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Deeper Dive: Investigating intermittent fasting for protection against heart disease

Intermittent fasting could be heart-healthy, but more data is needed before saying for sure.

Study under review: Intermittent fasting for the prevention of cardiovascular disease


Intermittent fasting (IF) is a dietary plan that involves restricting eating to certain days of the week or time of day. Various IF routines have gained popularity[1] as methods for possibly achieving weight loss[2]. However, IF may also provide some other benefits due to its possible effects on metabolism[3] and, if restricted to certain times of day, chronobiology[4] as well.

Weight[5] and metabolism[6] play a large role in the development of cardiovascular disease (CVD), which encompasses[7] conditions related to the heart and blood vessels such as coronary heart disease, heart failure, hypertension, ischemic heart disease, and stroke. There are many factors that increase the risk of developing CVD. In 2019, the American Heart Association (AHA) and the American College of Cardiology published guidelines on the primary prevention of CVD, stressing that the most important way to prevent atherosclerotic vascular disease, heart failure, and atrial fibrillation is to promote a healthy lifestyle throughout life. Part of this healthy lifestyle includes consumption of a healthy diet and, for adults with overweight or obesity, restriction of calories to achieve and maintain weight loss. In 2017, an AHA study[8] reported a weight reduction of 3–8% over six months was associated with a decrease in total cholesterol, LDL cholesterol, and triglycerides. Scientists have become interested as to whether IF[2] can help prevent CVD[9] through weight-mediated or unrelated mechanisms. The study under review evaluated how successful IF actually is in terms of preventing CVD.

Several types of IF regimens have been reviewed in past issues of Study Deep Dives, but since the study under review has very specific definitions for the different types of IF, it’s worth going over them again. The specific definitions for the types of IF evaluated in this study are spelled out in Figure 1. Figure 1 also provides definitions of other eating patterns referred to in this study.

Figure 1: Types of IF and other eating patterns referred to in this study
Eating patternDefinition

Periodic Fasting[10] (PF)

Cyclical pattern of fasting (eating no more than 25% of maintenance calories) for 1 or 2 days per week, with unrestricted eating the rest of the week.

Alternate-day fasting[11] (ADF)

Cyclical pattern of complete fasting (no calories) for 24 hours followed by unrestricted eating for 24 hours. Also includes modified ADF in which the fasting days can include no more than 25% of maintenance calories.

Time-restricted feeding[10] (TRF)

Complete fasting (no calories) for at least 12 hours per day, with unrestricted eating for the rest of the day. This pattern is repeated every day. Note that this is the type of intermittent fasting that people in the fitness and general health community tend to reference when they are talking about intermittent fasting.

Religious Fast – Islamic Ramadan fast[12]

For one month each year, refraining from eating and drinking from sunrise to sunset. Between sunset and sunrise there can be unrestricted eating.

Religious Fast – Greek Orthodox fasts[12]

Abstaining from dairy, eggs, and meat for 40 days during the nativity fast, for 48 days during the Lent fast, and for 15 days during the assumption fast.

Continuous energy restriction[13] (CER)

Reduced daily caloric intake to achieve weight loss with no time restriction.

Ad libitum feeding[14]

Eating based on a person’s usual eating habits with no time or calorie restriction.

Intermittent fasting, in different forms, has become a popular weight loss strategy. There is a strong association between overweight, obesity, and CVD. Scientists have begun to study which types of eating patterns are associated with CVD risk factors. This review was designed to determine the role of IF in preventing and decreasing the actual risk of CVD.

What was studied?

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Other Articles in Issue #78 (April 2021)