Fasting possesses great power. If practiced with the right intention, it makes one a friend of God.
—QUINTUS TERTULLIAN (AD 160–220)
EARLY CHURCH LEADER AND AUTHOR1
SO FAR I HAVE EXAMINED GENERAL SCIENTIFIC information regarding fasting without specific mention of religion. Still, it is worth examining whether fasting has any beneficial health effects for those who fast for spiritual purposes. Although there are many types of fasting within Christendom, in this chapter I will focus on those for which published, peer-reviewed scientific studies exist. For the purpose of this discussion, I will group them into two major categories: the Daniel fast and Lenten (and other Greek Orthodox) fasts.
The Daniel fast
The Daniel fast is a common practice within many Christian circles. The length of such fasts can vary. This type is named after the story of two fasts followed by the Old Testament prophet Daniel (Dan. 1:8–14; 10:2–3). In the first—and most familiar to Christians—Daniel requested that he and his three Hebrew friends be provided only vegetables to eat and water to drink for ten days. They chose this strict diet instead of partaking of (and defiling themselves with) the royal food and wine provided at the palace. Here is a short account of this event from the Bible:
Daniel then said to the guard whom the chief official had appointed over Daniel, Hananiah, Mishael and Azariah, “Please test your servants for ten days: Give us nothing but vegetables to eat and water to drink. Then compare our appearance with that of the young men who eat the royal food, and treat your servants in accordance with what you see.” So he agreed to this and tested them for ten days.
At the end of the ten days they looked healthier and better nourished than any of the young men who ate the royal food. So the guard took away their choice food and the wine they were to drink and gave them vegetables instead.
—DANIEL 1:11–16, NIV
Interestingly at the end of ten days Daniel and his friends “looked healthier and better nourished” than others who ate sumptuous meals provided by the king. Could there be any scientific basis to this observation? Fortunately a few studies have measured specific health markers in people going through the Daniel fast in modern times.
As though encouraged by his initial success, Daniel later reported fasting for twenty-one days during which “I ate no choice food; no meat or wine touched my lips; and I used no lotions at all until the three weeks were over” (Dan. 10:3, NIV).
Connecting both versions, modern observances cover a certain period (usually ten, twenty-one, or forty days) in which a Christian abstains from meat and dairy products and eats only vegetables, fruits, whole grains, nuts, seeds, and oils. The primary purpose is to restrict food intake while focusing on prayer and consecration. In this regard, a Daniel Fast meal resembles a vegetarian diet. However, it is even stricter because it includes avoiding alcohol, coffee, food preservatives, sweeteners, additives, and flavors. Indeed, the Daniel fast is a form of dietary restriction, as opposed to a program of caloric restriction. Bear that in mind as I examine some of its health benefits.
A scientific survey
Dr. Richard Bloomer, director of the Cardiorespiratory/Metabolic Laboratory at The University of Memphis in Tennessee, and his colleagues have published the most studies in this area. They include a 2010 article reporting on the effects of a twenty-one day Daniel fast on metabolic and cardiovascular disease risk factors. Their investigation of health biomarkers included forty-three people (thirteen men and thirty women, 35 ± 1 years; range: 20–62 years) who followed a diet of vegetables, fruits, and nuts. Participants followed detailed guidelines and met periodically with investigators. (It is important to note that these individuals purchased their own foods.)2
On the first day of the fast participants reported to the lab for a physical examination, with investigators drawing blood samples for a thorough screening of biological markers for cardiovascular and metabolic risks. At the end of the fast participants again had blood samples drawn for screening. Before both visits participants followed a twelve-hour fasting routine and did not perform any strenuous physical activity or exercise during the preceding twenty-four to forty-eight hours. Researchers measured an extensive set of mental and physical health variables. They included resting heart rate, blood pressure, blood count, a metabolic panel, a lipid panel, and insulin. Researchers also evaluated a homeostatic model assessment, to measure insulin resistance; and C-reactive protein, to determine inflammation and tendency to develop coronary artery disease.
The first thing the study revealed: the spiritual motivation for fasting significantly improved compliance with the fast. I will discuss this spiritual element shortly, but will note here that fasting with the goal of drawing closer to God in prayer and meditation is a crucial factor in seeing benefits from fasting. For this particular study participants’ compliance rate was 98.7 percent.
