Intermittent fasting is trending today, and rave reviews about it are becoming more and more frequent. A paper writer from the essay writing service tried to figure out how this dieting system works and how it affects those who exercise.
What is it?
Intermittent fasting is the voluntary reduction of your “food window,” that is, to 8 hours or less when you eat food.
This does not mean that you have to eat continuously for 8 hours. During this time, you eat as usual, and during the fasting hours, you abstain from food (any non-caloric drinks, including tea and coffee, are allowed).
There are several intermittent fasting schemes. The most convenient ones are 8/16 (8 hours – average food, 16 hours – fasting, including night sleep), 4/20, and fasting for 36 hours (night + day + night).
How does it work?
Our cells have a built-in mechanism to utilize and recycle failed organelles – autophagy. Improper or insufficient functioning of the autophagy system leads to premature aging and degradation of tissues. This effect is especially noticeable for nerve cells and internal organ cells.
Drugs can stimulate autophagy, which is now a promising area of research. However, in the case of the nervous tissue, the drug approach is hampered by a particular barrier in the blood vessels of the brain and spinal cord, which prevents most substances from entering the tissue.
At the same time, it has been proved for nervous tissue that periodic starvation (lasting from 24 to 48 hours) sharply increases the number of autolysosomes – organelles utilizing the failed cell structures. Similar results were obtained for liver cells.
Thus, during intermittent fasting, cells are freed from the need to recycle incoming nutrients and can more actively utilize their own failed components, renewing themselves and improving their function.
What do we get?
Blood concentrations of insulin, glucose, and insulin-like growth factor (a substance that accelerates aging and is a risk factor for tumors) decrease.
Animal studies have shown that intermittent starvation reduces the likelihood and slows the growth of neoplasms, including malignant ones. There is much less data for humans, but some positive results are.
Fat burning is one of the most desirable effects of intermittent fasting. Losing weight is trivial due to less caloric intake – you skip one or two meals a day and, accordingly, lose weight. Logically, the weight will decrease only if there is no overeating on regular eating days. If you want to lose weight and maintain muscle mass, it is better to stick to periodic calorie reduction.
In overweight and older adults, cognitive functions improve verbal and visual memory; the number of Alzheimer’s disease markers in the cerebrospinal fluid decreases. Such results were obtained both with intermittent fasting and on a low-carbohydrate diet.
Markers of inflammation and oxidative stress (free radicals) are reduced.
More extended periods of fasting (5-10 days) have been shown to reduce blood pressure in hypertensive patients.
The best-known effects that have made intermittent fasting so famous are metabolic. It increases the cells’ sensitivity to insulin, lowers blood glucose levels, and stimulates the breakdown of subcutaneous fat, in particular the most dangerous – abdominal fat.
Moreover, positive changes in glucose and insulin metabolism have been observed even in people of the standard constitution without accompanying weight loss. Thus, the risk of type 2 diabetes (insulin-independent) is reduced.
Finally, studies in rodents have shown (e.g., here and here) that intermittent fasting and concomitant caloric reduction significantly increase longevity.
Similar studies started the popularity of intermittent fasting. This effect has not yet been sufficiently investigated in humans – too little time has passed since the first publications.
But even if you don’t live one and a half times as long as the mice in the studies – your old age will be much more pleasant thanks to all the above effects.
How does it combine with sports?
The effects of intermittent fasting on professional athletes have not been studied. But there are studies on this topic. This is a study of a religious fast, Ramadan, as close as possible to the “classical” periodic fasting for Muslims.
When we analyze these studies, it turns out that in most sports the results during Ramadan deteriorate. In a study of the athletic performance of untrained men, the results were similar – agility, flexibility, aerobic and anaerobic endurance worsened.
However, these results cannot be completely transferred to traditional intermittent fasting because of the peculiarities of Ramadan. During it, not only eating but also drinking during daylight hours is forbidden. Therefore, people are prone to overeating early in the morning and at night, which disrupts the normal rhythm of sleep and wakefulness. And lack of fluid, especially during intense exercise, leads to dehydration.
At the same time, it has been shown that with sufficient water and nutrient intake even during Ramadan, it is possible to maintain athletic performance at the same level.
On the other hand, a renewal and increase in the number of mitochondria (the organelles that produce energy substances for the cell) during intermittent fasting can increase endurance.
Training in a carbohydrate-deficient state (whether starvation or a low-carbohydrate diet) also stimulates mitochondrial formation. At the same time, muscle volume will not increase.
As a result, scientists conclude that a low-carbohydrate and low-carbohydrate diet (or intermittent fasting) will help to reduce fat mass during endurance exercise, while muscle mass gain requires a high-carbohydrate diet with enough carbohydrates.
And also – that low glycogen content in muscles may not worsen the results, but its high content in endurance exercises improves the results (unexpected, right?).
Another challenge for actively exercising people is to fit the right amount of calories into a reduced nutritional window. It’s one thing if you sometimes leisurely run 5 km and 1500-2000 kcal on intermittent fasting days is enough for you. You can divide them into three meals without any problems.
The situation is quite different for professional athletes who train for several hours every day. You can’t fit 4000-5000 kcal into an eight-hour window that easily. And when you consider the recommended protein intake and intake intervals, things get quite complicated.
What’s the bottom line?
- Intermittent fasting will not help you lose weight if your caloric intake stays the same. If your caloric intake is reduced by intermittent fasting, you have a better chance of losing weight through fat instead of muscle.
- During intermittent fasting, cellular self-repair processes are triggered to prevent type 2 diabetes and metabolic syndrome and help lower blood pressure. There may also be some reduction in the risk of Alzheimer’s disease and neoplasms (complete studies have only been conducted on animals).
- For moderately exercised people, it is pretty realistic to incorporate intermittent fasting into a lifestyle and get all the benefits described.
- When exercising actively (several hours each day), getting the right amount of nutrients may be difficult during intermittent fasting.
- As long as you get a nutritionally adequate supply of calories and nutrients and sufficient fluid intake, your athletic performance will not deteriorate even during periods of intermittent fasting.
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