In the advent of 2019, we are inspired to set new goals, pursue life-long dreams, or simply make better choices. Perhaps, one of the most common reveries we wish to realize is to be able to adopt a healthier kind of lifestyle. With this in mind, some of us look for ways to feel dutifully healthier, such as by managing our weight. So, many would turn to fad diets and caloric restrictions that promise to help. One of them is intermittent fasting. Based on studies, intermittent fasting does not only help trim weight but it seems to offer further health benefits as well.
Intermittent fasting – overview
In May 2018, I wrote the article: “Intermittent Fasting – benefits and caution“. There, I tackled briefly about intermittent fasting, its benefits, and potential risk. In essence, intermittent fasting is a cyclic pattern of a period of fasting and a subsequent period of non-fasting. The most common forms are: (1) whole-day fasting and (2) time-restricted eating. Whole-day fasting entails one-full day of “no eating”, done twice a week (thus, referred to as “5:2 plan“). In time-restricted eating, there is an interval of fasting and non-fasting on a daily basis. It could be half a day of fasting, and then the remaining half as the non-fasting period. With intermittent fasting, it’s not so much about “what to eat…” or “how much…” Rather, it’s more about a question of when.
Intermittent fasting became popular because it does not only help curb weight but it also implicates other health benefits. It apparently slows aging and boosts the immune defense. However, as I pointed out in that article, caution should still be taken. Intermittent fasting is not for everyone, especially those who are immunocompromised and underweight.
Rejuvenating effects of fasting
Previously, I mentioned that studies confirming the health benefits of fasting were done on non-human subjects (e.g. rodent models). Without much scientific proofs of efficacy on humans, what would, therefore, be definite is doubt. However, on January 29 of this year, a team of scientists from Okinawa Institute of Science and Technology Graduate University (OIST) and Kyoto University reported rejuvenating effects of fasting on human subjects. They published their findings in Scientific Reports. Accordingly, they analyzed the blood samples from four fasting individuals. They also monitored the levels of metabolites involved in growth and energy metabolism. What they found was quite interesting and promising.
Dr. Takayuki Teruya, one of the researchers of the team, said that their results implicated the rejuvenating effects of fasting. They found that many metabolites increased significantly, about 1.5- to 60-fold, in just 58 hours of fasting. In their previous study, they identified some of these metabolites (e.g. leucine, isoleucine, and ophthalmic acid), that typically deplete with age. According to Dr. Teruya, they found that the amount of these metabolites increased again in individuals who fasted. Also, they conjectured that fasting could possibly promote muscle maintenance and antioxidant activity based on the metabolites they found. Hence, fasting may probably promote longevity as well. Dr. Teruya further said that this was not yet known until now since most studies that have said so used animal models.
Fasting increased metabolism
During fasting, the body turns to alternate energy stores when carbohydrates are not available. Thus, the less-common metabolites from alternative metabolic pathways superseded the typical metabolites from carbohydrate metabolism. They identified butyrates, carnitines, and branched-chain amino acids as some of the metabolites that accumulated during fasting.  Apart from this, the researchers also found an increase in Citric acid cycle intermediates. This means that aside from prompting alternate metabolic pathways, fasting has also augmented the common metabolic activities. The metabolism of purine and pyrimidine seemed also heightened, indicating an increase in gene expression and protein synthesis. Because of this, the researchers also saw a boost in antioxidants (e.g. ergothioneine and carnosine) that protect cells from the free radicals produced by metabolism. The researchers assume to be the first to provide evidence of antioxidants as a fasting marker. 
This new-found proof infers that fasting seems to have some anti-aging effects, this time, on human subjects. Their next step is to see if they could duplicate the results in a larger-scale study. For now, let us remain cautious, look for indubitable substantiation, and weigh in the benefits and risks of all available options.
— written by Maria Victoria Gonzaga
1 Cohut, M. (2018). Intermittent fasting may have ‘profound health benefits’. Retrieved from [Link]
2 Longo, V. D., & Mattson, M. P. (2014). Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism, 19 (2), 181–192. [Link]
3 Teruya, T., Chaleckis, R., Takada, J., Yanagida, M. & Kondoh, H. (2019). Diverse metabolic reactions activated during 58-hr fasting are revealed by non-targeted metabolomic analysis of human blood. ”Scientific Reports, 9”(1) DOI: 10.1038/s41598-018-36674-9.
4 Okinawa Institute of Science and Technology (OIST) Graduate University. (2019, January 31). Fasting ramps up human metabolism, study shows. ScienceDaily. Retrieved from [Link]
Intermittent fasting recently gained popularity as an alternative way to keep one’s weight in check. 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.
Intermittent fasting – recent studies
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
Intermittent fasting – is it for all?
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