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Fasting or being on an exclusive water diet for a specific period of time is a convenient method for weight loss. It typically entails a steady abstinence of food and beverages. It may require complete abstinence, or allow a reduced amount of food and beverages.
An alternative solution is Intermittent Fasting. Intermittent fasting is a diet regimen or a timed approach to food that cycles between brief periods of fasting or calorie reduction and periods of unrestricted eating. It promotes change in body composition by loss of fat mass and weight, improving health indicators like blood pressure and cholesterol levels. Unlike long term low-calorie diets that cause physiological changes that causes the body to prevent further weight loss, intermittent fasting copes by cycling between a low-calorie level for a short time and normal eating.
Intermittent fasting can be very effective in weight loss. One study shows that most people try intermittent fasting to help lose weight. Several studies indicate that short-term intermittent fasting up to 24 weeks leads to weight loss in overweight individuals. People who fast have also been shown to lose more visceral body fat than people who follow calorie reduction diets.
Effects of Fasting
- Reduces insulin level, makes it easier for the body to utilize stored fat, and lowers blood sugar.
- Lowers blood pressure, cholesterol, triglyceride, and inflammation levels.
- Changes expression of certain genes, thereby protecting from diseases and increasing longevity.
- Drastically increases Human Growth Hormone, which helps utilize body fat and growth of muscles.
- Activates autophagy (digests or recycles old and damages cell components)
- Helps in weight loss
- Prevents cancer
- Increases brain health by stimulating production of brain-derived neutrotrophic factor, suppressing depression and other brain issues.
- Research also shows benefits in management of metabolic syndrome, extending lifespan, protecting neuron function and shows promise in digestive diseases.
Side-effects of Fasting
- For a healthy, well-nourished person, intermittent fasting does not give any significant side-effects.
- Beginners may feel light physical and mental lethargy as body adjusts.
- Stopping intake of caffeine, excessive sugar and alcohol can cause headaches.
- Nausea and dizziness due to hunger.
People who should refrain or get medical supervision while fasting:
- Pregnant women
- Nursing mothers
- Those trying to conceive
- Individuals with Low blood pressure
- People on medications needing food intake
- Stage of active growth in adolescents.
- People with eating disorders including anorexia, bulimia nervosa
- Underweight individuals
Ways of Intermittent Fasting:
1. Time-restricted feeding/Leangains protocol
A planned meal every day with a designated time frame for fasting.
Example: In the 16:8 method, men fast daily for 16 hours and women for 14-15 hours. This creates an 8-10 hour “eating window” for multiple meals. A shorter fasting period is recommended for women as they are shown to work better. Meals are eaten from 8 AM to 3 PM, with fasting during the remaining hours of the day including sleep time. It was popularized by fitness expert Martin Berkhan.
2. Whole-day fasting
1-2 days per week of complete fasting or up to 25% of daily calorie needs, with no food restriction on the other days.
Example: The 5:2 diet approach advocates no food restriction for five days, coupled with a 400-600 calorie diet the remaining two days of the week. Popularized by British journalist and doctor Michael Mosley.
3. 24-hour fasting/ Eat-Stop-Eat
Keep a 24 hour fast once or twice a week.
Example: finishing dinner at 7pm and not eating until 7am the next day. Popularized by fitness expert Brad Pilon. It may prove difficult for beginners, hence start with a 14-16 hours and gradually increase the hours of fasting.
4. Alternate-day fasting
Alternating days of no food restriction with days that include one meal that provides about 25% of daily calorie needs or 500 calories or a complete fast.
Example: Mon-Wed-Fri consists of fasting, while alternate days have no food restrictions.
5. The Warrior diet
A regulated amount of fruits and vegetables during the day, followed by one huge meal at night. It was popularized by fitness expert Ori Hofmekler.
6. Spontaneous meal skipping
A “natural” way to do intermittent fasting. Skip 1 or 2 meals when you don’t have the time to cook or eat or don’t feel hungry. Make sure to eat healthy when you do.
What and how to eat during the eating window?
- Water, coffee and other non-caloric beverages can help reduce hunger levels.
- Eat healthy food
- Avoid junk food as calorie-rich diet may not work to achieve the target.
- Eat normal amount of food (as one would in a non-fasting period)
- Calories count, and food quality is significant.
Studies on effectiveness of intermittent fasting
1. A systemic review of 40 studies has showed that intermittent fasting was effective to lose 7-11 pounds over 10 weeks.
2. A randomized controlled trial that followed 100 obese individuals for one year did not find intermittent fasting to be more effective than daily calorie restriction.
3. At this time, it is difficult to draw strong conclusions about the benefits or drawbacks of intermittent fasting for weight loss. More studies are required to concretely make any statements or demonstrate any direct effects.
Based on only 3 studies, alternate day fasting appears to result in weight loss as well as reduction in glucose and insulin levels.
4. Considerable observational data on various forms of religious fasting shows that they result in transitory weight loss with mixed impacts on health, increase in immunity power and on other biomarkers.
5. Modified alternate day fasts result in reduced weight in controlled groups ranging from 3.2% over a period of 12 weeks while it showed 8% in a 8 weeks duration.
Fasting for weight loss – Easy and sustainable
This overview suggests that fasting regimens may be a promising approach to lose weight and improve metabolic health in people.
Make sure to plan the meals during the eating window and eat healthy amount of food. Fasting for 8-12 hours helps achieve a steady state for many metabolic substrates. Therefore, an adoption of intermittent fasting regimen is a feasible and sustainable strategy for promoting health.