The festival season was just around the corner when the message came. My younger sister just forwarded a message from a senior colleague about the pros and cons of intermittent fasting (IF). I was rather intrigued by his knowledge and confidence in the proclaimed benefits of this option but a worrisome thought lingered inside me. What if people are unaware of the real dangers of these non-conventional eating patterns? May be its time to write a piece on this new fad. Here we go.
- What do we mean by intermittent fasting?
Intermittent fasting is a common word for any type of food restriction that we undertake on a regular basis. The appropriate scientific term would be intermittent energy restriction (IER). The alternate of this intermittent fasting is continuous energy restriction (CER). Typically, most dieting restrictions were under this category till recently. Here we try to restrict our energy intake by 25 to 50%. There is calorie restriction on all days for CER in contrast to IER. Basically, one (CER) does it constantly every day and other (IER) restricts it more on some days. Current debates focus on IER versus CER, we will come to that later in this article. IF is just a modified eating pattern and not a diet plan as is commonly believed.
2. What are the types of Intermittent fasting?
It could be basically grouped into three types. a. Alternate day fasting (ADF) where we eat nothing on alternate days and eat normally on the other days. There is no restriction on the eating days. This is the most stringent of IF regimen. b. Alternate day energy restriction (ADER) where we eat only 30 to 50% of our required energy/calorie intake on certain days and eat normally for the rest of the week. This is the most popular among the IF regimens. More popular one is 5:2 where we eat normally for 5 days and on the fast mode for 2 days every week. During fast days, we eat only 30 to 50% of the required calories. c. Time restricted feeding (TRF) where we fast for a fixed period of time every day and eat only during the remaining time. Popular ones are the 18:6 where we fast for 18 hours of the day and eat only during the remaining period of 6 hours. You can personally decide when to eat but preferably, not during night time.
3. What are the reasons behind people adopting intermittent fasting modes?
Most people jump into the IF wagon to reduce body weight and belly fat. Some others want to control diabetes, heart disease and hypertension. A minority jump into this for reasons that range from cardiovascular health, longevity, reducing inflammation and even staying away from Alzheimer’s disease and cancer.
4. What happens when we do intermittent fasting?
Whenever we fast, the body adapts to the change. The regular fuel of the body is glucose which comes primarily from carbohydrates. When we fast, this deficit of glucose is managed by releasing the glucose stored in our body in the form of glycogen. After about 8 hours of fasting, the stored reserves burn out and the body needs to make glucose from other sources. The body enters the fasting mode and the process called gluconeogenesis sets in. This process produces glucose from our body fat reserves. This is basically what we call fat burn. On prolonged fasting, even these resources will get depleted and the body might move into starvation mode where muscle cells will be broken to supply glucose. It takes days or weeks of starvation to reach this phase. On intermittent fasting, we only reach the fasting mode where glucose is primarily made from our fat reserves.
5. What are the proven benefits of intermittent fasting?
Several studies have proven that intermittent fasting as well as continuous calorie restriction, both has beneficial effects on several risk factors. Both options can reduce body weight. Typical weight loss seen ranges from 5 to 10 kg for a four-month period on both IER and CER. Body fat as well as waist circumference can drop reasonably well during this period. There are studies that have shown reductions in blood pressure, insulin resistance, total cholesterol, LDL and triglycerides while on IER or CER. Studies on diabetics have shown reductions in HbA1C (a measure of good diabetic control) which suggests improvement. The other listed benefits of reducing inflammation, longevity and prevention of cancer are from animal studies and are difficult to be replicated in human trials.
6. Who should stay away from intermittent fasting?
There is no real data coming from children, adolescents, pregnant women and lactating mothers regarding intermittent fasting. These individuals should stay away from IF. In the case of chronic illnesses like diabetes, heart diseases, kidney diseases, cancers and other chronic inflammatory conditions, the best option is to discuss with your physician before you jump into IF. People on medications should definitely consult their physician before practicing any of the calorie restrictions. Intermittent fasting has a negative effect on the reproductive health and is not advisable for women with fertility issues. Elderly individuals (those above 70) should preferably stay away from intermittent fasting.
7. What are the side effects of intermittent fasting?
At the start of any IF regimen, you will feel sever hunger pains. You may feel tired and might even be at risk of hypoglycaemia and dehydration. It may be difficult to concentrate during the early days. There is a risk of binge eating on the non-fasting days as a response to fasting. Eating more at night could impair the sleep quality and may also result in aggravation of acid reflux in susceptible individuals. The long-term side effects are yet unknown. Be careful not to mix alcohol with fasting as all side effects mentioned above can be aggravated by this combo.
8. Will You lose muscle mass while on intermittent fasting?
There is every possibility for losing muscle mass while on intermittent fasting or any other type of calorie restriction. The only way to prevent or slow down the process of muscle wasting is to combine it with exercise and eat more protein on non-fast days. A physician consult is required if you plan to exercise during the fasting days.
9. Is it possible for people to be adherent to intermittent fasting regimens?
Compliance is a serious issue when it comes to any type of dietary restriction, be it intermittent or continuous calorie restriction. All IER regimens have significant drop outs but the compliance is still better than CER. Typically, one in six on IER lose interest and drop out in the long term but it’s still better than the one in four that dropout out from CER. Figures tells us that it’s easier to adhere to IER than to CER.
10. What is the final message?
Both forms of fasting whether it is continuous or intermittent are good for several reasons including reducing body weight, losing body fat, improving insulin sensitivity, improving blood pressure and reducing triglycerides. In the absence of contra-indications, we can adopt the one we can sustain. We need to be mindful of what we eat on the non-fast days, its preferable to go on a predominantly plant-based diet enriched with protein. Mind you, binging on non-fast days will spoil all your efforts and its better if you eat less on non-fast days by 10 to 20%. For beginners, its better to start with a time restricted feeding pattern (16:8 or 18:6) before moving on to a 5:2 or 3:4 IER plan. Regimens that propose complete fasting (no food at all on fasting days) are not safe and it is better to avoid them. Always consult your family physician before adopting any calorie restriction to be on the safe side.
Happy Fasting for all readers.
Dr. Manu Raj @ DocM Health.
