Advice on fighting ageing has become as traditional in January as the sales – yet the various recommended strategies can demand far too much effort for few convincing returns. So here's some of the science on anti-ageing – along with four tried and tested ways to look and feel younger than you are.

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The strong stay young

"Challenging exercise is the closest thing to an anti-ageing pill for everyone, not just for athletes and health nuts," say the celebrity trainers Tim Bean and Anne Lang, authors of Turn Back Your Age Clock (Hamlyn, £12.99), to be published this month.

The emphasis here is on "challenging" – a stroll in the park won't do. You have to work your muscles to the limit, exercising harder and faster to make your body perspire and your heart race, within an aerobic training zone that's between 60 and 80 per cent of your maximum heart rate (your age subtracted from 220), according to Bean and Lang.

High-intensity aerobic exercise "increases the body's need for oxygen and therefore improves the capability of heart, lungs and blood vessels to supply oxygen to the muscles," they say. And studies confirm the benefits of challenging your body with regular aerobic exercise to prevent ageing-related diseases.

There's no need to join a gym or pay a trainer. All you need is a pair of well-fitting training shoes, and women should wear a support bra, say Bean and Lang.

Four top tips for aerobic exercise are:

Brisk power walking: By the time you have warmed up and got into your stride, do the "talk test" – you should be breathing harder and starting to perspire and be unable to hold a chatty conversation, although not so breathless that you can't utter a few sentences.

Jogging: Start slowly until your body has lost its cumbersome slowness and begins to feel fluid and streamlined. Then set yourself a distance and a time, and work at beating your personal best in each workout.

Skipping: This most inexpensive and portable cardiovascular workout is a wonderfully intense high calorie-burner for those who have built up a good fitness level.

Cycling: This is especially good for the elderly or overweight. To burn calories, you need to increase your intensity and distance. Adjust the height of the seat so that the leg at the bottom of the down-stroke is almost but not quite completely extended.

Bean and Lang promise that you will "look and feel 20 years younger in only eight weeks" – but to get there, you'll need to alternate 50 minutes of aerobic exercise with an anti-ageing workout made up of rejuvenator circuit exercises that "hit on ageing hot spot areas".

The favourite exercise for celebrity clients who are preparing to appear on the red carpet is "the turtle": repeat it 20 times three times a week for a defined and athletic appearance to back, buttock and shoulders.

Here's how it's done:

1. Lie relaxed, prone on your front, on the floor with arms extended in front of you and legs together.

2. Inhale and raise your head, arms and legs just up off the floor. Sweep the arms around in a wide arc until your hands reach your sides. Squeeze your buttocks and thighs.

3. Exhale as you return to the original position, then repeat the movement, keeping your arms up off the floor at all times until the exercise is finished.

Save your skin

Regular exercise, a balanced diet, and obsessive use of sunscreens and an adequate moisturiser should keep your skin glowing, whatever your age.

If you are going to invest serious money in your largest organ, dermal fillers are the only method that is scientifically proven to smooth crepey or damaged skin and fill out wrinkles.

The latest filler, Restylane Vital Light, launched in the UK this week, is a baby version of this successful range. Consisting of a less concentrated hyaluronic acid gel, Vital Light has been specially designed for use in those more sensitive, difficult-to-treat skin areas that can add years to your appearance: crow's feet, the neck and décolletage and the back of the hands.

By injecting the gel underneath the dermis, the filler is able to stimulate natural collagen production and replenish supplies of naturally occurring hyaluronic acid, thereby boosting skin elasticity and firming up these delicate skin areas.

"It's very satisfying finally to have a treatment option for these difficult areas which can be ageing even in women in their thirties," says Dr Tracy Mountford, medical director of the Cosmetic Skin Clinic and a member of the British Association of Cosmetic Doctors. "The treated skin looks younger, more dewy and hydrated, and feels smoother and firmer." Vital Light costs £500 to £600 for an initial treatment, which will require an upgrade every six to nine months.

