As for the optimal frequency of meals, it differs depending on whether a state of ketosis has been established or not.

The right frequency of meals in the non-ketogenic diet

  When the organism is not in a state of ketosis, the cells mainlyuse glucose for nourishment, glucose that they take from the blood, while muscle and liver glycogen reserves, being, as we have already seen, rather limited, are rarely used by the organism. During a period of fasting, glycaemia will gradually tend to drop, and with it insulinemia, bringing the amount of sugar in the blood to such a low level that the body is alarmed. In fact, as we have said, not only can glycaemia not exceed a certain limit, it cannot drop too much either. This is why the hormone that antagonises insulin is released into the blood: glucagon. This hormone has the exact opposite function to that of insulin, i.e. it signals to the cells that they need to release the glucose they have inside them into the blood in order to increase blood sugar levels. However, when blood glucose is very low, cells lose, at least in part, their responsiveness to glucagon. In fact, once they run out of glucose that can be taken from the blood, they too run out of nourishment. Hence, in order to prevent hypoglycaemic coma, the organism will activate gluconeogenesis, a process we have already encountered when discussing metabolism and reactive hypoglycaemia, resulting in loss of muscle mass and preservation of fat mass. It should be noted, however, that even if the cells deplete their glycogen reserves to increase glycaemia, the glucose that would be poured into the blood would soon be depleted again (it would be enough to fast for a few more hours at most), given the meagreness of the supply, hence a new onset of hypoglycaemia. The problem, therefore, would not be solved, except for a short time. It is clear, therefore, that if the goal is to increase physical fitness, intermittent fasting is not a good eating strategy in the context of a high-carbohydrate diet. On the contrary, the best thing to do is to regularly provide the body, every two or three hours, four at the most, with new sources of glucose (carbohydrate-based foods) or protein to turn into sugar, without the need to destroy muscle tissue. In this way, just when blood glucose is getting low enough to require glucagon intervention, the digestive system will pour new glucose into the blood, causing blood sugar levels to rise. Of all meals, breakfast is the most important. In fact, as soon as the sleep period is over, you are at a point where you have been fasting for at least as long as you slept. And this period exceeds (or, at least, so it is hoped) by at least double that interval of a few hours recommended above.

Managing blood glucose by controlling the glycaemic load

  While it is important to eat micro-meals (snacks) regularly, so as to provide the body with a constant amount of glucose, it is essential to avoid eating too many carbohydrates in a single meal. Doing so, in fact, runs the risk of running the risk of reactive hypoglycaemia. The most important parameter for keeping the amount of carbohydrates consumed in the context of a single meal under control is the glycaemic load. The higher the glycaemic load, the quicker the blood sugar spikes and the more drastic its consequences in terms of reactive hypoglycaemia. It is desirable to keep the glycaemic load as low as possible by taking these precautions:

• favour foods that have a low glycaemic index;
• increase the frequency of meals as much as possible, in order to distribute the calories (and carbohydrates) to be consumed daily;
• reduce the amount of carbohydrates consumed in each meal as much as possible.

The right frequency of meals in the ketogenic diet

  We have seen that the ketogenic diet has, among its various purposes, the function of directing the metabolism to preferentially consume first ketone bodies and then fatty acids. If, therefore, one is in a state of ketosis, the fact that glycaemia is low (or due to fasting, or abstaining from carbohydrates) does not matter much: in fact, the cells will prefer to burn fats rather than glucose, so, in any case, gluconeogenesis will not take place, except to a very small extent. If, therefore, you are on a ketogenic diet, the frequency with which you eat is not that important. In fact, under certain conditions, fasting might even be a better choice.

Controlled fasting to lose weight

  Let us now take a look at what happens to the body when, in a state of ketosis, one fasts. During abstinence from food, levels of a hormone called cortisol, also known as the ‘stress hormone’, rise. This name is due to the fact that cortisol tends to increase its concentration in the blood stream under all circumstances that cause physical (including demanding sports training) or psychological stress. Now, the list of such factors also includes fasting. Cortisol is usually seen, especially by bodybuilders, as a negative substance that can damage fitness, as it is capable of establishing a catabolic state and causing gluconeogenesis. When the levels of this hormone increase only for a short period (precisely that of controlled fasting), however, it can have a positive influence on body composition. Specifically, cortisol promotes the secretion of the hormone noradrenalin, which, in turn, suppresses the sense of hunger. It is understandable that the maxim that ‘the less you eat, the less hungry you will be’ may sound like a paradox, but in fact, within certain limits, it is precisely the truth. Furthermore, cortisol has a stimulating function on the body: it increases attention, reflexes and energy. This is not surprising, given the (supposed) biological function of cortisol, which is to prepare the body for an incipient stressful situation. During such a situation, in fact, feeling the pangs of hunger, or experiencing fatigue and tiredness would serve no purpose. Fasting, therefore, contrary to what one might think, can in certain circumstances even increase available energy. It is essential, however, that it does not last longer than six or eight hours, at the end of which a hearty meal should be eaten, the quality of which must be such that it does not compromise ketosis (in other words, it must be low-carb, except for short periods of carbohydrate recharging). Fasting for longer can have counterproductive effects: although stress is a physiological reaction of the organism to a pressing need (being stressed means being alert, ready and combative), in an ideal situation the stress-causing agent, and thus the rise in blood cortisol levels, should disappear very quickly. If the effect of the stressor on the organism is of relatively long duration, it can become pathogenic, leading to a full-blown syndrome. Such a condition has completely different connotations than a short-term rise in cortisol levels and is likely to significantly damage both physical fitness and body composition. When stress lasts for a long time, because cortisol has an antagonistic effect to that of insulin (causing an increase in blood sugar), the amount of sugar in the blood tends to approach the upper limit of physiological values. This causes an increase in insulin secretion, which tends to restore basal (normal) values. Cortisol, however, remains high due to fasting and therefore, in order to compensate for its effects and maintain normal blood sugar levels, the endocrine pancreas is required to constantly release copious amounts of insulin into the blood. In this scenario, cortisol and insulin compete with each other and insulin resistance occurs, hence the fattening. In addition, cortisol exerts an inhibitory function on the secretion of CRH (corticotropin-releasing hormone), which has an anorectic effect. This increases appetite (so-called ‘stress hunger’). Cortisol, when chronically elevated in the blood, also stimulates the secretion of neuro-peptide Y, a substance that has a stimulating function on appetite. All these actions combined can completely ruin an eating strategy. If, then, fasting is prolonged further despite the appearance of the aforementioned effects, a second phase takes place, that of true ‘nervous exhaustion’. During this phase, the action of insulin tends to prevail over that of cortisol, which nevertheless remains constantly present in abundant quantities in the blood stream. This therefore causes hypoglycaemia. This situation implies an increased stress on the hypothalamic appetite centres, which, as their name suggests, have precisely the function of increasing the sense of hunger. Stress hunger, therefore, increases. Finally, during the nervous exhaustion phase, aldosterone levels also increase, another hormone that increases the craving for sugar-rich foods. In conclusion, then, fasting, under certain conditions, can be a powerful ally, not only for improving fitness and body composition, but also for being more active and energetic. One must, however, know how to do it.