Intermittent Fasting
What is Intermittent Fasting?
Intermittent Fasting refers to no or very limited calories intake within regular periods. It commonly consists of a daily fasting for 16 hours, which called 16:8 intermittent fasting, or a fast 2 days per week on non-consecutive days, which called 5:2 intermittent fasting.
During fasting periods, caloric consumption is limited to 0-25% of daily caloric needs. Water, and other no-calorie beverages, such as plain coffee and tea, are allowed to obtain.
During non-fasting periods, it can be at will to consume food, restricted to a certain diet composition, or aimed to reach a specific caloric intake of up to 125% of daily caloric needs.
16:8 Intermittent Fasting
This fasting method is also called the Leangains Diet, which fasting for 16 hours a day, and leaving an eating window of 8 hours.
Generally, people finish their evening meal by 8p.m. and start fasting until noon on the next day. You are also encouraged to pick the time frame that fit your own schedule.
Benefits:
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Easier to follow
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Lose weight
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Less restrictive and more flexible
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Work on most lifestyle
5:2 Intermittent Fasting
It is also called the Fast Diet. This fasting method allows people to have regular diet for 5 days, while the other two days have restricted caloric intake of 500-600 per day.
People can freely choose which two fasting days, as long as they are non-consecutive days. Generally, people will plan to fasting on Monday and Thursday. Also, you are encouraged to find two days that fit your lifestyle and schedule.
Benefits
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No requirement on food sources
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Easier to follow
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Lose weight
Overall Benefits
Not focusing on specific types of intermittent fasting, but the whole intermittent fasting method is beneficial to our body:
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Easier to follow - Low food sources and calorie restriction
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Reduce insulin level
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Reduce insulin resistance
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Improve insulin sensitivity
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Improve blood sugar control
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Lose weight
Other Concerns?
Although intermittent fasting has several benefits, it also has potential side effects and may not fit everyone.
Overeating and potential weight gain
Restricting intake in certain period may lead to overeating than usual during eating period. Some people may feel overwhelming hunger during the first few fast days, which causes them to eat more during eating periods. This may lead to weight gain, digestive problems and unhealthy eating habits.
Short-term physical symptoms
During the first few fast days, you may feel uncomfortable, such as hunger, weakness and fatigue. The situation will be better once you get into a routine. However, if the symptoms sustain, you may need to seek for medical advice.
Adequate nutrition intake
You have to ensure you obtain sufficient amount of nutrients for body functioning, especially on 5:2 fasting days. You are recommended to eat nutritious, high-fibre, high-protein food, which make you feel full and rich in nutrients.
References:
1. Welton, S., et. al. (2020). Intermittent fasting and weight loss. Canadian Family Physician 66 (2) 117-125.
https://www.cfp.ca/content/cfp/66/2/117.full.pdf
2. Leonard, J. (2020). Seven Ways to do Intermittent Fasting. Medical News Today.
https://www.medicalnewstoday.com/articles/322293
3. Streit, L. & Link, R. (2021). What Is 16/8 Intermittent Fasting? A Beginner's Guide. Healthline.
https://www.healthline.com/nutrition/16-8-intermittent-fasting
4. Bjarnadottir, A. (2018). The Beginner's Guide to the 5:2 Diet. Healthline.