Research Update on Intermittent Fasting

The word breakfast literally means to break the fast because it is the first meal of the day after a period of overnight fasting. Once believed to be the most important meal of the day, a burgeoning amount of research is showing that skipping breakfast and widening the overnight fasting window may enhance health on many levels. That’s where intermittent fasting comes in.

Intermittent fasting (IF) is an eating pattern that emphasizes not what is eaten but when it is eaten, with food consumption limited to certain hours of the day. Time-restricted eating (TRE) is a form of intermittent fasting that focuses on an overnight fast of 14 to 16 hours, creating an eating window of eight to ten hours. This eating pattern has become popular primarily because of its positive influence on weight management.

Latest Weight Loss Research

In June of this year, a randomized controlled trial was published in the Annals of Internal Medicine that looked at TRE without calorie counting. This was a 12-month trial that randomized 90 racially diverse obese adults to one of three groups: TRE with an eight-hour eating period with no calorie counting, calorie counting that reduced intake by 25 percent, and the control, which could eat over a period of ten or more hours per day. There was no statistically significant difference between the calorie counting and TRE group; however, TRE was significantly more effective at producing weight loss when compared to the control. The TRE group lost just over ten pounds on average at the end of the 12 months.

These results are consistent with prior research. A 2020 systematic review of 27 trials found weight loss of 0.8 percent to 13.0 percent of baseline weight. Five of the 27 trials featured type 2 diabetes patients and found improved glycemic index along with weight loss.

Beyond Weight Loss

In addition to facilitating weight loss, IF has been shown to help with blood sugar control, reduce oxidation, inflammation, and the risk of cardiovascular disease, and optimize circadian physiological processes. Research also indicates IF can improve metabolic health, specifically cholesterol and blood pressure.

In a 2021 study featuring overweight adults with type 2 diabetes, a ten-hour TRE window resulted in many benefits, including weight loss, improved blood glucose and insulin sensitivity, reduced dosage of hypoglycemic medications, and enhanced quality of life.

A 2021 systematic review and meta-analysis of randomized controlled trials found that IF improved a variety of cardiometabolic risk factors beyond weight, including waist circumference, blood pressure, total cholesterol, and insulin resistance, compared to the control group diet.

A 2020 analysis looking at inflammatory markers found that IF resulted in a significant reduction in C-reactive protein. In that analysis, IF did not affect tumor necrosis factor-α or interleukin-6 concentrations.

Animal studies are showing that IF can also have anticancer effects and contribute to healthy aging, so it's likely that human trials are forthcoming.

On a cellular level, IF has been shown to positively influence mitochondria, DNA, and autophagy, which removes cellular debris, repairs damaged cellular components, and contributes to proper cellular regeneration. 

In general, fasting is considered safe, especially under the guidance of an integrative practitioner. As the research continues to grow, so will the clinical applications of this interesting eating pattern.