by Juliet Kinsman

With new trends appearing all the time, it can be hard to know what's just a crazy fad and what could really work for you. We demystify the diet and fitness theories for 2005

How to eat

The common sense diet

The theory: There looks to be a big move away from fad eating regimes towards a more balanced view of nutrition. After years of craze diets, it's all come back to what granny said in the first place: eat a little of everything, munch in moderation and make sure you exercise.

Expert opinion: When it comes to giving extra pounds the heave-ho, don't cut out the carbs or forbid fat on your forks - just eat healthily, is the crux of Ian Marber's theory in his Food Doctor Diet. He suggests you stick to ten principles to make healthy eating work:

1. Breakfast is important.

2. Eat protein with complex carbohydrate.

3. Stay hydrated (drink up to two litres of water a day).

4. Eat a wide variety of food.

5. Eat little and often.

6. Avoid refined carbohydrates and sugar (white bread, cakes and biscuits).

7. Exercise is essential.

8. Follow the 80:20 rule (there's room for cheating - but only 20 per cent of the time).

9. Make time to eat (sit down and savour your meals, don't eat on the run).

10. Eat fat to lose fat - but it must be the right kind (unsaturated). Eat the right fruit and veg

The theory: Yes, you should eat at least five servings of fruit and veg, but some are much better than others.

Expert opinion: Patrick Holford analysed fruits and vegetables, based on six key health factors, and determined that indeed some have a higher nutritional value than others. 'We tested them with the ORAC rating, glucosinolate content, which is a key phytonutrient in vegetables, zinc, folic acid and vitamin C,' he reveals. 'For fruits we also measured their "glycaemic load", which is the extent to which they raised your blood sugar.'

The winners? 'The best vegetables are tenderstem, which is a cross between broccoli and kale, broccoli, asparagus, curly kale and spinach. The top fruits are berries - strawberries, raspberries, blueberries, followed by oranges and red grapes. Make sure these are staple foods in your diet.'

Gi index

The theory: Being hailed as the new Atkins, this focuses on the speed at which foods are broken down by the body to form glucose, the body's source of energy. High Gi foods break down quickly and lead to cravings. Low Gi foods take longer to break down and leave you feeling fuller for longer. It's these low Gi foods that form the core of the diet.

The expert: 'This is a healthy way of eating, even if you don't want to lose weight, as you only eat enough to fill you up, and it's not full of refined sugars,' says nutritionist Sally Turberville Smith at www.foodandface.co.uk. But there's more to it than just what you eat. 'The most important thing is to have a healthy relationship with food and eat a little of what you want when you want it, stop when you're full, sit down for proper meals, and chew slowly. Even if you eat the perfect Gi foods, if you're stressed out the diet won't work. How you eat is just as important as what you put in your mouth. If you gobble food you miss the signals that you're full, and there is less saliva production, which creates enzymes.'

Boost your vitamin intake

The theory: Many multivitamins contain only 100 per cent of the RDA, but this can be nowhere near enough for high-level health.

The expert: 'If you want to be at optimal health, with the best energy, immune strength and a sharp mind you will benefit from optimum amounts of vitamins and minerals,' says Patrick Holford (New Optimum Nutrition Bible from Piatkus). 'Look for multivitamins that give you at least 25mg of each B vitamin, plus 10mg of zinc and minerals like chromium and selenium. I like Higher Nature's Optimum Nutrition Formula and Solgar's VM2000. I also take 1,000mg of vitamin C every day.'

Top tip: start knitting 'A great way to stop telly snacking or smoking,' says Nicki Waterman. 'And, because it's repetitive and focused, it relieves stress as your pulse rate slows down.'

How to exercise

The Peripheral Heart Action (PHA) workout

The theory: Based on increasing your metabolic rate by elevating the heart rate to an optimum level, Matt Roberts claims that if his comprehensive exercise plans are followed correctly, results will be clearly visible within six weeks. The PHA Workout is by Matt Roberts http://www.personaltrainer.uk.com (#12.99, from Dorling Kindersley).

Expert's opinion: 'The reason it's different is that it allows people to get the most back from their workout,' says Matt. 'People waste about 60 per cent of their time in the gym, and this means that they can achieve twice as much in the same time, or get the same results as they did before in half the time.'

Interval training

The theory: Most people use a continuous form of exercise at the same level and speed for the whole session. By combining high- and low-intensity exercise you can perform longer total periods of high-intensity work, which will improve fitness and help burn more calories as it raises your heart rate. Plus lower intensity periods allow for recovery while the body keeps working.

Expert's opinion: 'It allows you to adapt your routines and keep your body working at progressively greater workloads,' says Kristoph Thompson, a highly qualified personal trainer who swears by this method. (www.kristoph.co.uk)

Core training

The theory: Concerned with developing strength from the inside out, this applies to any exercise which works the deep abdominal muscle, which is often neglected, but is crucial to stabilising the spinal column and pelvic area.

Expert's opinion: 'There's no doubt that core training is crucial as part of every routine but not as important as it's been made out to be in the last few years,' says Matt Roberts. 'As part of an overall workout it's great because it provides a good base to work from. But you shouldn't devote more than your work out time to pure core strength work. In itself, it does not make you lose weight.'

New classes Nicki Waterman recommends taking part in a whole range of activities, such as some of the exercise classes new to our shores. 'I think anything that is fun and that you enjoy is great. In the case of exercise, variety really is the spice of life,' says Nicki. (www.nickiwaterman.com)

Here's a selection of the new classes on offer:

Baby boot camp: Group cardio, where you take your little one with you, and even lets you use the buggy as a prop during the class.

Gyro tonics and now gyro kinesis: This involves series of machine-based moves and looks set to explode. Known as yoga in motion, it's loved by Gwyneth Paltrow.

Yoqua: The latest therapy from the US, basically yoga in a swimming pool.

Top tip: Fitbug If you have an active lifestyle and find it hard to schedule trips to the gym, then hope may still be at hand. Fitbug is a matchbox-sized gadget that tracks your activity levels via your PC and the Web. It measures how far you're walking, and when connected to your computer, it develops a tailor-made health-and-fitness plan based on your personal goals. If you have a busy lifestyle, this helps you make the most of it. Priced #9.95 a month.