Intermittent fasting (IF) has become one of the world’s most popular health and fitness trends over time. It involves planning your meals in a way that there are interchanging periods of fasting and eating.
Intermittent fasting cannot be considered as a diet. It is a pattern of eating. It particularly involves “when you should eat, not which foods to eat”. In other words, it’s a way of scheduling your mealtime not your meal content.
Types of intermittent fasting
While there are several methods of intermittent fasting, the most common methods involve:
1. Daily 16-hours fasting or 16:8 plan[1]: The 16:8 plan is the most commonly adopted method and involves skipping your breakfast and restricting your daily eating period to 8 hours, such as 12-8 p.m followed by fasting for 16 hours.
2. Fasting for 24 hours, twice a week: This means fasting for a whole day i.e. for 24 hours twice a week and the other 5 days managing a balanced calorie meals.
3. The 5:2 plan: In this method, you consume only 500-600 kcal on two non-consecutive days of the week, but eat normally the other 5 days.
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People consider intermittent fasting to be fairly easy. It’s true that the body gradually gets used to not eating for an extended period of time, but before you start following it, let’s seek answers to some of the questions that you might have about intermittent fasting.
Answering some most common questions on Intermittent Fasting
Q.1. How does it help in weight loss/fat loss?
In intermittent fasting, when you fast, your insulin levels reduce significantly and human growth hormones increase drastically. This process signals your body to start producing energy by burning stored fat to make up for the unavailability of food. The lack of food means that your body is not getting the carbohydrates it needs to convert to sugar and energy. As a result, the blood glucose levels fall and your body starts pulling out the glucose stored in your body to get enough energy, thereby burning the extra fat.
Simply put, intermittent fasting helps to lose excess weight and fat by restricting the overall amount of calories you eat in a day. But remember, if you start eating massive amounts of unhealthy foods during your eating window, you will undo the fat-burning process that happens during your fasting period.
Q.2. How much weight can you lose with intermittent fasting?
According to studies, about 3-8% weight can be reduced over 3-24 weeks with intermittent fasting. It can produce a weight loss at the rate of approximately 0.25-0.75 kg/week.[8]
Q.3. Can I drink during intermittent fasting?
Anything less than 50 kcal during fasting period can be consumed. Drinking tea or coffee with a splash of milk without sugar can be considered. Drinking water is strongly recommended to keep the body hydrated.
Q.4. What can I eat while practicing intermittent fasting?
To make sure that you don’t lose out on essential nutrients, keep these 5 things in mind.
1. Balance each meal with a variety of healthy foods.
2. Include high fiber foods such as nuts, fruits, vegetables specially greens, whole grains and pulses, etc. in your meals.
3. Choose from healthy fats such as olive oil, avocado oil, mustard oil, coconut oil.
4. Include good sources of proteins like lean meats, poultry, fish, legumes, pulses, soy, eggs, nuts, seeds.
5. Drink plenty of water to stay hydrated.
Q.5. Who should not practice intermittent fasting?
Intermittent fasting should be strictly avoided by women who are pregnant or are breastfeeding. Other than this, anyone below the age of 18 should avoid practicing this regimen. If you wish to follow intermittent fasting, it is wise to do so under a doctor’s supervision, especially if you’re underweight or have eating disorders like anorexia.
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Q.6. Does intermittent fasting have any side effects too?
Here are the side effects of intermittent fasting:
– Excessive diet consciousness: Being on a restrictive diet can make you spend an excessive amount of time thinking about the right quantity and quality of food. This overthinking on “correct” or “healthful” eating can cause an eating disorder known as “orthorexia” which can be detrimental to your overall well-being.
– Frequent hypoglycemic episodes: Intermittent fasting can cause low blood sugar levels (hypoglycemia), especially in people with diabetes and thyroid. Having frequent nausea, headache or dizziness while practicing intermittent fasting is a red flag for you. Therefore, intermittent fasting should be followed under doctor/dietitian’s supervision only.
– Dehydration: People may forget drinking water during the 16-hour long period of fasting and being without water for 16 hours can disturb your digestion and cause constipation.
Q.7. Apart from weight loss, does intermittent fasting have any other benefits too?
Intermittent fasting may also help:
– Reduce insulin resistance: Intermittent fasting can reduce insulin resistance, lowering blood sugar by 3-6% and fasting insulin by 20-31%, which should help protect against type 2 diabetes.[4]
– Reduce inflammation: Some studies support its effect on the reduction of inflammation markers, a key driver of many chronic diseases.[5]
– Improve heart health: Intermittent fasting can reduce risk factors for heart disease i.e. LDL cholesterol, inflammation markers, blood triglycerides and blood sugar.[6]
– Support brain health: Intermittent fasting increases the brain hormone and aids in the growth of new nerve cells. It is also helpful in Alzheimer’s disease.[7]
Word of caution for people having diabetes or taking medications
Though several studies have supported intermittent fasting as an effective way for weight loss, fat loss and waist circumference reduction[2] [3], it is important to note that most of these studies are new and of short span.
Intermittent fasting may pose a potential danger to people taking medications as doses may need to be adapted accordingly. Another danger of following intermittent fasting could be for people with diabetes who may experience frequent onset of hypoglycemia, especially during nights. Therefore, it is always recommended to discuss with your doctor before starting this type of diet regimen.
(The article is reviewed by Dr. Swati Mishra, Medical Editor)
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References:
1. Gabel, K., et al. (2018). Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. 1 Jan. 2018 : 345 – 353. https://content.iospress.com/articles/nutrition-and-healthy-aging/nha170036
2. A Johnstone. Fasting for weight loss: an effective strategy or latest dieting trend? Int J Obes (Lond). 2015 May;39(5):727-33. https://doi.org/10.1038/ijo.2014.214
3. Leonie K Heilbronn, Steven R Smith, Corby K Martin, et al. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr. 2005 Jan;81(1):69-73. https://doi.org/10.1093/ajcn/81.1.69
4. Adrienne R Barnosky, Kristin K Hoddy, Terry G Unterman, et al. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Transl Res. 2014 Oct;164(4):302-11. https://doi.org/10.1016/j.trsl.2014.05.013
5. James B. Johnson, Warren Summer, Roy G. Cutler, et al. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radic Biol Med. 2007 Mar 1; 42(5): 665–674. https://doi.org/10.1016/j.freeradbiomed.2006.12.005
6. Krista A Varady, Surabhi Bhutani, Emily C Church, et al. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. Am J Clin Nutr. 2009 Nov;90(5):1138-43. https://doi.org/10.3945/ajcn.2009.28380
7. Veerendra Kumar Madala Halagappa, Zhihong Guo, Michelle Pearson, et al. Intermittent fasting and caloric restriction ameliorate age-related behavioral deficits in the triple-transgenic mouse model of Alzheimer’s disease. Neurobiol Dis. 2007 Apr;26(1):212-20. https://doi.org/10.1016/j.nbd.2006.12.019
8. Adrienne R Barnosky, Kristin K Hoddy, Terry G Unterman, et al. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Transl Res. 2014 Oct;164(4):302-11. https://doi.org/10.1016/j.trsl.2014.05.013