simple food to gourmet blowouts, which helps to keep a trim waistline. Maybe it's because you're so easily distracted that you often find something more interesting to do than finish a meal.
Most likely to make you fat? If you're portly, could it be that you're a bit too fond of the local Tapas bar? Geminis love meals that comprise of lots of little dishes but you need to be careful with your choices. Go in search of a Bento Box instead.
Eat right: Eat little and often. You need frequent feeding to keep you going. It's not just the boredom factor that puts you off a banquet, it's the way big meals bloat you out. Finger foods and canapes offer the kind of variety you find fascinating, but don't forget that food eaten standing up still counts.
Is it because I'm a Gemini? You get bored of diets and revert to your bad old ways before you can say ennui. And you're an incorrigible snacker. Are crudite's the answer?