Why should we fast?

Intermittent fasting has gained a lot of popularity recently. There are more and more research and data on the benefits of fasting besides weight loss. Some potential benefits are:

Longer life

Sharper mind

Improved metabolic health - lower blood sugar, cholesterol, blood pressure

Decreased inflammation

Reduced chance of chronic disease - diabetes, hypertension

Cancer prevention

Anti-aging!

There are published articles that showed intermittent fasting can prolong life and improve concentration. More data on the benefits of intermittent fasting are emerging. However, some of the research are on mice. I will go through them on subsequent blogs.

During a fast, meaning not eating for at least 12 hours, the body starts to use stored reserve for energy. Once the body finishes burning the calories from the food intake, the pancreas will release glucagon which signals the liver to convert the stored glycogen into glucose. When the glycogen is depleted, the body will turn to the stored fat as a source of energy through a process that a lot of people will also recognize - ketosis. The time needed to get to this ketotic state is different for everyone, some as short as 12 hours, others may need 48 hours. The initial source of fat used in ketosis is the metabolically active fat - the visceral fat. So, the first fat to be burned when fasting is the truncal visceral fat that surrounds the internal organs. Reducing visceral fat is desirable because it is this metabolically active fat that leads to diabetes, hypertension, hypercholesterolemia, and ultimately cardiovascular disease. Besides fat, muscle is the other energy reserve. However, muscle mass is important to maintain and even grow!

It is important to clarify this fat burning point. In weight loss, the fat in the face and neck area is noticeably reduced first, and if the weight loss is too rapid, it can lead to the so called Ozempic face when the skin of the face and neck sags. In ketosis, the body burns visceral fat and is using up the stored internal fat for energy. Eventually, if one continues to have ketosis, there will be weight loss. Ideally, if we get into ketosis, replenish our calories appropriately, plus the proper exercise, we can change our body composition and get rid of the visceral fat without loosing too much fat on the face and neck!

There are many ways of intermittent fasting. The easiest and most commonly adopted intermittent fasting diet is the 16:8, fasting for 16 hours and eating for 8 hours of the day. This diet is easy to adhere to and does not require additional vitamins or macronutrients supplement. However, the weight loss may not be significant and the body may not really get to the “fasting” state, to utilize the stored energy reserve. Staying active and exercising is one way to ensure the body uses the reserve. In fact, some studies showed that exercising during the fast will burn more fat.

The other ways of intermittent fasting are more drastic and involve fasting for at least 24 hours. Fasting for prolonged period of time is gaining popularity but more research and data are definitely needed. Some of the more common ones are:

5:2 diet is fasting or eating <500 calories for 24 hours, 2 days of the week. Then eat normally for the other 5 days.

Alternate day fasting is eating for a day, then either completely fast or eat <500 calories the next day.

It is important to continue eating a healthy, balanced meal, preferably the Mediterranean diet rich in grains, proteins and vegetables. Binge eating or eating indiscriminately will defeat the purpose of the fast.

Personally, I feel the difference 15:9 intermittent fasting diet has done for me. My goal is to reduce my body percentage fat, particularly the visceral fat and to build muscle. I am eating more proteins, reducing carbs, especially fine carbs and sucrose, and doing weight or resistant training daily. Now that I am comfortable with fasting for 15 hours, I am moving on to 16:8.

*Even though intermittent fasting is relatively safe, it may not be suitable for everyone. Do consult with a physician whether this would be recommended for you.