The next important revelation came from the fact that all the biological markers measured for cardiovascular and metabolic health risks significantly (P < 0.05) improved among the participants by the end of the study. Specifically they showed marked reductions in total and LDL cholesterol (the bad kind) and systolic and diastolic blood pressure, and important (though not scientifically significant) reductions in insulin, HOMA-IR, and C-reactive protein.3
So, in simple language what does this all mean? A key finding is how this study shows that the Daniel fast can lower the risk of developing heart disease and insulin resistance, the latter directly related to diabetes. Another major highlight is how the Daniel fast helped reduce the level of radicals and reactive oxygen species—chemicals such as malondialdehyde (MDA), hydrogen peroxide (H2O2), and nitrate/nitrite (NOx), which cause oxidative damage to DNA.4 These latter findings were published in a 2011 report. Another benefit that emerged from the latter study involved participants reporting improved mood at the end and expressing the desire to continue this kind of fast on their own.
More to the story
The researchers observed a slight downside, however, that is worth mentioning—namely, a significant reduction in total cholesterol. Now, that is a positive in relation to reducing the risk of clogged arteries; lower LDL (“bad” cholesterol) spells lower risks for the heart. However, because there was a dramatic reduction in total cholesterol, it also means that there was a reduction in HDL, or “good” cholesterol.
To understand why this is important, I need to offer a quick explanation of these two types of cholesterol. While the American Heart Association has a simple, easy-to-follow guide on its website,5 I will summarize. Since cholesterol cannot dissolve in the blood, it needs to be carried to and from body cells by special biological “taxis,” called transporters. In this case there are two kinds of “taxi cabs” available—low-density lipoproteins (LDL) and high-density lipoproteins (HDL). As it turns out, the LDL does a lousy job of carrying cholesterol and instead accumulates in blood vessels, where it forms plaques. These plaques can eventually block arteries and cause a range of serious diseases such as heart attack and stroke. So, it’s a bad thing when there are more of these LDL cholesterols available.
On the other hand, the high-density lipoproteins help in ridding the bloodstream of those bad LDL cholesterols. It is believed that HDL cholesterol carries off the LDL cholesterol to the liver, where the body breaks down LDL and eliminates it from the system. So, a relatively high level of HDL cholesterol is considered good for cardiovascular health. It is therefore important to not only have a low level of LDL, but also a high level of HDL.
This means that the fact that HDL cholesterol was lowered in participants in the Daniel fast is significant. Fortunately the reason for this is obvious and can be fixed. Because of the nature of the Daniel fast, natural sources of HDL cholesterol (such as lean meat) are eliminated. Hopefully these results can be adjusted by introducing certain sources of HDL cholesterol into the Daniel fast diet, in order to determine whether this corrects the problem. Indeed, a follow-up study examined this very issue.6
Published in 2013, the study involved twenty-nine individuals. Sixteen followed the traditional Daniel fast diet, and thirteen did a slightly modified version. The modification introduced one serving of lean meat or skim milk daily to supply natural sources of HDL cholesterol. Again, the compliance rate was high and comparable between the two groups, with the traditional showing a slightly higher compliance rate (96.0 ± 0.94 percent versus 91.4 ± 3.1 percent for the modified group).
The study again showed improvement in reduction of risk factors for cardiovascular disease for both groups, in terms of reduction of total cholesterol. In relation to HDL cholesterol levels for the two groups, the traditional Daniel fast group saw more reduction (13.3 percent) in comparison to the modified group (7.6 percent). Granted, the difference between the two groups in regard to HDL is not statistically significant. Still, considering the relatively small sample size involved, the difference between these two is important.
What is the practical relevance? Both studies show that while the Daniel fast is beneficial to cardiovascular and metabolic health, you need to be intentional in including natural sources of HDL in your diet during a Daniel fast, especially if you plan to make it part of an ongoing lifestyle. Some natural sources of HDL cholesterol include lean meat (avoid meat with fat that can cause additional problems), skim milk, fish (salmon or tuna), avocados, nuts, peanut butter, flax seeds, and olive oil. Physical activity and exercise and weight loss will also boost your HDL level.
Another form of Christian fasting investigated scientifically for its role on human health is fasts for Lent and related Greek Orthodox occasions. For many Christians, the forty-eight days before Easter are usually a time to engage in dietary restrictions. Often, during this period—known as Lent—many Christians abstain from dairy products, meat, and eggs. They may use olive oil on weekends, and fish is only allowed on March 25 and on Palm Sunday, which is a week before Easter. Greek Orthodox Christians practice a similar fast during the forty days before Christmas.
Both types of fasting are similar, and studies on both also report similar results. In general, studies on Lent and other Greek Orthodox fasts show that they lower total cholesterol, as well as LDL cholesterol, which is good for the heart. However, the effects of this fasting on blood pressure and other health indicators are either inconclusive or conflicting. For example, while one study showed that the blood pressure for participants dropped, another study did not find a significant difference between the blood pressure of fasters and non-fasters.7 Therefore, more studies of this type of religious fasting need to be completed.