I was travelling home from work when Michael Pollan's name was announced on the BBC Radio 4 Food Programme by presenter Sheila Dillon. Michael, who is the author of In Defence of Food (Allen Lane £16.99), began the interview as he begins his book: "Eat food. Not too much. Mostly plants." These simple words go to the heart of his book and his food philosophy, which affirms the joy of eating foods our great-grandmothers would recognise, rather than the edible food-like-substances that come packaged bearing health claims.

He believes that real food is the stuff you can't pin a label on. He argues that there was a time when food was all you could eat, but today thousands of other edible food-like substances that come in packages elaborately festooned with health claims are flooding the supermarkets He went on to say that a health claim on a food product is a strong indication that it's not really food.

The programme proved so riveting that on arriving home I remained in the car with the radio still switched on, so that I didn't miss a second of what he had to say.

Michael was in conversation with the Food Agency's chief scientist Andrew Wadge, who didn't disagree with his philosophy exactly, but did take issue with his view that we should junk science, as it helps us understand what constitutes a healthy diet and the wider sociological and cultural issues that influence our choices.

One of Michael's main arguments is that real food is fast disappearing from the marketplace to be replaced by nutrients, and that plain, old-fashioned eating is being taken over by our obsession with nutrition, which is, paradoxically, ruining our health not to mention our meals.

He argues that most of the nutritional advice we have received in the last half century, most particularly the advice to replace the fats in our diets with carbohydrates, has actually made us less healthy and considerably fatter. He says that the very fact that anyone should need to write a book advising people to "eat food" could be taken as a measure of our alienation and confusion about the topic.

One of the aims of his book is to show the limitations of a strictly scientific understanding of something as richly complex and multifaceted as food.

He reminded listeners that we are inclined to forget that, historically, people have eaten for a great many reasons other than biological necessity, as food is also about pleasure, community, family, spirituality and our relationship with the natural world. Food is far more than the sum of its nutrients; it is also more than snacking on the hour every hour. But do the people who eat at their desks, their cars or in the street - grabbing food when they can - know that?

This was the point at which I really began to warm to this man. Friends sometimes laugh at me when they learn that I will happily spend an hour in the kitchen peeling potatoes, chopping meat and paring vegetables to create a full meal rather than pop something ready-cooked into the microwave or snack on the way home. They also laugh when I refer to ready-made foods as plastic meals and refuse to eat them.

Oh I did once. Several years ago I was asked to taste-test three packs of a similar meal prepared by different food manufactures and write up my findings. I remember those meals well. First, the dish itself bore little or no resemblance to the photograph on the lid; secondly, a frozen meal for one was never enough; thirdly, everything seemed to taste the same. Then there were the packs that boasted they were fat-free, but failed to declare they were high in carbohydrates, salt and sugar.

I was particularly concerned about the amount of processing these meals had been subjected to and always felt that on tasting them I was eating 'dead' food, as it had been cooked then frozen, held frozen for some considerable time, then thawed and cooked again. What does this over-processing do to those fragile vitamins that are so important?

It has always seemed common sense to me to follow my mother's example, which was (when possible) to bring a pot of salted water to the boil while she was out in the garden harvesting the vegetable that was to go into it. Obviously, such cooking methods are only possible if you have a garden or allotment - but by buying freshly harvested food from the producer, as you can at a farmers' market, vegetables can be enjoyed while fresh.

As Michael says, you don't need a label telling you a fresh cauliflower is good for you - you just know it is. And all that preparation I do to ensure I only eat real food, which sometimes amuses my friends, is in fact good for my heath. Michael points out that a recent obesity study correlated the rise in the average weight of Americans to the decline in the 'time-cost' eating. The survey concluded that the widespread availability of cheap convenience foods could explain most of the 12lb increase in weight of the average American since the early 1960s.

Condensing what Michael said during a half-hour radio interview and wrote in a 228-page book is difficult. My reason for bringing In Defence of Food to your attention however, is simple. Here is a man who is trying to persuade us to do all the things I am convinced are important- cook raw ingredients, sit down with others and turn a meal into a social occasion, and enjoy food for food's sake and stop treating it as a medicine.

The fact that he's trying to persuade us to eat nothing that our great-grandmothers wouldn't recognise as food does not mean he expects us to sit down to gargantuan Victorian meals. Rather, he urges us to think twice about processed foods such as Turkey Twizzlers and chemical-laden foods that come with extravagant health claims. A varied diet of freshly prepared foods will give us all the nutrients we need.