By JILL FULLERTON-SMITH

Last updated at 08:30 19 December 2006

Are we what we eat? It's a question we put to the test with the help of the UK's leading scientists, setting up a number of experiments using the latest research techniques.

To assess the effectiveness - or not - of detoxing, we took ten female volunteers between the ages of 19 and 33, who had been partying hard at a rock festival, and whisked them away to country cottages in Devon. Five were put on a detox regime designed by a group of eminent dieticians, including Nigel Denby from Hammersmith and Queen Charlotte's Hospitals in London. The other five acted as "controls" and followed a normal, healthy diet.

The detox diet rules included: no processed food - everything to be made from scratch; no added salt or sugar; no tea or coffee; no wheat, red meat, dairy produce, alcohol, squash or fizzy drinks; and organic produce wherever possible.

Two toxicology experts from Imperial College,

London, and nutritionist Professor Gary Frost from the University of Surrey checked over what we were feeding both groups.

We then investigated kidney function by measuring the level of creatine in the women's urine. Creatine is produced by the breakdown of a chemical in your muscles: a healthy kidney will allow a fairly constant amount in your urine.

We also checked the women's liver function and gave all of them a blood test to find the concentrations of aluminium - a metal commonly used in takeaway cartons and kitchen foil.

Finally, we measured levels of key antioxidants (vitamin C and vitamin E).

So did the detox regime cleanse our testers' bodies to a superior degree?

No. Livers and kidneys were functioning just as well in both groups, while both also had similar concentrations of antioxidant vitamins.

There is no evidence to show that starving ourselves rids us of the toxins that we like to think are clogging our bodies: our liver and kidneys are the perfect detox machines already. Most people lose weight on a detox diet simply because they have reduced calorie intake.

To help "cleanse" your body, experts advise cutting down on high-fat, high sugar foods and topping up with filling fruit and veg. To reduce the amount of detoxing the liver must do, avoid alcohol and caffeine.

Is there any easy way to lose weight?

Science shows that a slow and methodical approach to weight loss, with calorie control and exercise, is the best way to lose weight and keep it off. So nothing new there.

But are there any additional steps you can take to help you slim down more easily? The latest research indicates there are.

• CALCIUM - in particular, low-fat dairy products - seems to help the body burn fat more efficiently. In 2003, Professor Michael Zemel of the University of Tennessee carried out a study in which half the volunteers consumed three small cartons of low-fat yoghurt each day as part of a calorie-controlled diet. All the volunteers had exactly the same number of calories overall, but those who ate the calcium-rich yoghurt managed to lose 20 per cent more body fat.

There seem to be two sides to the flab-busting effect of calcium. First, and most surprisingly, calcium has been shown to cling to the fat inside our intestines. Together, calcium and fat form a substance very similar to soap that can't be absorbed across the wall of the intestine, so it passes out of the body. The more calcium you have in your diet, the more fat will be excreted.

The second effect of dietary calcium is the more complex role it plays in metabolism. As a rule, calorie controlled diets tend, unfortunately, to reduce the rate at which your body burns energy and slow down weight loss. Calcium, however, seems to offset this effect - boosting metabolism and helping to speed weight loss.

You should aim for around 700mg of calcium a day: 300ml of semi-skimmed milk contains 360mg calcium; 1 canned sardine with bones, 115mg; 2 large tablespoons shelled prawns, 90 mg; 1 large orange, 70mg.

• SOUP can help you slim. On any weight loss programme, you want to keep your calorie intake down and feel full for as long as possible. To do this successfully, experts recommend eating low-calorie soup. Working with scientists at the University of Nottingham, we recruited 20 volunteers and prepared two versions of the same meal - chargrilled chicken and vegetables with a bottle of still water.

In one version, all the ingredients were presented solid on a plate and the bottle of water drunk. In the other version of the meal, the same ingredients were mixed with the water and blended to make a soup. Volunteers completed a questionnaire every 45 minutes for three hours - to let us know how full they felt.

Everyone who ate the soup meal felt fuller for longer, while MRI scans of the volunteers' stomachs showed the soup did indeed fill the stomach for significantly longer.

Do party foods make children hyperactive?

Most parents assume that children plus sugary foods equals raucous and uncontrollable behaviour - the dreaded sugar "high". But although a child can consume the equivalent of 20 to 30 teaspoonfuls of sugar at a typical children's party, the "high" is a myth.

The body doesn't use up all its sugar all at once: if there's extra glucose available, it squirrels some away to have later. True, blood-glucose levels will rise slightly and temporarily - but will soon be back to normal. And even if the blood-glucose level is slightly raised, your brain doesn't start working faster.

Brain cells have only one speed. So if kids consume lots of cakes at a party, they may

feel full, even sick, but it won't make them hyperactive.

To prove the science, we held two carefully orchestrated children's parties. The first was a high-energy romp with an entertainer and music - but hardly any sugar. When the parents dropped off their children, they saw plates of sugar-rich goodies that they assumed were for the party but were quickly hidden once all the parents had gone.

Two weeks later, the same children came to our second party - a calmer affair with storytellers and quiet activities. This time, there was an array of sugar-packed foods presented to look like a healthy lunch.

After the first party, all the children were indeed hyped up, even badly behaved - despite the fact they had eaten little or no sugar. After the second party, they were much quieter - even though they'd had lots of sugary foods. However, the parents believed the children's behaviour after the first party had been due entirely to sugar.

