Shahar Madjar, MD

I have written here before about intermittent fasting. The idea is simple: alternate periods of eating and fasting. The fasting periods vary according to different regimens with periods of fasting ranging from several hours to two days at a time and even longer. A common intermittent fasting regimen is 8:16. You eat for 8 hours, say from noon to 8 PM, and fast for the remaining hours of the day.

Scientists and doctors who recommend intermittent fasting cite its beneficial effect on a variety of health outcomes including weight loss. Intermittent fasting may work in two ways: by reducing the total number of calories consumed, or by tapping the body’s fat stores for energy faster and more efficiently than in a plain calorie-restricting diet.

Intermittent fasting has gained much popularity. Many doctors recommend the diet to their patients and individuals who have tried intermittent fasting tend to swear by it. All of these people were rightfully shocked by a recent study presented at the latest American Heart Association meeting in Chicago (March 2024).

The study, conducted by Victor Wenze Zhong, Ph.D., from the Shanghai Jiao Tong University School of Medicine in Shanghai, China, included approximately 20,000 U.S. adults with an average age of 49 years. The researchers followed the participants in the study for 8 to 17 years. The study concluded that participants who followed an 8-hour time-restricted eating schedule (eating for 8 hours and fasting for 16 hours a day) had a 91% higher risk of death from cardiovascular disease (diseases of the heart and blood vessels such as heart attacks and strokes).

These results seem to contradict prior knowledge. One example is an extensive review that was published in The Lancet (April 2024) in which the researchers analyzed the results of 23 previously published meta-analyses (studies that combine, analyze, and summarize prior research studies). They found that intermittent fasting had beneficial effects on waist circumference, fat mass, insulin levels at the time of fasting, LDL-cholesterol (bad cholesterol) and total cholesterol. The authors concluded that compared to continuous energy-restriction diet or to no-intervention at all, intermittent fasting may have beneficial effects on a range of health outcomes for adults who are overweight or obese.

To summarize the opposing views, Dr. Victor Wenze Zhong claims that intermittent fasting results in higher risk of death while The Lancet’s review provides evidence for the beneficial effects of intermittent fasting. How can one reconcile these seemingly contradicting messages? Should you embark on intermittent fasting or should you, for fear of early death, entirely avoid it?

One possibility is that the results presented in the newer study by Dr. Victor Wenze Zhong’s study are skewed. First, the study relied on diet information reported by the participants and there is always a chance that the participants didn’t recall the information accurately. Additionally, the analysis, as presented in the scientific meeting, didn’t include factors other than the daily duration of food consumption. Such factors might have affected the participants’ general health and their risk of death. If the researchers didn’t consider these factors appropriately, inaccurate conclusion might have been reached.

Another possibility is that the opposing conclusions presented in the two studies are both true. It is possible that intermittent fasting may result in short-term health benefits, but also in long-term adverse events. After all, Dr. Victor Wenze Zhong’s study is focused on a time frame much longer than The Lancet’s review (8-17 years in Dr. Victor Wenze Zhong’s study, and up to 56 weeks in The Lancet’s study).

Which one of the possibilities is true?

Last week, in the middle of my workday, in between seeing patients, I stepped out of my office, put on a pair of eclipse glasses, looked up to the sky, and witnessed the solar eclipse. I wasn’t standing in the path of totality but the event was nevertheless impressive. I imagined our ancestors witnessing the same phenomenon–total darkness in midday–which contradicted all they had known. It would take many generations to correctly describe total solar eclipse (by the astronomer Johannes Kepler in 1605).

Whether it’s intermittent fasting or solar eclipse, when faced with information contradictory to what you believe you know, patience is crucial. To gain new insights, to truly understand, it pays to wait. As the saying goes, Time will Tell.

EDITOR’S NOTE: Shahar Madjar, MD, MBA, is a urologist and an author. He practices at Schoolcraft Memorial Hospital in Manistique, and in Baraga County Memorial Hospital in L’Anse. Find his books on Amazon or contact him at smadjar@yahoo.com.