According to a Harvard Health Publication, intermittent fasting is based on the practice of severely restricting calories during certain hours or days of the week in hopes to slow the body’s metabolism and decrease appetite. This diet trend claims to burn fat faster than most diets, reduce overall inflammation and reduce the risks of heart disease. There are several ways to intermittent fast, such as daily fasting for 12-14 hours (or, simply put, skipping breakfast), the 5:2 method where the user eats normally for five days and restricts their consumption to 500-600 calories for two days, or alternating “fast” days with “feast” days where the user consumes a quarter or less of their calorie requirements some days and eats whatever they choose on other days.
While there have been studies done on this dieting pattern, most studies have been short lived, contain a small number of participants, or studied on overweight mice instead of overweight humans. Dr. Frank Hu, chair of the department of nutrition at the Harvard T.H. Chan School of Public Health, explains that there are many downfalls that people may face when starting this diet. Most importantly is the drop-out rate, which accounted for 38% in a recent study done with 100 participants. When faced with a severe restriction in calorie consumption, many people find themselves wanting to reward themselves for doing hard work or purging after a fast. This act almost completely negates the benefits gained in the completed fasting days.
Effects of intermittent fasting has been largely studied on a cellular level or in animals. Therefore, the true effects on humans is not yet known. Early results from a small clinical trial published by BMJ Journals has reported that intermittent fasting can help stabilize glucose control, as well as aid in lowering blood pressure and reducing inflammation. However, it is not clear whether these results are directly related to intermittent fasting or the weight loss that comes along with fasting.
Researchers have noted some drawbacks that were found among intermittent fasting participants, such as disrupted sleep, decreased alertness, higher LDL levels, and even pancreatic damage. LDL is also known as “bad cholesterol”, and a recent JAMA study showed that after twelve months, participants who followed fasting guidelines had significantly higher LDL levels than those who practiced daily calorie restrictions. A Brazilian study done in 2018 showed that overall weight loss was achieved through intermittent fasting in rats, however there was also muscle loss and belly fat gain. The pancreas also showed changes in insulin secretion and pancreatic islet metabolism, which may be indicative of increasing the risk of diabetes. After three months of intermittent fasting, the rats also showed insulin resistance and increased insulin secretion, both leading to compromised glucose balances.
Intermittent fasting is a popular diet trend based on the premise of severe calorie restriction to promote weight loss, decrease high blood pressure and aid in balancing blood sugar levels. This technique has been around for centuries and is involved in many religious practices, however there is not enough evidence to deem this as an entirely beneficial form of dieting. Recent studies have been showing more cons than pros, and medical doctors and dieticians are trying to promote patients to consume healthy foods as opposed to severe calorie restrictions to remove excess body weight.
Medicine vs. Myth 