In a recent study published in the Frontiers in Nutrition journal, researchers examined the impact of intermittent fasting on inflammatory markers in individuals with obesity.
Chronic low-grade inflammation is linked to obesity. Obese individuals have significantly higher levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in their bloodstream, with a two to three-fold elevation compared to those who have a normal weight. White adipocytes produce inflammatory cytokines and chemoattractant molecules under metabolic stress, which activate and recruit immune cells. Dietary restriction for weight loss is important in reducing chronic inflammation as well as pro-inflammatory gene expression. Intermittent fasting has become a popular weight loss regimen in recent years.
Study: Effect of intermittent fasting on circulating inflammatory markers in obesity: A review of human trials. Image Credit: Cozine / Shutterstock
About the study
In the present study, researchers analyzed the effects of alternate-day fasting (ADF) and time-restricted eating (TRE) on body weight and inflammatory markers, namely, CRP, TNF-alpha, and IL-6, in obese patients.
The study conducted a search on Embase, PubMed, and Cochrane Library using various keywords such as fasting, intermittent fasting, time-restricted eating, alternate day fasting, weight loss, inflammation, and inflammatory markers. The search aimed to find information on the effects of intermittent fasting on inflammatory markers, obesity, and other related factors.
The research articles were selected based on specific inclusion criteria. The study required randomized trials with a control or comparator arm involving adult males and/or females with overweight or obesity and measuring alterations in body weight and a related inflammatory marker. Six human trials of ADF and five trials of TRE were retrieved by the search.
Results
Trials show that TRE leads to a weight loss of 1% to 5% over a period of eight to 12 weeks compared to control groups. Fat mass was decreased by 3% to 9% in the trials compared to the control group. In each trial, the controls were able to maintain their lean mass. Only a limited number of studies assessed visceral fat mass. Studies showed that a weight loss of 4% to 5% can lead to a decrease in visceral fat mass by 11% to 13%. However, a weight loss of 3% did not result in any changes in visceral fat mass. Additionally, 5% to 12% of body weight reduction was observed relative to baseline after eight to 24 weeks of ADF. The difference in body weight reduction between the intervention and calorie restriction (CR) groups was not statistically significant. ADF resulted in a decrease of 12% to 18% in fat mass, while lean mass was not affected.
After eight weeks of TRE, there was no change in high-sensitivity (hs)-CRP levels in both the early and late TRE groups compared to the control group, even though there was a 4% to 5% reduction in weight. In another study, resistance training was performed three times a week in conjunction with an eight-hour TRE. At the end of the eight-week study, hs-CRP levels were found to be similar to the control group. Another study found no significant difference in CRP concentrations between those who underwent 12 weeks of eight-hour TRE and the control group, despite a 4% weight loss. A 6% to 10% weight loss resulted in a decrease in hs-CRP or CRP in almost all studies.
Individuals undergoing four-hour and six-hour TRE experienced a 3% decrease in body weight after eight weeks. However, there was no change in TNF-alpha concentrations compared to the control group. In another study, participants with obesity were assigned to follow either early six-hour or late six-hour TRE for a duration of eight weeks. They found that both the early and late TRE groups experienced a decrease in body weight, with the early TRE group showing a slightly more significant reduction by 5%. However, there was no change in TNF-alpha levels compared to the control group. One study discovered that both ADF and CR for 24 weeks resulted in a 7% reduction in body weight among overweight or obese adults. However, this level of weight loss did not impact TNF-alpha levels.
Both four-hour and six-hour TRE did not result in any changes in circulating IL-6 compared to controls in men and women with obesity. Both groups experienced minimal weight loss, and there were no observed alterations in visceral fat mass. Both ADF and CR groups achieved clinically remarkable weight loss after 16 weeks, but there was no change in IL-6 levels. Two studies found that ADF and CR did not affect plasma IL-6 levels after 24 weeks, despite significant weight loss and reduction in visceral fat mass.
Conclusion
The study findings showed that intermittent fasting does not significantly impact important pro-inflammatory cytokines in the bloodstream. While ADF was found to reduce plasma CRP levels after achieving a weight loss of more than 6%, no significant effect was observed on TNF-alpha or IL-6. No significant changes in inflammatory parameters were detected in relation to TRE, even with a 5% reduction in weight. Further research is required to confirm the impact of intermittent fasting on inflammatory markers, as current data in this area is limited.
Obesity-related heart disease deaths rise sharply in the U.S. between 1999 and 2020