Intermittent fasting – a cyclic periods of fasting and feasting.
Intermittent fasting recently gained popularity as an alternative way to keep one’s weight in check because of its health benefits. Its basic tenets, though, go against what we had been previously told – to never skip a meal, especially breakfast. We have been accustomed to eating “like a king” as soon as we wake up to prepare the body for the toils and turmoils of the day. Intermittent fasting, though, says that it is alright to put that first meal off until you reach the time window for “feasting”.
Intermittent fasting – overview
Intermittent fasting promises profound health benefits. Accordingly, it can slow down aging, boosts immune defense, and help shed the extra weight.1 All the health benefits are seized if it is done properly. Intermittent fasting is a cycle between a fasting period and a non-fasting period. It may be done in two ways: whole-day fasting and time-restricted eating. Whole-day fasting is the more stringent form. It entails a 24-hour fasting done twice a week (5:2 plan) or every other day (1:1 plan). Time-restricted eating is a daily cyclic period of 16 hours of fasting and 8 hours of non-fasting. The periods are flexible. The pattern can be 12:12 (i.e. equal periods of fasting and non-fasting) or 23:1 (wherein the non-fasting period is set for only one hour). There are no restrictions as to the amount and the kinds of food to eat although consumption of healthy food within the recommended amounts during the non-fasting period is ideal.
Kim and others conducted a research on mice and they found that intermittent fasting helped to kick-start the metabolism and to burn fat by generating body heat in mice. Further, they found that during the fasting period there was an increase in the expression of vascular growth factor, a biochemical essential in angiogenesis and in activating the anti-inflammatory macrophages in white adipose tissue.2 Intermittent fasting may also help improve the ability of intestinal stem cells to regenerate as observed in a study in both aged and young mice by MIT biologists. Accordingly, it seems to have induced a metabolic switch in the intestinal stem cells causing the cells to preferably break down fatty acids instead of glucose.3 These are just some of the studies implicating the potential benefits of intermittent fasting, such as body fat reduction, adipose thermogenesis, metabolic homeostasis, and the preferential utilization of fat-derived ketone bodies and free fatty acids as energy sources via ketogenesis.4
Is it for all? Health benefits and caution
In spite of the purported health benefits of intermittent fasting, this weight loss modality is not recommended for all. Instead of being beneficial, it may be detrimental to the health of those who are immunocompromised and underweight. 4 Thus, consulting a physician should be the initial step. The extent of the positive effects may also differ from one individual to another. Despite the various studies highlighting the health benefits of intermittent fasting, they were done mostly on rodent models. Therefore, further studies are required to validate such promising results in humans.
Unless substantial studies to corroborate the health benefits of intermittent fasting are presented, a window of doubt remains. If in time intermittent fasting proves to be beneficial it would still lead to further queries, e.g. which fasting cycle is the ideal. Also, the effects may vary between young and older people, or between men and women especially when hormones are taken into account. Thus, similar to other weight loss modalities, it is possible that intermittent fasting may work for some people but not for all.
— written by Maria Victoria Gonzaga
1Cohut, M. (2018). Intermittent fasting may have ‘profound health benefits’. Retrieved from https://www.medicalnewstoday.com/articles/321690.php
2 Kim, K.H., Kim, Y.H., Son, J.E., Lee, J.H., Kim, S., et al. (2017). Intermittent fasting promotes adipose thermogenesis and metabolic homeostasis via VEGF-mediated alternative activation of macrophage. Cell Research, 27: 1309-1326. https://www.nature.com/articles/cr2017126′>10.1038/cr.2017.126
3 Trafton, A. (2018). Fasting boosts stem cells’ regenerative capacity. Retrieved from http://news.mit.edu/2018/fasting-boosts-stem-cells-regenerative-capacity-0503
4 Longo, V. D., & Mattson, M. P. (2014). Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism, 19 (2), 181–192. http://doi.org/10.1016/j.cmet.2013.12.008