Bringing this month to a close, we’ll be discussing intermittent fasting (IF)–weight loss and skipping meals. Now it’s important to understand what is known about IF in relation to weight loss and health and the mechanics behind such a technique before going out and trying it. IF is popular, and we want to share what we’ve learned about what advantages it may offer for weight loss and other health benefits. This blog post will discuss what intermittent fasting is and its potential effects on weight loss and health.
What is intermittent fasting? Simply put, it’s “a diet regimen that cycles between brief periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating.” (Diet Review). While this can be done in a variety of ways, the most studied forms include “alternate day fasting (0–500 kcal per ‘fast day’ alternating with ad libitum intake on ‘feast days’); the 5:2 diet (two fast days and five feast days per week) and time-restricted eating (only eating within a prescribed window of time each day).” (Varady et al., 2022)
It’s important to note that one of the main points of intermittent fasting is consistency! This means, regarding whatever your planned schedule may be, doing things at the same time intervals (i.e. skipping meals at the same time, only eating within the allotted time frame, etc.). Another important factor is your dietary intake. As calories and intake are already restricted to a certain degree, it’s best to intake nutrient-dense or nutrient-rich foods, which includes things such as “whole grains, low fat milk and dairy, fruits, vegetables, lean meats, poultry and fish, eggs, beans and peas, and nuts and seeds, all prepared without or minimal added fats, sugars, or sodium.” (Drewnowski & Fulgoni, 2020)
How does intermittent fasting affect weight loss? According to Collier (2013), one hypothesis is that “ … during the fasting period, cells are under a mild stress…and they respond to the stress adaptively by enhancing their ability to cope with stress and, maybe, to resist disease.” Review articles examined, generally found no significant difference in weight loss with IF when compared to calorie restricted diets. Some studies showed improvement in cardio metabolic health while others did not. Most articles noted that studies on intermittent fasting have been small and of short duration, and that more long-term high quality research is needed to establish its benefits.
Yet again, in order for there to be any actual benefit, it’s important to monitor dietary intake so that overconsumption of high-caloric, high-fat foods or, overeating in general, doesn’t occur as it could offset the deficiency in calorie intake.
What are some of the potential effects of intermittent fasting? According to Varady et. al. (2022), “Some studies demonstrate that intermittent fasting improves cardiometabolic risk factors such as blood pressure, levels of LDL cholesterol and triglycerides, insulin resistance and HbA1c, while others show no benefit on these parameters. Intermittent fasting is generally safe and produces few gastrointestinal, neurological, hormonal or metabolic adverse effects.” And according to the National Institution on Aging’s research highlight, Research on Intermittent Fasting Shows Health Benefits, “the key mechanism is metabolic switching, in which fasting triggers the body to switch its source of energy from glucose stored in the liver to ketones, which are stored in fat…the impact of ketogenesis carries over into the non-fasting period and can improve glucose regulation, increase stress resistance and suppress inflammation.”
Overall, it’s important to be properly informed on such topics before practicing them so that behaviors such as binge eating, overfixation on food, etc. do not occur. Thus, as with other things concerning your health, be sure to consult a health professional and/or your primary care physician if you have any questions or concerns.
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Collier, R. (2013). Intermittent fasting: The science of going without. Canadian Medical Association Journal, 185(9). https://doi.org/10.1503/cmaj.109-4451
Diet Review: Intermittent Fasting for Weight Loss. Hsph.harvard.edu. (n.d.). Retrieved from https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/intermittent-fasting/
Drewnowski, A., & Fulgoni, V. L. (2020). New nutrient rich food nutrient density models that include nutrients and MyPlate Food Groups. Frontiers in Nutrition, 7. https://doi.org/10.3389/fnut.2020.00107
Enríquez Guerrero, A., San Mauro Martín, I., Garicano Vilar, E., & Camina Martín, M. A. (2021). Effectiveness of an intermittent fasting diet versus continuous energy restriction on anthropometric measurements, body composition and lipid profile in overweight and obese adults: a meta-analysis. European journal of clinical nutrition, 75(7), 1024–1039. https://doi.org/10.1038/s41430-020-00821-1
Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2022). Clinical application of intermittent fasting for weight loss: Progress and future directions. Nature Reviews Endocrinology, 18(5), 309–321. https://doi.org/10.1038/s41574-022-00638-x
Welton, S., Minty, R., O’Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermittent fasting and weight loss: Systematic review. Canadian family physician Medecin de famille canadien, 66(2), 117–125.
Zhang, Q., Zhang, C., Wang, H., Ma, Z., Liu, D., Guan, X., Liu, Y., Fu, Y., Cui, M., & Dong, J. (2022). Intermittent Fasting versus Continuous Calorie Restriction: Which Is Better for Weight Loss? Nutrients, 14(9), 1781. https://doi.org/10.3390/nu14091781
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Kay Loughrey, MPH, RDN, LDN
Transformational Speaker, Breakthrough Coach, Nutritionist-Dietitian
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