Today we will talk about the well known ZONE DIET.
It is a diet invented by Barry Sears, the American who dedicated his studies to the interaction between nutritional molecules and the hormonal response of the human body.
The zone diet was born as a nutritional therapy aimed at improving the state of health. However, her "trump card", that is the aspect that made her famous all over the world, is the great EFFECTIVENESS in contrasting overweight.
Obviously, as with many "innovative diets", BEHIND THE MOST NOBLE INTENT there are several negative aspects that should be taken into account.
Precisely for informational purposes, with the next slides we will try to deepen the ORIGINS, OBJECTIVES, APPLICATION, ADVANTAGES and DISADVANTAGES of the famous ZONE DIET.
As anticipated, the ZONE DIET is the result of studies carried out by research biochemist Barry Sears. The American, also president of the “RESERCH INFLAMMATION FOUNDATION”, investigating the reactions between nutritional molecules and the body's hormonal response, examined some INTERACTIONS responsible for the onset of the so-called diseases of well-being.
More precisely, according to Sears, the aspects to be taken into account are essentially 2:
- the control of INSULIN, that is the anabolic hormone responsible for adipose accumulation
- and the control of EICOSANOIDS, that is the PSEUDO-HORMONAL molecules responsible for the increase and reduction of INFLAMMATION
- Area as a "range of psychophysical well-being"
- and "RANGE of OPTIMAL concentration of INSULIN in the blood"
The means used in the zone diet are: correct nutrition (and below we will understand WHICH), weighted motor physical activity, management of psycho-physical stress and integration of essential fatty acids of the omega 3 group.
Trying to simplify the CONCEPTS as much as possible to obtain greater comprehensibility, we list the objectives of the zone diet:
- Moderate blood sugar
- Optimize the INSULIN-GLUCAGON ratio
- Optimize the ratio of INFLAMMATORY EICOSANOIDS-ANTI-INFLAMMATORY EICOSANOIDS.
First of all, to moderate blood sugar it is necessary to bring a lower amount of carbohydrates than, for example, the Mediterranean Diet. Furthermore, these carbohydrates must be in small portions, that is, with a low glycemic LOAD, and with a low glycemic INDEX. With less blood sugar you also get a lower release of INSULIN. Then, according to the zone diet, it is also NECESSARY to associate a portion of proteins with carbohydrates, which in turn facilitate the release of GLUCAGONE, or the hormone that counteracts the rise of insulin itself. We remind you that insulin is a hormone produced by the pancreas which, if in EXCESS, has a GREASING function and promotes the release of the INFLAMMATORY EICOSANOIDS which are in turn responsible for the ATERO-SCLEROSIS.
Within the same meal, in addition to carbohydrates and proteins, it is also necessary to insert a portion of mainly unsaturated lipids (or GOOD FATS), as they are beneficial and protective against dyslipidemia and atherosclerosis. These can be included in both foods of animal and vegetable origin.
Furthermore, to fully achieve the above objectives, the zone diet suggests using abundantly foods rich in dietary fiber, mineral salts, vitamins and antioxidants. We remind you that dietary fiber, lecithins and phytosterols have a HYPOCHOLESTEROLEMIZING function and that certain vitamins (i.e. A, C and E), certain mineral salts (i.e. Zinc and Selenium) and various plant phenolic substances, all possess a remarkable ANTIOXIDANT function.
The zone diet does NOT take into account the energetic importance of nutrition, but rather the metabolic impact of the nutrients contained in foods; however, as we will see later, this is simply a HALF TRUTH!
Now that we have clarified the health goals of the Zone Diet, let's try to understand how to translate them into foods. I immediately warn all kind listeners that this is NOT a simple concept to understand, and at the same time I apologize to all those who know it for the lack of accuracy with which I will describe it.
First of all, it is not advisable to fast for more than 5 hours, which is why the dietary organization provides at least 4, but better 5 or 6 meals a day. Each meal, main or secondary, must respect an ENERGY DISTRIBUTION of:
- 30% protein (deriving mainly from avian meats, fish, crustaceans, molluscs, egg whites and very lean cheeses)
- 40% carbohydrates (deriving essentially from the fructose of vegetables and fruit, excluding legumes, tubers and cereals with the exception of oats)
- 30% lipids (deriving essentially from cold-pressed vegetable oils, fish, dried fruit).
