Short-term fasting

Basic Guide for Beginners

Fasting (fasting) is a practice involving complete abstinence from eating or refusing specific foods for a certain period of time. It has been practiced for many centuries, mainly for religious reasons.

In recent years, short-term (cascade) fasting has become increasingly popular among people who want to reduce body weight or improve their health.

There are various options for short-term fasting, some of which are described below. In general, this approach implies partial or complete restriction of the intake of calories into the body for 1-4 days a week, while on the remaining days a person returns to a normal diet. Adherents of short-term fasting claim that such a diet is more rational than traditional diets.

Fun facts about short-term fasting

• researchers have not come to a consensus on the optimal method of short-term fasting;

• short-term fasting may be more effective for weight loss than for muscle building;

• fasting can affect the progression of cancer, as well as the response to antitumor therapy;

• Studies have shown that people who adhere to a short-term fasting regime can simultaneously undergo a moderate-intensity exercise program.

The main methods of short-term fasting

The regimens may vary in frequency and duration of fasting periods. Dr. John Berardi, who is an expert in the field of sports physiology and nutrient biochemistry, has experimented with various short-term fasting regimens. He published his results in the book Experiments with Intermittent Fasting. Below is a summary of some of the modes he proposed.

Fasting every other day

Dr. Krista Varady from the University of Illinois based on the results of her research has developed a diet "every other day". According to its name, this regime implies alternating days of "fasting" and "uncontrolled eating". On fasting days, a person is limited to eating 500 calories worth of food at lunchtime. The rest of the days he can eat anything, anytime, and as much as he wants.

Another fasting regime every other day implies a complete refusal of food every second day.

Fasting for two days a week

The diet developed by Dr. Michael Mosley consists of fasting for two days a week. On fasting days, women limit their diet to 500 calories, and a man – 600 calories. For the remaining five days, both adhere to their usual diet.

Daily cascade fasting

Daily cascade fasting limits meals to a certain number of hours throughout the day. The most common is the 16:8 diet. It involves refusing food for 16 hours a day, which leaves an 8-hour window for eating. Daily cascade fasting is also often referred to as a time-limited diet.

Potential positive health effects

Proponents of short-term fasting claim that this approach can help achieve a number of positive changes:

Longevity

A number of studies have revealed the relationship between short-term fasting and a longer, healthier life.

Several long-term animal studies have revealed a relationship between calorie restriction, reduced morbidity and increased life expectancy. Scientists are trying to understand the mechanisms that cause these positive effects, and the possibility of transferring the obtained data to humans.

Insulin-like growth factor-1 (IGF–1) is a hormone associated with a number of diseases that affect life expectancy, such as cancer and type 2 diabetes. Some experts claim that eating stimulates the production of this hormone. Fasting can be considered as a way to reduce IGF-1 levels, which should potentially help reduce the risk of developing chronic diseases and increase life expectancy.

Cancer

Studies have shown that calorie restriction of food reduces IGF-1 levels, which helps to slow down the growth of tumors. A very small clinical study involving cancer patients has demonstrated that fasting reduces the severity of certain side effects of chemotherapy, including weakness, nausea, vomiting and diarrhea.

Due to the potential negative side effects, prolonged adherence to a low-calorie diet is not recommended for people with malignant tumors. A short-term reduction in the amount of calories consumed, such as short-term fasting, may be an acceptable option for this group of people.

Neurological diseases

Short-term fasting can also have an impact on cognitive function. In a study on mice carrying genes predisposing to Alzheimer's disease, cascade fasting improved the results of indicators of age-related cognitive decline.

Blood sugar levels

Some studies have shown that short-term fasting improves tissue sensitivity to insulin better than traditional diets, while other studies have obtained comparable results. The researchers also obtained data that short-term fasting and traditional diets provide comparable levels of hemoglobin A1c reduction.

Are there any potential health risks?

Short-term fasting is not suitable for everyone. According to Dr. Mosley, short-term fasting is not recommended for people with the following conditions:

• body weight deficit;

• eating disorders;

• type 1 diabetes mellitus;

• type 2 diabetes mellitus, controlled by medication;

• pregnancy or breastfeeding;

• recent surgical interventions;

• mental disorders;

• fever or acute illness;

• conditions in which warfarin is prescribed.

The disadvantages of fasting described in the book Experiments with Intermittent Fasting include:

• mood swings;

• very strong hunger;

• decline of strength;

• obsessive thoughts about food;

• impulsive gluttony.

However, most people describe these feelings and changes in behavior only during the first weeks of fasting.

Will it help with excess weight?

In a study involving older men, the effects of diet 5 were compared:2 (regular meals 5 days a week and fasting 2 days a week) compared to a traditional diet for weight loss, as well as changes in laboratory parameters.

Both diets provided equally significant weight loss.

In a review of studies comparing short-term fasting with traditional diets, similar results were obtained. Diets of both types provided a comparable reduction in body weight.

Does it help to build muscle mass?

Most weight loss protocols lead to a certain reduction in fat-free body weight. Exercise and eating an adequate amount of protein can help in maintaining fat-free body weight in dieters.

A study involving men undergoing a strength training program showed that short-term fasting provides a significant reduction in the amount of body fat. At the same time, in men on a regular diet, there were no significant changes in the amount of fat in the body. Participants in both groups retained their fat-free body weight.

The most frequently asked questions for beginners

Is it possible to continue playing sports?

In an interview with the Atlantic magazine, Dr. Varadi said that after 10 days, the activity level of people who adhere to the fasting plan "every other day" is compared with the activity levels of people who adhere to a traditional diet or do not follow special dietary regimes. Also, the most useful are workouts that end an hour before meals.

Will I overeat on days of uncontrolled eating?

According to Dr. Varadi, the number of calories consumed by people on such days does not exceed their energy needs. However, they do not eat enough to make up for the deficit formed during the days of fasting. At the same time, other researchers note that people inadvertently reduce their diet in the days between fasting days.

Will I feel hungry during the days of fasting?

Dr. Varadi claims that the most difficult are the first 10 days of fasting every other day. Calorie-free drinks, such as sugar-free tea, can help in dulling hunger.

Is it necessary to continue fasting when reaching the desired weight?

Some fasting regimes, such as the "every other day" diet, have a weight maintenance phase, which implies an increase in the number of calories consumed on fasting days from 500 to 1,000. Other plans recommend reducing the number of fasting days per week.

What should I pay attention to before trying short-term fasting?

People interested in short-term fasting should evaluate the compatibility of this approach with their lifestyle. Fasting exposes the body to stress, so it may not benefit people who are already exposed to significant stressful effects.

Special occasions and social events are usually tied to meals. Therefore, short-term fasting may prevent participation in such activities.

People training to participate in endurance competitions or other competitions involving intense physical activity should be aware that short-term fasting can affect their results in cases where the competition or training falls on the day of fasting.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Medical News Today: Intermittent fasting: The ultimate beginner's guide.

25.09.2017