Intermittent fasting, as the name implies, consists of alternating periods of fasting with periods of feeding.
Although lately it is considered a diet, specialists discard this categorization and prefer to speak of a nutritional model of caloric restriction.
The goal of this practice is to obtain different health benefits, but how effective and safe is it? Here we are going to review its main characteristics.
The effects of intermittent fasting, a practice of cyclically alternating periods of meals and fasting, have been studied for years.
The available evidence indicates that this nutritional model could function as a preventive and therapeutic approach against different diseases and conditions. Among its main benefits we find:
- Help control weight, preventing overweight or obesity.
- Promote neuronal plasticity (ability of the brain to recover and restructure).
- Improve control of our appetite.
- Improve glucose use and insulin sensitivity.
- Prevent the development of cancer cells.
- Reduce the indicators of inflammation.
- Reduce cholesterol and triglyceride levels.
- Delay aging, both physical and mental, and reduce mortality.
There are clinical trials that have proven that intermittent fasting can help you lose weight when you practice it:
- Eating for 8 hour periods and fasting for the remaining 16 hours.
- Eating healthy for five days a week, and restricting the remaining two (not consecutive) caloric intake.
Weight loss is due to the fact that, on an empty stomach, the glucose stored in the liver is slowly consumed (about 700 calories), which takes between 10 and 12 hours to be used.
When you eat three or four times a day, you can’t use that “deposit.”
- Possible Health Benefits of Intermittent Fasting
Much of the evidence for the benefits of intermittent fasting also comes from animal studies.
An example of this is the work published in the magazine Cell Research, which found potential in intermittent fasting to increase metabolism and burn fat.
For 16 weeks, the authors compared the diet of two groups of mice: some ate normally for two days and then went a full day without food, while the other group ate the same number of calories, albeit evenly over three days.
After the evaluation period, they found that the fasted mice tended to have lower body weight, as well as less white fat and more brown fat. The latter is used to obtain energy and body heat.
Intermittent fasting was also associated with greater stability of glucose and insulin levels.
Other research published in Cell Reports, showed that intermittent fasting could help to reprogram many cellular responses, promoting health and general function of the body, while preventing diseases linked to aging.
However, the mechanisms behind this, as well as other benefits associated with intermittent fasting, are not yet known with certainty.
Types of intermittent fasting
There are different intermittent fasts, depending on the feeding cycle that is carried out:
It consists of consuming 500 calories for two days a week, while the other five days a healthy and normal diet is followed.
To more easily specify fasting patterns, experts advise incorporating fiber and protein, to extend the periods of satiety between meals.
Remember: fasting days should never be consecutive.
Alternative fasting day
Fasting is done every two days, consuming only 500 calories or the equivalent of 25% of the normal intake (there are even cases in which zero calories are chosen). On non-fasting days, the diet should be healthy and normal.
Restrict food for time
This form of fasting, also known as 8/16, consists of fasting for 16 hours a day, and then eating for the remaining eight hours.
Since the sleep period lasts about eight hours, this method is easier to adhere to and has become very popular. It is advised not to skip breakfast when waking up.
One day fast
It consists of stopping eating for 24 hours and is practiced between one to two times a week. To specify this nutritional model, fasting is usually started after breakfast, until breakfast the next day, or from lunch to lunch.
Certain side effects linked to this practice have been recorded, such as headaches or body aches, fatigue, hunger, irritability, and low energy.
Risks of intermittent fasting
Intermittent fasting is a widespread practice in the world, but health professionals explain that many people may not tolerate or sustain it, exacerbating problematic relationships with food.
Although it appears to work for weight loss, its other benefits are still under discussion. In addition, those who do intermittent fasts may experience increased sensitivity to temperatures, poor work, physical and mental performance, irritability, general pain and fatigue.
Intermittent fasting is not advised for pregnant women, children, and people at risk for chronic diseases.
Until there is significant scientific evidence from human trials, people interested in using herbal therapies and supplements should exercise extreme caution.
Do not abandon or modify your medications or treatments, first talk to your doctor about the potential effects of alternative or complementary therapies.
Remember, the medicinal properties of herbs and supplements can also interact with prescription drugs, other herbs and supplements, and even alter your diet.
Sources consulted: Academy of Nutrition and Dietetics, Comprehensive Natural Medicines Database, US National Library of Medicine, Mayo Clinic, National Institute of Complementary and Alternative Medicine.