Intermittent Fasting has been gaining in popularity. A recent study found that 10% of the American population participates in this diet. It is a caloric restriction revolving around a short window for eating and a comparatively larger window for fasting. In this article, we review the health benefits against the potential cardiovascular concerns.
Surge in Popularity of Intermittent Fasting
Intermittent fasting has become a popular weight-loss strategy and is effective in fat loss. The dietary regimen cycles between periods of eating and fasting with several methods like the 16/8 method, 5:2 method, Eat-Stop-Eat, and the Warrior Diet, giving individuals diverse options between lengths of fasting and types of meal restriction. Beyond shedding pounds, intermittent fasting has also been associated with other health benefits, including improvements in type 2 diabetes symptoms, metabolic health, and possibly longevity. However, amid the buzz surrounding its potential, it is imperative to continue monitoring research surrounding its merits and potential risks.
New Insights: Recent Research Revelations
Recent research published this year has shed new light on the effects of intermittent fasting on various health outcomes, the gut microbiota, and metabolic changes. Interestingly, a recent conference presentation from a group in Shanghai Jiao Tong University School of Medicine suggested that intermittent fasting might increase the risk of cardiovascular disease.
A Closer Look at the Evidence
Investigating 23 meta-analyses across 34 health outcomes, a systematic review uncovered significant positive impacts of intermittent fasting in 103 of the associations made. Compared to control adults with obesity or who are overweight, overweight adults who underwent intermittent fasting showed reductions in waist circumference, fat mass, fasting insulin, low-density lipoprotein cholesterol, total cholesterol, triacylglycerols, in addition to increased fat free mass. Moreover, adults with obesity and type 2 diabetes exhibited high levels of high-density lipoprotein cholesterol levels compared to counterparts who were under continuous energy restriction.
Comparative Perspectives: Intermittent Fasting vs. Conventional Diets
Another systematic review comparing intermittent fasting to an ad libitum diet and to a continuous energy restriction diet revealed that both intermittent fasting and continuous energy restriction achieved weight loss through fat mass and body fat percentage reduction. However, emerging studies suggest intermittent fasting may be more beneficial than continuous energy restriction in certain contexts. For instance, one study suggested that intermittent fasting combined with protein pacing of consuming 20 to 40 g of protein, reducing highly processed foods, sugar, and fat, further reduced visceral (−33% vs. −14%) fat mass and the desire to eat (−17% vs. 1%), compared to continuous energy restriction. Similarly, another review describes the evidence for combining a ketogenic diet and intermittent fasting to achieve diabetes remission. This combination, by controlling the breakdown of liver glycogen and influencing glucose metabolism, could potentially lower blood sugar levels, thus paving the way for diabetes remission.
The Impact of Intermittent Fasting on Gut Health
A recent systematic review investigated over 940 studies exploring the association between different types of intermittent fasting and gut microbiota richness, alpha and beta diversity, and composition in human subjects. The majority of the studies found a correlation between intermittent fasting and gut microbiota richness, diversity and compositional changes. The increased richness and diversity of the gut microbiota are generally considered beneficial for health. A diverse gut microbiota is associated with a robust immune system, efficient nutrient metabolism, and a lower incidence of diseases such as inflammatory bowel disease and diabetes. Further, a rich and diverse gut microbiome can help protect against pathogens and maintain the integrity of the gut barrier. These compositional changes in the microbiota due to intermittent fasting may contribute to the overall health and well-being of individuals by fostering a more resilient and capable microbial ecosystem.
The Double-Edge Sword of Intermittent Fasting: Cardiovascular Risks
While intermittent fasting shows potential, it has its share of conflicting research results. Recently in a preliminary research presented at the American Heart Association’s Epidemiology and Prevention on March 18- 21, in Chicago, a group from Shanghai Jiao Tong University School of Medicine in Shanghai, China, analysed and followed over 20,000 U.S. adults over a median length of 8 years and a maximum length of 17 years. They found that:
- People who ate all their food within less than 8 hours per day had a 91% higher risk of death due to cardiovascular disease.
- Among people with existing cardiovascular disease, an eating duration of between 8 and 10 hours per day correlated with a 66% increased risk.
- An eating duration of more than 16 hours per day was associated with a lower risk of cancer mortality among people with cancer.
