What is Intermittent Fasting?
Intermittent fasting (IF) is an eating strategy wherein you fast for several hours and then have regular food again. It is not what you eat; it is when you eat.
It usually consists of a cycle of fasting and non-fasting over some time. Various intermittent fasting models exist, but all have their days or weeks divided into eating and fasting periods. For example, you can eat normally for a week and some days,eat for 8 hours and fast for 16 [1, 2, 3, 4, 5].
What Does Intermittent Fasting Do?
Intermittent fasting has many health benefits. It effectively manages weight, fasting insulin, and blood glucose.
It also turns on a host of biological pathways to promote:
- Autophagy and cell renewal
- Slow the growth and spread of cancer cells
- Slow down senescence.
IF increases stress tolerance, which is further enhanced by exercise. It also influences many pathological disorders such as cancer, obesity, diabetes, cardiovascular disease and neurodegenerative disorders.
When we eat very sparsely, the human body undergoes a metabolic change as liver glycogen is used up. This induces a transition to using the fatty acids and ketones in the body and thus positively influences adiposity, longevity, and the immune system for diseases [6, 7, 8, 9, 10].
Risks of Intermittent Fasting?
Intermittent fasting (IF) is a typical diet regimen in which people alternate between eating and fasting. It has been linked to various health advantages, but it is not without its risks and side effects.
Disordered eating is one of the significant risk factors for IF. Impulse control difficulties, according to a study, slowed the correlation between IF and disordered eating behaviours, suggesting that IF is associated with increased disordered eating behaviours.
Another risk is the potential short-term mortality risk. One study reported that IF raised the 1-year Intermountain Mortality Risk Score (IMRS), so fasting may increase mortality risk in the short term [16].
Other adverse consequences and restrictions on IF can affect patients of a particular age and sex. The health benefits and safety of IF require more research [1].
Last but not least, although IF has been associated with a reduced incidence of type 2 diabetes mellitus complications, we are still unaware of the long-term effects of IF on prediabetes [17].
What is Cortisol?
Cortisol is a steroid hormone the adrenal glands release when we experience stress and low blood glucose. It’s a stress regulator in the body and is sometimes called the "stress hormone" [18, 19, 20, 21, 22].
Cortisol also affects other physiological functions. It is suitable for metabolism, inflammation, and immune function. It is also essential for the "fight-or-flight" response, a biological and defensive reaction to a threat or threat. This response is for energy, ensuring you are awake and preparing your body to respond to the threat [18, 19, 20, 21, 22].
Cortisol increases blood glucose levels, the utilization of glucose by the brain, and the access to repair-supporting substances in metabolism. It also tampers with non-life functions when death is imminent [19].
Cortisol also affects the immune system. It causes the apoptosis of proinflammatory T cells, prevents antibody secretion by B cells, and prevents the movement of neutrophils during inflammation [23].
When a stress response is present, cortisol is secreted from the adrenal cortex, and the body goes into hyper-alert mode. Simply put, cortisol's catabolic reactions fuel the body [23].
Cortisol also regulates mood. Some studies found within-body increases in cortisol that translated to further increases in activeness, alertness and relaxation, and lower levels of stress and nervousness [24].
Does Intermittent Fasting Influence Cortisol Levels?
Intermittent fasting—eating and fasting alternately—can affect cortisol. We call cortisol the "stress hormone," and it is a vital part of many bodily processes, such as metabolism and the immune system.
It turns out that fasting can raise cortisol. A study revealed that total and free cortisol rose in 22 healthy volunteers who participated in a 10-day fast [25]. In a similar study, caloric restriction was strongly associated with serum cortisol in 13 studies of 357 subjects [26].
However, the effects of fasting on cortisol could vary with the amount and type of fast. A 5-day fast, for example, produced 1.8 times more endogenous 24-hour cortisol [27]. Ramadan Intermittent Fasting, on the other hand, caused a significant drop in morning cortisol [28].
Even more so, the impact of fasting on cortisol can depend on gender and BMI. For instance, cortisol increased more dramatically during fasting in men and people over 25 with a BMI [29].
Intermittent fasting has the potential to modulate cortisol, although it depends on several variables as to how much and how far that modulation will be felt. However, more research is needed to understand the connection between intermittent fasting and cortisol.