HEART attacks, strokes, cancer, asthma, allergies, migraines, colitis, infertility and type-2 diabetes:

given that these obesity and diet-related conditions are on the rise all over the developed world, it is little wonder that our obsession with food and healthy eating is increasing, too.

That has led to a whole lexicon of dietary terms that are often used without much accompanying explanation. So, how do you tell your glycaemic index from your glycaemic load?

HIGH PROTEIN:

This refers to the best-known diet of them all, the Atkins diet. Dr Robert Atkins died in 2003, but by that time the diet he invented was going through a sharp decline in popularity. On a promise that replacing carbohydrates with protein would result in weight loss, it swept the developed world, was adopted by celebrities and caused a fall in demand for bread, potatoes and pasta. However, its effects were often short-term and nutritionists began to warn of the dangers of an unbalanced diet.

GI:

Enter the glycaemic index (GI), the new buzz phrase for those who want to lose weight as part of a healthconscious diet. This is a scoring system for different foods based on their potential to raise blood glucose levels. Glucose is rated at 100 and everything else is relative to that: an apple, for example, is 38.

The GI applies only to foods that contain carbohydrate; it is not relevant to high-protein and high-fat foods including meat, eggs, nuts and cheese. It is very difficult to measure the GI of fruit and vegetables, which have a low carbohydrate content, because it requires 50 grams of carbohydrate to be consumed.

The crudeness of the system is illustrated by the fact that carrots and chocolate are rated equally.

Chocolate and carrots have the same GI because they release sugar at the same rate, but you would have to eat three whole carrots to get the same amount of carbohydrates as three squares of chocolate.

GL:

Unravelling that sort of anomaly led to the concept of the glycaemic load (GL). It is a refinement of GI which multiplies the GI value by the total carbohydrate content of the serving. Thus some foods that are excluded on GI diets - such as carrots and watermelon - can be part of a GL diet. While it sets a daily GL limit, it works on the principle that people can avoid hunger and cravings if they control their blood sugar, and once blood sugar control is attained they gain energy and lose weight. It advocates eating protein-rich foods along with lowcarbohydrate ones.

II: INSULIN INDEX:

Important for diabetics, the insulin index measures a person's insulin response after a meal, as indicated by blood tests. Unlike the glycaemic index, which measures the body's response only to certain carbohydrates, it takes into account the fact that a person may have eaten foods containing fat, which also stimulate an insulin response. These include foods that are generally regarded as healthy, such as fish and yoghurt.

GGE: GLYCAEMIC GLUCOSE EQUIVALENTS:

This term is similar to "net carbohydrate". It is the portion of available carbohydrate that elicits a blood glucose response. It can be a useful guide to people wishing to reduce their intake of sugars and fast carbohydrates, in favour of the consumption of non-digestible carbohydrates such as fibre, but the GL is probably a simpler way of doing this.

SOME terms with a scientific basis are used widely in marketing the health benefits of certain foods, although it may not be completely clear to the consumer just exactly how they improve health. Food labelling is strictly governed by law and the claims made must not be misleading. The Food Standards Agency offers the following guidance:

PROBIOTICS:

Nowwidely available and marketed as health or functional foods, whereby they are ingested for their purported positive advantages in the gut (digestive tract). They range from fermented milk to milk containing certain bacterial strains.

Dietary modulations of the human gut microflora may be of benefit to health; however, more data on the survival of probiotics in the human gut - and therefore their efficacy - is being sought.

NATURAL:

Means essentially that the ingredients in the product are produced by nature - not the work of man or interfered with by man. It has been deemed misleading to use the term "natural" to describe foods or ingredients that employ chemicals to change their composition or comprise the products of new technologies, including additives and flavourings that are produced by the chemical industry or extracted by chemical process.

LIGHT OR LITE:

There are no rules to say howmuch less fat or how many fewer calories "light" foods must contain.

The Food Standards Agency recommends that consumers take a close look at the nutrition panel and compare the information per 100g.

It says: "You may be surprised at how little difference there is between foods that carry claims and those that don't - a 'light' or 'lite'version of one brand of crisps may contain the same amount of fat or calories as the standard version of another brand.

Tempting biscuits and chocolate bars that claim to be light on fat can contain almost as many calories as the standard versions."

LEAN:

The term lean is used by manufacturers to give the impression that a product contains less fat than the "standard" product. However, a survey of types of mince described as "standard", "lean" and "extra/super lean" in 2004 showed extensive overlap in the fat content.

LOW CALORIE:

Afood can't claim to be "reduced calorie" unless it is much lower in calories than the usual version. Low fat must be no more than 3g per 100g. Low sugar must be no more than 5g per 100g and low salt must be no more than 40mg sodium per 100g.

Patrick Holford, a nutritionist who founded the Institute of Optimum Nutrition 20 years ago, believes that with understanding of GL, diet and nutrition experts have "found the gold" on the long quest for the perfect eating formula.

He says: "It began with the discovery of the calorie and the idea that fat will contain more calories. That led to the low-fat diet.

Then the idea that weight loss depends on blood sugar control led to the high-protein diet. Then the realisation that not all carbohydrates are the same led to the glycaemic index as a way of controlling blood sugar.

"Nowwith the glycaemic load we understand the importance of quality times quantity.

"I don't foresee a further step. The diet is doable in the long term, people lose weight and it promotes health."

The Holford Low-GL Diet, Patrick Holford, Piatkus GBP7.99.

Antony Worrall Thompson's GI Diet, GBP12.99.

The Low GI Diet Revolution:

The Definitive Science-Based Weight Loss Plan, Jennie BrandMiller, Kaye Foster-Powell and Joanna McMillan-Price The Good Carb Cookbook:

Secrets of Eating Low on the Glycemic Index, Sandra Woodruff The GI Diet: The Easy, Healthy Way to Permanent Weight Loss, Rick Gallop Low GI Cookbook: Over 80 Delicious Recipes to Help You Lose Weight and Gain Health, Louise Blair Food Standards Agency:

www. food. gov. uk www. eatwell. gov. uk/foodlabels/ labellingterms Patrick Holford:

www. patrickholford. com