What are healthy diets - the criteria

They cannot be more different. Some purportedly healthy diets emphasize raw foods, some emphasize cooked foods. Some advise to avoid salt, some say salt is healthy.

Some diet plans minimize protein and fats, some encourage eating lots of protein and fats while avoiding carbohydrates as much as possible. And so on.

Personally, I have tried a few of these diet plans and have also changed my mind about them. When I was first introduced in 1985 to the subject of natural health and healthy eating, I was much attracted to various diet plans based on raw foods.

I found the arguments - about vitamins, enzymes, "living foods" etc - convincing and I stubbornly adhered to a raw foods diet even after I developed problems like asthma and a persistent skin rash.

Then I discovered macrobiotics and thought it made a lot more sense, particularly the idea that we should adapt our diets to our body conditions and the environment we live in.

Meanwhile, I continued to view vegetarianism as the ideal. For many years, I believed it was the healthiest among healthy diets, even though I was only briefly vegetarian for about six months.

It was only more recently, around 2004, that I became convinced that vegetarianism is not the ideal and that certain animal products - such as saturated fat and cholesterol - are, in fact, good for health. This is thanks to the Western Price Foundation, which advocates following traditional diets.

In this article, I would like to share with you how I evaluate different diet plans and philosophies, to distinguish the truly healthy diets from diet fads and possibly misguided ideas.

1. Healthy diets must be natural I

This means, fir

stly, that the diet plan must not require you to take any man-made poducts such as, for example, slimming pills. I apply this criteria even when the product may be based on natural ingredients, for example, slimming pills containing only natural herbs.

Another example would be the hCG Diet, which requires followers to take human chorionic gonadotropin, or hCG, a hormone extracted from the urine of pregnant women. The hormorne may be natural. But the method of extraction is not. Nor is it natural to consume such a hormone.

Some people might argue, then, that cooking is not natural. I put it this way... a healthy way of eating should not require any form of technology that is not widely available. For it then means that people without access to such technology can eat in a healthy manner. To me, this is unacceptable.

Cooking is, to me, natural in the sense that even primitive people are able to cook. Same with fermentation, pickling and other natural forms of food processing.

However, I consider fruit and vegetable juicing to be "unnatural" because it requires the help of a food processor or juicing machine, which in turn requires electricity. Sure you can produce juices naturally, by squeezing with your hands or chewing and spitting out the pulp. But you cannot produce the large amounts of juices that people who follow such diet plans drink every day.

2. Healthy diets must be time-tested

This means healthy diets are traditional diets that have supported generation after generation of people in communities for hundreds or thousands of years.

If a particular way of eating had been around only for a few years or a few decades, and if it had not been followed by parents, children, grand children and many generations of people, we cannot say for sure that such a diet plan can support life in the long term.

In India, for example, there are communities of people who are born vegetarians and their parents, grandparents and possibly older ancestors had been vegetarian. To me, this means that a vegetarian diet is sustainable and most probably healthy.

I cannot say the same, however, about a vegan or pure vegetarian diet. It may be true that there have been people who followed a vegan diet ever since hundreds or thousands of years ago. But these were individuals. As far as I am aware, there has never been entire communities of vegans who observe the same diet plan for many generations.

Here, I should mention that many modern "foods", including genetically modified foods and hydroponic vegetables, have likewise not been time-tested. They are claimed to be safe or even healthy yet the long-term health effects of eating such foods are unknown.

3. Healthy diets are not the ideas of individuals

Another sign of arrogance is when one individual - whether a doctor or natural health advocate - develops his or her own healthy diet plans.

Popular examples include the Atkins Diet developed by Dr Robert Atkins, the South Beach Diet developed by cardiologist Arthur Agatston and dietician Marie Almon, and the blood type diet developed by naturopathic physician Peter d'Adamo.

Health and diet is a very complex subject and I do not believe that any one or two person, no matter how brilliant or learned, can come up with healthy diets that suit large sectors of the population. Because individuals are ultimately limited in their knowledge and understanding.

To me, healthy diets should be based on major schools of thought, rather than individual ideas. By "schools of thought" I mean, for example, nutritional science - although I disagree with its teachings but it is a "school of thought". Other schools of thought include Ayurveda or Traditional Chinese Medicine.

Here, it is important to differentiate between individuals who interpret and explain existing diet philosophies, and those who cook up their own theories.

Macrobiotics, for example, can be said to be started by certain individuals. Its history could be traced to George Ohsawa, who applied the term "macrobiotics" to apply to his teachings, or earlier to his teacher, Sagen Ishizuka.

But these individuals, as well as their successors like Michio Kushi, merely explain and interpret traditional concepts based on the orieintal principles of yin and yang. They did not concoct their own diet plans - and they certainly did not (arrogantly) name such diets after themselves.

Likewise, people like Dr Mary Enig and Sally Fallon of the Weston Price Foundation advocate certain ideas about healthy eating based on the observations of Dr Weston Price, a dentist who travelled around the world to study how diet affected people's health. Dr Weston Price did not develop his own diet plan, nor did Mary Enig and Sally Fallon.

4. Healthy diets must be adaptive

Another feature of healthy diets is that they must be adaptive, recognising that different people have different needs. Any diet plan that recommends the same foods, or the same way of eating, for everyone, will not meet the grade.

For example, diet plans based on raw foods recommend that everyone eats plenty of raw vegetables and fruits, or raw sprouts, as their main food.

In contrast, the teachings of macrobiotics say that people who live in hot tropical climates may eat more raw vegetables and fruits, and those in colder climates might do so during summer. To me, this makes a lot more sense than saying that everyone should eat in the same way.