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 as methods for possibly achieving weight loss. However, IF may also provide some other benefits due to its possible effects on metabolism and, if restricted to certain times of day, chronobiology as well.
Weight and metabolism play a large role in the development of cardiovascular disease (CVD), which encompasses 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 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 can help prevent CVD 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.
Periodic Fasting (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 (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 (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
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
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 (CER)
Reduced daily caloric intake to achieve weight loss with no time restriction.
Ad libitum feeding
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.
Other Articles in Issue #78 (April 2021)
Mini: How much can the concept of “food addiction” explain overeating and obesity?
Is food addiction a useful concept? In this Mini, we quickly cover the main points of agreement and disagreement from a recent debate between two experts in the field.
Deeper Dive: Investigating the relationship between vitamin C, type 2 diabetes, and heart disease
Vitamin C supplementation seems to make a dent in blood pressure in people with diabetes. Its effect on glycemic control is less certain.
Dairy disappoints: No beneficial effects found for glucose management
Observational studies suggest that dairy may help with glycemic control. But this randomized controlled trial tells a different story.
Deeper Dive: The effects of melatonin on sleep quality in the context of various diseases
Melatonin works particularly well to improve sleep quality in people with metabolic and respiratory diseases, but the effect size isn't huge.
Mini: Sex differences in the association between body composition and cardiovascular mortality
Higher muscle mass predicts a lower risk of death from cardiovascular disease in men. But in women, higher fat mass plays this role. In this Mini, we give some details and possible explanations for these recent findings.
Comparing animal and plant protein in the context of resistance training
Are high-protein vegan diets any different from high-protein omnivorous diets when it comes to gains? This study aimed to find out.
What’s better for improving inflammation: exercise or caloric restriction?
In people with overweight or obesity, combining exercise with caloric restriction leads has the biggest impact on inflammation, according to this recent meta-analysis.