During prehistoric times, humans were already used to going for long periods without sustenance because food was not readily available. They had to hunt animal sources of food and gather plant sources of food. They were technically fasting during those times when they had to look for food.

In ancient times, fasting had already been practiced worldwide, primarily as part of spiritual practices and medical purposes that slowly evolved into a lifestyle for illness prevention, as well as weight management.

Fasting, however, is not just for losing weight. The benefits go beyond just the aesthetics. What exactly happens when the body goes on no food intake for hours or days? What does science have to say about the benefits of fasting?

A randomized controlled trial on intermittent fasting plus early-time restricted eating versus calorie restriction, and standard care in adults at risk of type 2 diabetes was published in 2023. It was conducted by Xiao Tong Teong and colleagues. Their study on 209 adult participants showed that incorporating advice for meal timing with prolonged fasting had a positive impact on postprandial glucose metabolism among adults who are at risk of developing type 2 diabetes.

Simply put, there is an improvement in the blood glucose or sugar level of the participants after meals. Individuals who have insulin resistance have higher blood glucose levels after meals because the cells are resistant to the hormone insulin. Insulin functions as the carrier or vehicle of glucose so that sugar can efficiently enter the cells to be utilized as energy. In the case of insulin resistance, a risk factor for developing type 2 diabetes, glucose remains in the blood, causing blood values to elevate abnormally.

An individual taking insulin shots or oral anti-diabetic medications must not attempt to undergo any fasting method unless approved by his or her physician and guided by a registered nutritionist or dietitian.

Another benefit of fasting is fighting or decreasing inflammation in the body. Acute inflammation, when we have injuries or infection, is a normal response of the immune system that is protective in nature. Chronic or long-term inflammation, which is characterized by a slow immune response, allowing the pro-inflammatory cells in the body to attack healthy tissues for a long period of time, is harmful to the body. It is also related to illnesses such as cancer, diabetes, heart disease, autoimmune diseases, and more. It also affects sleep, energy level, the function of the digestive system, weight, and even brain function, including mood.

In a systematic review and meta-analysis of 18 randomized controlled trials in 2020, Xiaoli Wang and colleagues thoroughly reviewed the effects of intermittent fasting diets on plasma concentrations of inflammatory biomarkers, specifically CRP or C-reactive protein concentrations. C-reactive protein is produced in the liver as a response to the presence of inflammation in the body. Elevated CRP levels are associated with infections that can be caused by viruses or bacteria, a major injury, heart attack or heart disease, obesity, pancreatitis, bronchitis, and systemic inflammation found in medical conditions such as autoimmune diseases, rheumatoid arthritis, and systemic lupus erythematosus or SLE.

Xiaoli Wang’s team of researchers concluded that their meta-analysis demonstrated a reduction in the C-reactive protein concentrations after eight weeks of intermittent fasting, specifically, among overweight and obese individuals. Reduction in the concentration of the pro-inflammatory marker C-reactive protein not only reduces chronic inflammation but also decreases the risk of developing chronic illnesses.

Overweight and obesity are a global burden due to the obesogenic environment that has been caused by ultra-processing of food, a highly stressful society, and advancement in technology that led to a more sedentary lifestyle. Fasting will benefit individuals who are overweight and obese beyond weight loss.

In another systematic review and meta-analysis of seven randomized controlled trials conducted on 269 participants by Jihyun Park and colleagues on the effect of alternate-day fasting on obesity and cardiometabolic risk in 2020, they concluded that alternate-day fasting effectively lowers body weight and Body Mass Index (BMI). The more interesting thing is that it did not lower weight and BMI through muscle mass loss or water loss, which is what usually happens when one undergoes a weight loss program that is not properly done. Alternate-day fasting effectively lowered the body fat mass and total cholesterol. Thus, decreasing the cardiometabolic risk. Cardiometabolic risk refers to a group of factors that significantly increase the risk of developing heart disease, stroke, and type 2 diabetes mellitus. The risk factors include elevated cholesterol, abdominal fat, high blood pressure, high blood sugar, and triglycerides.

Oftentimes, we think that we are depriving ourselves when we refrain from eating, but it is beneficial to our health. We allow our bodies to rest and recover from the burden of digesting and metabolizing food. We promote the utilization of stored fat as energy, as well as give the body an opportunity to produce new healthy stem cells that are healthy. Nutrient deprivation during fasting triggers autophagy. It is the body’s natural way of cleaning up and detoxifying by causing cells to break down and recycle to promote cellular repair.

Should you fast at the start of the New Year? If you are overweight, obese, have insulin resistance, high cholesterol, and are experiencing symptoms like brain fog, fatigue, and mood alterations, you should consider fasting. To know what type of fasting will suit your current condition, it is best to consult a registered nutritionist or dietitian for proper guidance. It is also best to fast according to your circadian rhythm or body clock instead of fasting the entire day and eating late at night.

Happy, healthy New Year!