In recent years we hear a lot about fasting and calorie restriction . In reality, these are not new concepts. Fasting is present in all religious traditions and the first studies on the effects of a reduction in food intake date back many decades.

Ancient traditional practices were predominantly aimed at strengthening the spirit and willpower à . The often mentioned hypotheses of detoxifying and purifying the body are quite scientifically fanciful. A prolonged fast is, if anything, a cause of toxicity and danger to the body.

However, we now know that limiting the consumption of calories without penalizing the intake of nutrients can help reduce the risk of certain diseases and extend life.

A calorie deficit generates a signal that is called hormetic. It is a stressful agent that stimulates a protective response that helps our body’s cells to repair their damage and strengthen themselves.

The mechanism is very similar to what is obtained by following a correct physical training program that includes a specific relationship between stimulus and recovery. And here lies the limit of the fasting and calorie restriction protocols that have become popular these days: we don’t know what effects they have on the individual and how to monitor them.

In the case of physical training it is possible to evaluate in some way the body’s response to workloads, but in any case it is not difficult to train too little or too much. In the first case there will be no effect while in the second there may even be damage. The same can happen by reducing food intake.

If we could calibrate and customize the protocol, we could assume that it would elicit a positive response in the body, but in practice we don’t know. If, on the other hand, the stimulus was excessive it could even cause damage.

On the endocrine level fasting or drastically reducing calories stimulates a stress response with an increase in cortisol, a hormone that leads to the destruction of muscle tissue and a weakening of the immune system.

One of the most popular practices is the 16-hour fasting protocol and an 8-hour meal window (intermittent fasting). Even in this case, however, there is no evidence that this practice is suitable for everyone. Indeed, on the behavioral level it could even generate effects of loss of control over nutrition linked to hunger crises and on energy, drops in performance and concentration.

There are a few things to keep in mind:

1. There is evidence that calorie restriction and fasting (particularly intermittent fasting) can reduce the risk of some diseases and extend life. This mechanism is linked to the lowering of insulin levels and the triggering of cellular repair processes induced by the hormmetic mechanism and the stress response.

2. However, the stress response itself could be excessive and generate cell damage and an exaggerated production of cortisol.

Fasting and calorie restriction are therefore not protocols for everyone and are not therapeutic miracles as they are described in some cases.

They can be used under medical supervision in healthy individuals who are sufficiently skilled in managing their nutrition. They are therefore interventions that should always be personalized and that possibly represent “improvements” and not initial steps in improving quality à food and life.

The key steps remain to eat better and regularly, exercise every day and manage stress.

If you still want to learn more about intermittent fasting, download my free report ” Intermittent Fasting: Questions and Answers “.