This is a popular phrase lately. Is it the next health trend or is it truly an improved way of eating? What if a certain way of fasting could lead to weight loss, decreased disease, better mental clarity or even increased longevity? Enter Intermittent Fasting. It is not a diet. It is not starvation. It is not 3 meals a day with snacks in between. It is not a reason to eat junk food when you do eat, ok maybe a little. Fasting has been practiced for centuries in many cultures for many reasons; food shortages or as part of spiritual practices and beliefs.
Intermittent fasting is about when you eat versus what you eat, keeping in mind that meals eaten should be nutritionally dense and primarily plant-based when consumed. It is structured, it is voluntary; it has a beginning and an end. It is eating food at certain times of the day and is a form of calorie restriction. It is an exercise in will-power. In the fasted state, the body becomes more sensitive to insulin. Therefore when you eat food after fasting, your body uses is more efficiently, which can lead to weight loss and muscle creation. IF is for the average person trying to improve their health and may also be attractive to athletes who are looking to attain a certain body composition and/or physical fitness goals.
Many beneficial effects of IF against aging, cancer, cardiovascular diseases, and neurodegenerative diseases have been studied in both animal models and clinical settings. Simply following IF can aid in weight loss instead of following complicated diets. It can be a preventive and therapeutic approach against obesity and metabolic disorders. It can lower blood sugar, reducing insulin sensitivity and therefore may aid in preventing diabetes. It may reduce LDL cholesterol, blood triglycerides, inflammatory markers, which are all risk factors for heart disease. It can also improve immune function as it facilitates the release of the hormones that stimulate the immune system which is released by both fasting and sleeping. Last but not least, it can improve digestion by giving the gut a break from constantly processing food allowing it to heal continuing through the digestive tract to the intestines. It can be done daily, once a week or a few times a month. There are several variations of It that range in length of fasting, times of the day and calorie intake:
- Time-Restricted Feeding or 16/8 or The 8 Hour Window – Good for starters and is done by creating a 16-hour fasting window and only eating within a designated time frame. For example, meals are eaten from 8am to 4pm, with fasting during the remaining hours of the day. Alternatively, eating can occur between the hours of 12 pm and 8 pm.
- The 12 Hour Fasting –Another great starter fast that involves not eating for 12 hours which is easily done if 8 hours are occupied by sleeping. For example: eat breakfast at 7am a regular lunch and finish dinner by 7pm. The rest is history!
- Alternate-Day Fasting (ADF) or 24 Hour Fasting – This consists of rotating between days of regular eating with days that consist of one meal proving about 25% of daily calories. For example, during 2 non-consecutive evenings per week, finish dinner and do not eat again until dinner the next day.
- Whole-Day Fasting or 5:2 Plan –Similar to the ADF, fast 1-2 days per week or up to 25% of daily calorie needs, with no food restriction on the other days. For example, eat regularly 5 days of the week and eat a 400-500 calorie diet the other two days of the week.
Special consideration should be given to women who are pregnant or breastfeeding or possibly trying to conceive unless it is for the purposes of shedding excess weight prior to conception. Women who have amenorrhea should also caution the use of IF as this may further disrupt their cycle. Diabetics are not suitable candidates due to insulin insensitivity. Adolescents in growth stage may not benefit from It as not to disrupt full development. This may not be suitable for those who are underweight or struggle with eating disorders. Lastly, anyone on medications should also take precaution as food may be required with meds and may also affect insulin.
2. https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC5674160/#bib20
3. https://www.sciencedirect.com/science/article/pii/ S193152441400200X
4. https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC5674160/#bib20