From theory to practice. In last month's article we introduced the medical/scientific basis of Barry Sears' concept. This month we will be going into more detail about how the Zone diet is actually made up.

Key balance. The link between proteins and carbohydrates and the introduction of proper amounts and types of fats are essential in order to regulate hormonal and super-hormonal insulin/glucagons and 'good' and 'bad' eicosanoids.

The right proportions. According to Barry Sear's studies it is fundamental that the link between protein and carbohydrate is kept within a range between 0.6-1. The exact figure depends on each individual's metabolism, or rather his insulin response. In theory an ideal figure is 0.75. 

Body mass and protein. Individual protein requirements are not only strictly linked to age and sex but also to weight in terms of body mass, as well as working and sporting activities carried out. How do you calculate it? Barry Sears has identified a protein index that is calculated on each person's lifestyle. The amount of protein needed is achieved by multiplying this index with body mass.

Individual quantities. In theory a person with a sedentary lifestyle needs a protein index of 1.1g (per kg of body mass), whilst a sports enthusiast undertaking intense workouts needs up to 2.3g. For someone with a moderate working life who does sport regularly three times a week the figure hovers around 1.5-1.7g.

In the Zone all day long. The protein requirement affects the distribution of other macro-nutrients (carbohydrates and fats). Proteins are divided up into mini-blocks of 7g each throughout the day, which is the minimum quantity necessary to kick-start the hormonal process. 

Carbohydrates? Wholewheat are best! Since balance should reign at all times in the hormonal cycle a single mini-block of protein should therefore correspond to one of carbohydrates. Bear in mind that the ideal proportion of protein is 0.75-7g and the corresponding amount of carbohydrates is 9g. Wholewheat foods are recommended to avoid overly fast absorption.

'Good' and 'bad' fats. These are also fundamental in a correct diet as essential fatty acids form the basis of eicosanoids. According to Sears though, foods containing arachidonic acid should be avoided as they help develop bad eicosanoids (egg yolks, red meat and innards), and, naturally, saturated fats. Which are good fats then? Polyunsaturated and monounsaturated, such as olive oil, that neither convert into eicosanoids, nor interfere with insulin levels.

The 'block' concept. Based on the above, the Zone diet divides up macronutrients into blocks. These are calculated by splitting up the protein requirement by 7 (this quotient is based on studies carried out on protein by Sears). One block is therefore made up of:  9g of carbohydrates (sugars), 7g of proteins and 3g of fats.

A practical example. Let's suppose you have a body bass of 65k. Multiplying this by a protein index of 1.6g (moderate physical activity) we obtain a protein requirement of 104g. Splitting this up by 7 gives us 15 blocks that could be consumed as follows: 4 at breakfast, 4 at lunch, 2 at tea, 4 at dinner and 1 in an evening snack. These five meals help the body to remain in the Zone all the time (the hormonal cycle takes between 4-6 hours), without excessively overloading digestion.

The Zone formula. Having established the link between proteins, carbohydrates and fats we obtain the correct make-up of macronutrients in the Zone diet: 40% carbohydrates, 30% proteins and 30% fats.

A final note. Having described the Zone diet to you we would like to point out that we have not wished to offer an opinion of its worth, as maintained by Sears. In fact the concept put forward by the American biochemist has been met with controversy from the international scientific community.