In another experiment, we found that restricting children's access to certain foods only makes them more popular. So allow all foods - but teach children that some are healthier than others. They need to learn that cakes, biscuits, sweets and sugary drinks should be enjoyed only occasionally.

Will drinking more water help your skin?

We've all been told that drinking more water is essential for good health and can lead to better looking skin - but is this myth or fact? According to a plethora of scientific evidence, you really don't necessarily need two litres of water every day.

Research shows that your body will let you know when to take some more fluid on board long before you become dehydrated - and caffeinated and alcoholic drink, as well as the water that occurs naturally in food, all contribute to your total intake.

Can drinking more water make your skin look and feel more rejuvenated, though? The science behind your body's water regulation system would suggest not. You can't force extra water into skin cells to pump them up, for example. To find out the truth and convince the unbelievers, we worked with two sisters, Susie and Alice, who usually stick rigidly to two litres of water a day. Both girls lead busy lives, working and socialising.

We asked Susie to abstain from her water habit for five days. During those five days, we then made sure both sisters ate and drank the same - apart from the extra 2 litres of water Alice drank each day. We used a "triplesense" sensor to measure the women's skin moisture content. Using a sophisticated microscope, we also looked at their skin close up. And we measured the colour of the women's urine to gauge their levels of hydration.

Tests at the start and end of the five days showed that neither sister was dehydrated. Both women's skin was in great condition in both tests. The only difference was that Alice had to splash out on an expensive two litre bottle of mineral water every day - and she probably spent more time in the bathroom.

Can healthy eating beat PMS?

The big news in Pre-Menstrual Syndrome research at the moment concerns a clever combination of calcium and vitamin D.

Calcium is vital not just for building healthy teeth and bones, but also in a huge number of other vital body processes.

Vitamin D fulfils many roles, too - but most importantly, it helps your body absorb calcium from food. Researchers have shown that calcium and vitamin D supplements can reduce the severity of PMS symptoms by half in just under 50 per cent of sufferers.

With the help of Nigel Denby, senior dietician at Hammersmith Hospital and Queen Charlotte's Menopause and Women's Health Clinic, in London, we devised the "Double D" anti-PMS diet.

The first D is for dairy foods - a good source of calcium; the second for vitamin D. And if the calcium and vitamin D combination works with supplements, there seems no reason why it won't work if the nutrients come from your food.

If you suffer from PMS, the Double D diet is well worth a try. It can be used as an add-on to what you normally eat, with extra calcium from additional milk, yoghurt and cheese, and extra vitamin D from oily fish, margarine, eggs and cereal.

Every day, you should consume 1,500 mg of calcium and 20 micrograms of vitamin D from food. Sources of calcium include: 300ml semi-skimmed milk, 360mg calcium; 300ml semiskimmed milk with 50g of dried skimmed milk powder added, 1,000mg; 150g pot low fat yoghurt, 285mg; 75g Cheddar cheese, 630mg; 75g Parmesan, 900mg; 75g Edam, 578mg.

Sources of vitamin D include: 100g grilled herring, 25mcg vitamin D; 100g baked kipper, 25 mcg; 100g smoked mackerel, 8 mcg; 100g canned salmon, 12.5 mcg; 100g sardines in tomato sauce, 7.5 mcg; 100g tuna in oil (drained), 5.8mcg; 50g low-fat spread, 2mcg; large boiled egg, 1.2 mcg.

Is there a diet that cuts blood pressure?

Current medical wisdom suggests that if you lower your cholesterol and your blood pressure, you will significantly reduce your chance of suffering from heart disease and stroke - two of the developed world's biggest killers.

As a result, millions of people now take drugs called statins that reduce levels of "bad" cholesterol by up to a third.

We wanted to see if cholesterol and blood pressure could be lowered through diet alone. Some scientists say you just have to say no to junk food, alcohol and sugary snacks, and eat the same basic diet as our ancestors did.

Archaeological research tells us that the human diet in 180,000BC consisted mostly of vegetables, fruits, nuts and seeds, with a little lean meat and fish. In other words, a high-fibre diet rich in plants and unsaturated fat and low in saturated fats.

We asked a group of junk food-loving volunteers to try out the "evo" (evolutionary) diet for 10 days. Blood and urine samples were taken, as well as blood pressure readings. After 10 days, our volunteers' blood cholesterol had reduced by nearly a quarter and their blood pressure was down by about 10 per cent.

Eat like your ancestors

Aim to eat a rainbow of fruits and vegetables, and at least five portions a day.

Reduce your intake of saturated fat: cut down on fatty meat, meat products such as sausages, hard cheese and full-fat dairy products. Replace with oily fish, lean meat, nuts and low-fat dairy products.

• Choose oils rich in monounsaturated fats such as olive oil and rapeseed oil.

• Choose unrefined carbohydrates such as wholemeal breads and pasta, brown rice and wholegrain cereals.

• Watch your salt intake. Avoid adding salt and choose herbs, lemon juice and garlic for flavouring. Avoid heavily salted food such as bacon, cheese and crisps.

Extracted from The Truth About Food by Jill Fullerton-Smith, to published by Bloomsbury on January 2 at

£15.99, in association with the BBC. Copyright: Jill Fullerton-Smith 2007. To order a copy at £14.40 (p&p free), call 0870 161 0870. A six-part BBC2 series of the same name begins on January 11.