Obesity is emerging as a global problem. According to the data from 2017 to 2018, about 42.5 percent of adults aged 20 years and older are obese. When overweight and obese adults aged 20 years and older are grouped together, the figure is even more alarming. An estimated 73.6 percent of the adults aged 20 years and older are overweight (including obese individuals) as revealed by the 2017 to 2018 data. Obesity increases the risk of obesity-related health conditions, such as diabetes, high blood pressure, stroke, heart attacks and certain cancers. Hence, staying fit is being increasingly realized as a prime concern. Over the last few years, various diets and exercise regimens are gaining popularity as ways to manage obesity and lifestyle diseases. Intermittent fasting is one of the popular dietary regimens.
What is intermittent fasting?
Weight management tips have primarily been about “what to eat.” Intermittent fasting is one of the dietary practices that emphasize “when to eat.” Intermittent fasting focuses on the pattern of eating that involves eating in a specific time window and fasting in the remaining period of the day. Because the eating periods are interspersed with fasting periods, this dietary regimen is called intermittent fasting. The fasting period includes nighttime when you sleep because you don’t eat or drink anything during this time. During the fasting window of the day, you need to strictly abstain from consuming (eating or drinking) anything that has calories. It is suggested that this caloric abstinence trains your body to use stored fat as energy. Non-caloric drinks (such as water) and beverages (including diet sodas and unsweetened black coffee or tea) are allowed during the fasting period.
How do you do intermittent fasting?
There are different ways you can do intermittent fasting, ensuring that you strictly consume no calories during the fasting phase. Some of the approaches for intermittent fasting are
- The 16/8 method: It is a popular form of intermittent fasting. The 16/8 method is also called early time-restricted feeding or eTRF. In this method, you keep an eight-hour eating window with 16 hours of fasting. This is generally safer and more convenient for most people because they already fast during sleep and extend the overnight fast by skipping breakfast and not eating until lunch. One common practice is eating only between 12 p.m. and 8 p.m. and fasting from 8 p.m. to 12 p.m. the next day. Based on your schedule and preferences, you may keep the eating window between 11 a.m. to 7 p.m. or 10 a.m. to 6 p.m. and fast for the rest of the time (16 hours). You may follow this method as often as you wish. Some people do the 16/8 fasting once or twice a week.
- The 14/10 method: This method is similar to the 16/8 method, the difference being the eating window. In the 14/10 method, you have a 10-hour eating window. For example you may eat between 10 a.m. and 8 p.m. and fast for the next 14 hours.
- Alternate day fasting: As the name suggests, this method involves the intake of a few calories (500 calories or just 25 percent of your normal intake) on one day alternating with a regular healthy diet on the next day. Some people may practice the stricter version where they do not consume any calories on the fasting day. In one variation (called Eat Stop Eat method), complete fasting is done for 24 hours (such as breakfast to breakfast or lunch to lunch) followed by normal eating the next day. Generally, it is done once or twice a week. This may be harsh for some people and it is not advisable to follow this method unless you discuss it with your healthcare provider. This form of fasting may cause side effects, such as fatigue, irritability, hunger and headaches.
- The 5:2 method: It is also called the twice a week method. It involves limiting the calorie intake to 500 for two days a week and consuming a healthy normal diet the rest of the week. You may choose any two days in a week to eat 500-calories a day, but ensure you have a non-fasting day in between. You may include a lot of fiber and protein (while ensuring you do not exceed the 500-calorie limit) in the form of salads so that you stay full on the fasting days. Most people have two meals on the fasting days, which could be 250 calories each or one meal of 200 calories and another of 300 calories.
Is intermittent fasting safe?
Intermittent fasting may not be safe for everyone. You must consult your doctor before you try intermittent fasting. Intermittent fasting may not be advisable for you if you
- Are pregnant or breastfeeding.
- Are 18 years old or younger.
- Have certain health conditions, especially diabetes, kidney stones and gastroesophageal reflux disease (GERD).
- Are on any medications (including insulin).
- Have a history of eating disorders.
Intermittent fasting may have side effects, such as nausea, headaches, low energy, hunger and lack of sleep, which generally subside on their own within a month. They may, however, be more problematic in some people than others. If you are on glucose-lowering medications, you may get dangerously low sugar levels during the fasting window. Remember that intermittent fasting is not a magical therapy for weight loss. You need to consume fewer calories than you burn during the day to lose weight. Though intermittent fasting has been shown to have various benefits (including improvement in arthritis, blood cholesterol and diabetes), it is always better to consult a doctor before embarking on a new dietary regimen.
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Cleveland Clinic: "Intermittent Fasting: 4 Different Types Explained." https://health.clevelandclinic.org/intermittent-fasting-4-different-types-explained/