Fix your posture

Banishing back pain could well be your single most effective anti-ageing strategy in 2009. And the best long-term strategy to beat back pain, according to a major study published in the British Medical Journal in December, is a course of just six lessons in the Alexander Technique.

After a year, it is more effective than painkillers or massage because "it equips patients with life skills they are more likely to be able to use beyond the intervention period", according to lead researcher Sandra Hollinghurst, a health economist at Bristol University.

With AT now set to be more widely available in general practice and for hospital out-patients, Alexander teachers are quick to point out that their lessons bring many anti-ageing benefits other than freedom from pain. Most commonly, people experience improved mobility, alertness, confidence, general health and inner calmness, according to a recent survey of Alexander "pupils", carried out by Stat (the Society of Teachers of Alexander Technique).

"The key to a youthful appearance is getting a better relationship between your head, your neck and your back," says the AT teacher Anthony Kingsley ( www.alexanderstudio.co.uk ). "By freeing up your neck muscles, you develop poise, vitality, flexibility and twinkling eyes – all more important factors in looking young than what you wear or how many wrinkles you've got," says Kingsley. He gave regular AT lessons to the TV presenter Lisa Snowdon on her way to the final of the most recent series of Strictly Come Dancing.

A course of lessons, Kingsley says, lengthens and widens the spine, thereby freeing up the organs. "Too many people spend most of their lives with their lungs, abdomen, liver and kidneys compressed. When you lengthen the back, you free up the lungs so that your whole system is better oxygenated. Your digestion improves, and your body functions better overall."

There's also evidence that AT training teaches us to exercise with more freedom and efficiency, helping to prevent injuries that are caused by people holding themselves too rigidly or putting to much effort into physical activity.

Above all, a more youthful posture helps to create a sense of joie de vivre, according to AT enthusiasts, including George Bernard Shaw, who started lessons in his late seventies. "With your head uplifted, your eyes are more vital and you're more sprightly whatever your age. Alexander is all about learning good habits and real stress management where mind and body manage life's problems harmoniously," says Kingsley.

You can find an AT teacher on the Stat website at www.stat.org.uk.

Plan what you eat

Many of us will plan a full appointment diary for up to six months ahead but leave food choices to the last minute, warn Bean and Lang. Such people then risk buying "any old thing that looks or smells good – a deli sandwich or a French pastry that will wallop you with as many calories as a full meal but leave you feeling hungry again soon afterwards".

Instead of leaving meal plans until you're hungry and tired, take 10 minutes every three days to follow this process:

1. Decide what you'll eat for the next three days.

2. Base the menu on unprocessed "superfoods": wild game and fish, fresh vegetables and seasonal fruits and seeds, all eaten as close to their natural state as possible.

3. You should plan four main meals a day (breakfast, lunch, high tea and dinner). But you can make your life easier by using the same meal that you have for supper one day for your lunch and tea the next, say Bean and Lang.

4. Do your shopping list and work out your cooking and food preparation times.

5. If you're going to eat out, phone the restaurant ahead to pre-order your meal.

Here are two useful (but controversial) anti-ageing tips:

Bin the vitamins, and save the money. A series of major studies published in November and December last year showed beyond doubt that, while a diet rich in fruit and vegetables is a great way to stay young, taking vitamin supplements has no effect whatsoever.

Low-fat or no-fat diets are ageing. "Full-fat food supports our bones, protects the liver, enhances the immune system, boosts the libido and absorbs omega-3s," says the nutritionist Esther Blum, a member of the American Dietetic Association and author of the American bestseller Secrets of Gorgeous: Hundreds of ways to live well while living it up. The trans fats in processed foods should indeed be avoided, she says. But Blum has persuaded the likes of Sarah Jessica Parker (left) and Sharon Stone to stay youthful by starting the day with an omelette made from egg yolks and cooked in butter – a meal rich in saturated fats.