THAT old saying "a moment on the lips, a lifetime on the hips" turns out to be absolutely true. Research proves that fructose - a cheap yet powerful sweetener which is added to so much of our food - makes us put on fat round our waists and many experts consider it is the biggest driver of diabetes and obesity.
Those who defend added fructose - especially the food manufacturing industry - say that all calories are equally harmful when we consume too many on a regular basis.
But research undertaken at the Mayo Clinic in America challenges this idea. At the Mayo, experts investigated whether some ingredients were more dangerous than others when it comes to diabetes.
They compared starch, glucose and lactose to added sugars including table sugar (sucrose) and fructose. Fructose does occur naturally in fruit but is usually consumed as an added sweetener.
The Mayo discovered that added fructose damaged our overall metabolisms and our insulin resistance, while other dietary sugars not containing fructose were less harmful.
They found that compared to glucose or starch, fructose leads to fat storage around the stomach, a risk factor in type-2 diabetes.
London cardiologist Dr Aseem Malhotra, the science director of Action on Sugar, agrees. He says that unlike fat and protein, refined sugars offer no nutritional value and, contrary to what the food industry wants you to believe, the body does not require any carbohydrate from added sugar for energy.
So added sugar is a source of completely unnecessary calories.
Sugars are added to the majority of processed foods that we eat every day, such as breakfast cereals and ready meals. Worryingly, many consumers are unaware they are used in such large quantities.
The World Health Organisation was recently advised by scientific experts that added sugar should make up no more than five per cent of our average daily energy intake. That would limit the average man to eight teaspoons a day and the average woman to six, including sugars from fruit juice and honey.
In America, the film Fed Up has caused a storm by labelling sugar as the "new tobacco" and claiming that some food producers are more concerned about profits than public health.
Dr Malhotra says: 'The misleading labelling and health claims on 'low fat' foods that actually have shocking levels of sugar added is a scandal. Worse still, it has created the perfect storm for public health."
There's also a mental effect of overdosing on sugar. Disturbing research on laboratory rats at America's Princeton University showed that high consumption of sugar caused long-lasting changes in the way the brain functions.
Once the sugar supply was stopped, the rats had cravings, went on binges and also developed a taste for alcohol.
This is because sugar releases a chemical called dopamine in the brain. Not only does this produce a temporary high it also affects energy, memory and focus and triggers addiction.
The worst thing is that scientists already know that what sugar does to rats' brains is similar to what happens when they are put on drugs such as heroin or cocaine.
High doses of fructose in rats have also been shown to produce resistance to the hormone leptin. One of the roles of leptin is to suppress the appetite as our body fat increases so if we become resistant to it we become prone to further over-eating and weight gain.
That's a vicious cycle that lies at the heart of the world obesity crisis. The fatter people become, the more their brain makes them want to eat.
The brilliant American expert Dr Robert Lustig, of the Food and Behaviour Research Organisation, has discovered that for every extra 150 calories of sugar consumed, the prevalence of diabetes rises by one per cent.
How do we cut down on the sugar we consume? Lots of people claim it can be done by making a conscious effort and using willpower. For example, eating only home-cooked food - instead of cooking a ready-made meal from the supermarket, cook a fresh one because at least that way you'll know what's in it.
However, we all know that using willpower's easier said than done. If the solution were that easy there wouldn't be an obesity crisis. The most effective way to change your lifestyle and your eating habits on a lasting basis is to use the power of your unconscious mind.
Food marketing experts use unconscious persuasion all the time in advertising and branding to make you buy their products. So the answer is to recruit your unconscious on to the side of the angels so that healthy choices become instinctive and natural.