Fat causes fat?

These days it doesn't take much energy to live. Most people own cars - no need to run to catch a bus. And with in-home entertainment centres why struggle to a football match?

At the same time as our energy output has gone down our energy input has gone up. Food is now cheaper than it has ever been. The average UK family spends less than 10% of its income on food. It’s probably fair to say that most people now can afford to eat whatever they want whenever they want it.

So it should come as no surprise that as a nation we are becoming fatter. And it's not a gradual effect. We are getting fatter at an alarming rate. The figure shows the percentage of the UK population classed as clinically obese has increased from 7% to over 23% in the last 20 years. This is probably the fastest change of any measured human parameter in history. Of course, lack of exercise has a major role to play, but so to has diet.

Government and their nutritionists have not been unaware of this alarming trend and in order to stem the tide have exhorted the population to eat less fat. Weight-for-weight fat packs twice the calories of carbohydrates or protein. And indeed the percentage of our energy intake in the form of fat has, in fact, fallen over the past 20 years. But the drop in fat consumption has done nothing to stop the rise in obesity. The current demonization of fat may in fact be ill-advised. The truth is that there are good fats which we need and bad fats which we should avoid. For more info consult Udo Erasmus.

So if fat intake is not the cause of the obesity crisis what is? We must look elsewhere for an explanation. Many scientists, working at the forefront of human nutrition, now believe that the answer lies in the effect that carbohydrates have on your blood sugar level. This is called the glycemic effect.