- Carbohydrates 9g
- Protein 7g
- Lipids 3g
It is then necessary to understand HOW MANY BLOCKS we have to make up our diet. The calculation and algorithms are a bit complicated and, if you want to learn more, I recommend you do it by reading the Sears book. I limit myself simply to specifying that:
- First you need to calculate your lean mass in kilograms
- Then multiply it by a SPECIFIC coefficient based on physical activity
- From this number it is possible to derive the total protein requirement
- This figure, divided by 7, will give us the number of MINI-BLOCKS of proteins
- Finally, by performing the right proportion, the remaining MINI-BLOCKS of lipids and carbohydrates are obtained.
In addition, the management of the meals of the zone diet involves a certain MASTERY. It goes against most of the eating habits of contemporary man and, for this reason, in many cases it fails in the long term.
Then, on a nutritional analysis, the zone diet could be contested in many respects. Regardless of the fact that around the Mediterranean basin the consumption of cereals and legumes represents 50% of the diet, we underline that the Sears food strategy provides for a total energy intake TOO LOW. The Zone Diet prides itself on ignoring the concept of CALORIES and abhors low-calorie diets. It would certainly be an appreciable foundation ... if it weren't for the fact that the ZONE ITSELF is a low-calorie diet! To understand this, it is sufficient to compare a low-calorie Mediterranean diet (at 70% of normal energy) and a zone diet for the same person.
Furthermore, when regular motor activity is recommended, this is not taken into account in the initial estimate and represents a further caloric depletion that worsens the total energy balance.
The intake of carbohydrates is TOO LOW to support INTENSE and PROLONGED physical activity, with the result of a decline in performance and (in the long term) a decrease in the muscle mass involved. It is therefore always necessary to supplement food with malt dextrins in conjunction with physical exercise!
There is also a DOUBLE protein intake compared to the need for a sedentary person. This means that it does NOT predispose (and cannot be adapted) to clinical nutrition in renal or hepatic impairment. Furthermore, in the case of type 2 diabetes mellitus, excess protein in the diet is ITSELF an additional risk factor for the degeneration of renal function related to chronic hyperglycemia.
The intake of fiber and anti-nutritional molecules is often EXCESSIVE; despite the many benefits that can be drawn from the abundance of fruit and vegetables, the excess of the aforementioned molecules can lead to side effects such as: diarrhea and reduction in the absorption of certain mineral salts which are very important for the body.
The need to INTEGRATE with omega 3 to balance the massive intake of omega 6 is an indication of NUTRITIONAL IMBALANCE. According to some research carried out in vitro, an excess of omega 6 can cause the opposite effect compared to what is set by the zone diet; these fats could in fact increase systemic inflammation instead of attenuating it.
Finally, remember that the release of the hormone insulin is NOT exclusive to carbohydrates. The amino acids of the proteins and the fatty acids of the lipids also contribute to the release of these molecules. This probably means that the beneficial effect of the zone on “insulin calm” is more attributable to portion moderation, rather than the 40-30-30 split.
On the other hand, the zone diet can also boast several positive connotations. Among these, the first is undoubtedly an excellent glycemic and insulin index. Caloric scarcity, the promiscuity of energetic macronutrients and the abundance of fructose compared to glucose polymers favor a slow increase in blood sugar and an equally sluggish release of the fattening hormone. Additionally, glycemic moderation PREVENTS the worsening of bad LDL cholesterol levels.
The intake of dietary cholesterol and saturated fat is very low. It is a protective factor from hypercholesterolemia and therefore also from cardio-vascular compromises.
The intake of monounsaturated and polyunsaturated fats is instead very high. It is a protective factor from hypercholesterolemia, from hypertriglyceridemia, from hypertension, from systemic inflammation and therefore again from cardio-vascular compromises.
The supply of dietary fiber is such that it can guarantee an excellent prebiotic function, purifying from waste and therefore protecting against bowel cancer.
Finally, the supply of vitamins, mineral salts and antioxidants is very high, with a consequent protective effect from oxidative stress and therefore from any form of cancer.
In conclusion, the zone diet is a diet that can promote the recovery of the state of health in sedentary people suffering from alterations in blood lipids, blood pressure and non-serious blood sugar. On the other hand, it is not easily applicable, it is not always well tolerated and (without specific integration) it does not lend itself to the nutrition of the most committed athletes and to clinical ones in conditions of hepato-renal impairment.