Overall, the authors suggest that time-restricted eating may have short-term benefits but long-term adverse effects. Thus, the authors warned that healthcare professionals must warn patients, particularly those with existing heart conditions to be aware of the association between time-restricted eating and the increased risk of cardiovascular death. It is important to note that these are preliminary research. Therefore, healthcare professionals should confirm the solidity of the evidence once the study has been peer-reviewed and published. Nevertheless, the authors advocate a more cautious and personalised approach to dietary recommendations.
The Role of the Healthcare Professionals
While intermittent fasting holds promise, the latest research still urges vigilance regarding its long-term adverse effects. Healthcare professionals must continue to exercise prudence in recommending dietary interventions. Here are some steps that the healthcare professional can take:
- Comprehensive Assessment: Conduct thorough evaluations of patients’ health status, considering individualised needs and potential risks. Particularly in light of the latest research on the association between risk of cardiovascular death and intermittent fasting, patients with existing cardiovascular conditions should be cautioned to carefully consider this regime.
- Informed Counselling: Provide patients with evidence-based information regarding intermittent fasting, emphasising both its potential benefits and associated risks.
- Personalised Recommendations: Tailor dietary recommendations to align with patients’ health goals, preferences, and medical history. There should be a holistic approach to wellness. For instance, diabetic patients may benefit with a combination of ketogenic diet and intermittent fasting.
- Vigilant Monitoring: Continuously monitor patients’ progress and response to dietary interventions, fostering ongoing dialogue and adjustments as needed. The short-term benefits of intermittent fasting are evident while the long-term effects are less known. Monitoring the patients over time and making gradual adjustments can reduce the risks of adverse effects.
As research continues to evolve, healthcare professionals serve as pivotal guides, steering patients towards balanced and sustainable dietary practices that optimise health outcomes.
Conclusion: Navigating the Complex Landscape of Intermittent Fasting
The global obesity crisis underscores the urgency to discover effective dietary strategies. In conclusion, intermittent fasting emerges as a promising yet complex strategy in the battle against obesity and for overall health improvement. While most findings on intermittent fasting are encouraging, the recent preliminary evidence presented high cardiovascular risks for individuals in the long run. Amid the optimism, it is crucial to tread carefully, acknowledging the necessity for thorough assessment and personalised advice. By skillfully navigating these intricacies, healthcare professionals can guide patients towards adopting dietary practices that promote long-term health.
References
- Arciero, P. J., Poe, M., Mohr, A. E., Ives, S. J., Arciero, A., Sweazea, K. L., Gumpricht, E., & Arciero, K. M. (2022). Intermittent fasting and protein pacing are superior to caloric restriction for weight and visceral fat loss. Obesity, 1-9. https://doi.org/10.1002/oby.23660
- Paukkonen, I., Törrönen, E.-N., Lok, J., Schwab, U., & El-Nezami, H. (2024). The impact of intermittent fasting on gut microbiota: a systematic review of human studies. Frontiers in Nutrition, 11, Article 1342787. https://doi.org/10.3389/fnut.2024.1342787
- Zhong, V. W. (Presenter). (2024, March 18-21). Research presented at the American Heart Association’s Epidemiology and Prevention│Lifestyle and Cardiometabolic Scientific Sessions 2024, Chicago.
- Lange, M. G., Coffey, A. A., Coleman, P. C., Barber, T. M., Van Rens, T., Oyebode, O., Abbott, S., & Hanson, P. (2023). Metabolic changes with intermittent fasting. Journal of Human Nutrition and Dietetics. https://doi.org/10.1111/jhn.13253
- Medical Channel Asia. (2023, May 9). Intermittent Fasting 101: Exploring the Pros, Cons, and Methods. Retrieved from https://www.medicalchannelasia.com/article/intermittent-fasting-101-exploring-pros-cons-and-methods
- Medical Channel Asia. (2023, Mar 17). The Benefits and Risks of Intermittent Fasting. Retrieved from https://www.medicalchannelasia.com/article/benefits-and-risks-intermittent-fasting
- Sun, M.-L., Yao, W., Wang, X.-Y., Gao, S., Varady, K. A., Forslund, S. K., et al. (2024). IF and health outcomes: An umbrella review of systematic reviews and meta-analyses of randomised controlled trials. eClinicalMedicine, 70, 102519. https://doi.org/10.1016/j.eclinm.2024.102519
- Zhou, X.-Y., Guo, K.-H., Huang, S.-F., Liu, R.-K., & Zeng, C.-P. (2024). Ketogenic diet combined with intermittent fasting: An option for type 2 diabetes remission? Nutrition Reviews, nuae014. https://doi.org/10.1093/nutrit/nuae014
