Is fasting healthy?10 years ago | Nutrition
By pH health care professionals
People fast for all kinds of reasons. Sometimes it’s religious, other times it’s to lose weight or to rid the body of toxins. And there are different types of fasts too. Some people don’t eat or drink anything for a period of time, while others partake in a limited amount of food or drink, like only juice or teas. There’s also intermittent fasting, which is kind of like interval training your diet – you go through intervals of fasting and not fasting, on and off. One common approach to intermittent fasting is following a pattern of eating only during an eight-hour window of the day, and fasting the rest of the day.
But is it healthy to go without eating for a period of time? Let’s be proactive and examine the potential benefits and risks.
Potential health benefits:
Many of the potential benefits require further scientific research to confirm. Many studies have focused on animal subjects and found positive results, but this does not guarantee that humans would experience the same benefits. It does, however, indicate a need to explore the idea with further studies.
- A short fast may recharge your immune system. According to a study published June 2014 in Cell Stem Cell, cycles of fasting (no food for two to four days at a time) not only protected against immune system damage, but also induce immune system regeneration, awakening stem cells into a state of renewal (read more here).
- Alternate day fasting may help with weight loss. A study on non-obese people published in American Society for Clinical Nutrition found that participants did lose weight and fat mass by fasting on alternating days. However, researchers noted that hunger did not decrease over time on fasting days, suggesting this diet would not be feasible long-term. Many weight loss experts agree, noting that fasting can backfire and lead to overindulging. Alternate-day fasting has shown some promise in animal trials and limited human trials, but more studies on humans are needed.
- Intermittent fasting may improve risk factors for coronary artery disease and stroke. A study published in the Journal of Nutritional Biochemistry found that intermittent fasting (reducing meal frequency) and calorie restriction extended lifespan and increased resistance to age-related diseases in rodents and monkeys and improved the health of overweight humans. Fasting and calorie restriction enhanced cardiovascular and brain function and improved risk factors like blood pressure and insulin sensitivity. Some studies have also noted positive changes in blood lipids.
- Fasting before or after chemotherapy may offer benefits. More research in humans is needed here. A 2012 study looked at rodents with cancer who were given chemotherapy after 48-60 hours of fasting (having only water) and found that they had better results from the chemotherapy than the rodents who ate before treatment. And another report found that 10 patients who fasted before (and some after) chemotherapy reported less bothersome fatigue, weakness and intestinal side effects. The American Cancer Society reviewed existing evidence in a 2012 article and found that there is not enough to support using fasting for cancer treatment at this time, but that more human studies are underway.
Potential health risks:
- Immediate side effects. Short-term side effects may include headaches, dizziness, lightheadedness, fatigue, low blood pressure and abnormal heart rhythms.
- Dehydration. Dry fasting (no fluid intake) can quickly result in dehydration and death over a period of days, with the length of time varying by person and situation.
- Malnourishment. When that happens, your body may be prompted to go on a survival mode, where it would try to preserve the remaining calories and fats that it has. Consequently, the body’s metabolic rate would decrease, which means that you would be less energetic than you usually are.
- Gout and gallstones. Fasting can raise the risk of an attack in people with gout and worsen gallstone symptoms, according to the American Cancer Society.
Overall, the health benefits and risks depend on the type and length of fast. Generally, it appears that shorter fasts (like intermittent fasts) carry the most benefit with the least risk. You can try this by eating your food earlier in the day so your body has a period of fasting before bed and through the night.
Note that it is always best to check with your doctor before trying any type of fast, especially if you have diabetes or if you’re hypoglycemic. Fasting is not a good idea for pregnant or breast-feeding women.
Enjoy Your Healthy Life!
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