so much for Mary Poppins. All those spoonfuls of sugar are not only making us fat, they're contributing to arguably the biggest health threat facing humanity: diabetes, caused by soaring levels of obesity. Eating too much sugar can also make us tired, irritable, anxious, spotty and aggressive, and lead to insomnia.

Why do we eat so much sugar?

You shouldn't feel guilty about enjoying sugary foods. Human beings are designed to like sweet things – a clever physiological trick to save us from poisonous plants and berries, which usually have a bitter taste.

Before the agricultural revolution, however, the only sugar we could get in our diet occurred naturally. Starchy foods such as rice, wheat, corn and potatoes – and then bread, noodles and pasta – soon became our principal source of energy. Then someone hit on the idea of processing raw sugar into the refined white stuff you find in most kitchen cupboards – and adding liberal helpings of it to almost every packaged and processed food on our supermarket shelves.

Why is sugar so dangerous?

The West is rushing headlong into a diabetes crisis fuelled by increasing obesity. Both conditions are linked to the intake of too much sugar and
refined carbohydrates. When you pump your body full of sweet things, blood-sugar levels rocket and the body releases insulin in order to remove this excess of sugar from the bloodstream. Where does it put this extracted sugar? On your hips, tummy and bum, in the shape of fat.

Patrick Holford is the author of a new book called How to Quit Without Feeling S**t which treats the issue of sugar addiction as seriously as heroin, alcohol and nicotine. "The root of most of today's killer diseases is actually blood-sugar problems," he says. "So the goal becomes, how do you keep your blood sugar even?"

Regulating sugar intake

There are two main ways to balance blood sugar. The first is to avoid carbohydrates and follow a regime similar to the Atkins Diet, eating a high-protein diet. The second way is to eat a diet that has a low 'glycaemic load' (GL). The glycaemic index tells us how quickly the sugar from certain foods is released into the bloodstream. What it doesn't tell you is how much of that food is sugar. "Atkins limited the amount of carbs, but didn't pay so much attention to the GI," says Holford. "The GI diet limits the fast-releasing GI sugars but doesn't pay enough attention to the quantity eaten."

The obvious solution if you really want to pull your body back from the brink of sugar dependency would be to limit foods that are high in sugar aggressively.

How to quit

The tricky bit. The act of coming off sugar has been likened to going cold turkey on a heroin habit. This seems fairly extreme, but even those of you who don't add three spoonfuls of sugar to your tea every morning are probably overloading on sugar with cereals and fruits. "It takes between two and five days to come out of withdrawal from sugar," says Holford. "We've done work in schools where children are sugar-addicted. They feel flat lacking in energy for a couple of days after removing sugar. But within a week most people begin to experience more energy and more mental clarity."

Beat the sweets:

Tips for quitting

1 Make a low-sugar meal plan. Swap breakfast cereal for oats and try adding low-GL cherries or berries as a sweetener.

2 Eat little and often. This means three meals and two snacks, so have something on hand mid-morning – a handful of almonds should do the trick.

3 Up your intake of Vitamin C. One study showed that a very high intake of Vitamin C reduces blood-sugar levels and lowers the damaging effects of sugar.

4 Use sugar replacements. Work out the times of day you eat something sweet and replace it with something less sugary. For example: a punnet of strawberries has the same effect on your blood-sugar levels as 10 raisins, or one date. Xylose, the sugar in berries, is available in supermarkets as xylitol. You can add this to hot drinks or porridge and bake with it. Manuka honey is a great replacement for refined sugars.

5 Stay off the caffeine. Sorry: you might have decided coffee was to be your crutch while you kicked sweets, but caffeine also disrupts blood-sugar balance. Antioxidants in green tea will help repair any damage done by yo-yoing blood-sugar levels.

6 Get some help. Once you've balanced your blood sugar, you need to make sure insulin is working as it should. Cinnamon supplements will help with this. Tryptophan can help reduce sugar cravings (take 200mg a day) and tyrosine will help you deal with the low moods and flatness in the initial stages (take 500mg twice a day, but none too late in the day to avoid disrupting sleep).