How Inflammatory-Immune Outcomes Vary As A Function Of Behavioral Restrictions
Elizabeth Bowman
University of Miami
Abstract
Our immune system is a complex network that effects our psychological behavior and our neuroendocrine system; But it is also the other way around. Through my research of Intermittent Fasting (IF) and Time Restricted Fasting (TRF) I focus this paper on the evidence that eating behaviors (i.e. in the time frame we are consuming calories in and how many calories we are consuming) have a direct effect on both neuroendocrine and immune systems. Currently in day to day life human beings eat three meals a day, which throughout history we have not been built to do. (3) When we are hungry or stressed we reach for the most unhealthy option sometimes looking at “comfort food” as the answer. (16) Through TRF studies it has been shown that many different chronic illnesses human being suffer from on a daily basis can be improved through TRF/IF such as insulin resistance.(6) As for the immune system IF/TRF has shown to reduce the number of inflammatory cytokines especially IL-6, IL-1β resulting in lowered inflammatory in the body. Which helps the body resist against disease especially anti-aging ailments such as osteoporsis. (15) IF/TRF has also shown to enhace DNA repair in both animal and human subjects.(6) There is still research that needs to be done as IF/TRF has been shown to have different effects on women than it does on men, but many positive outcomes seem to be showing from certain time windows of IF/TRF.
Introduction:
Currently within our society, there has been an influx in articles and in people practicing a kind of “diet” that’s basic principle is intermittent fasting. Intermittent fasting (IF) also defined as time restricted fasting (TRF) actually goes back to the early days of humanity where three meals a day were not what we were consuming. (3) All studies that I researched have used a non-three meals a day system and instead shortened the window of energy consumption to anywhere between six and nine hours the average and most effective being eight hours energy consumption, sixteen fasting.(8) In this paper I am exploring how inflammatory-immune outcomes vary as a function of these behavioral restrictions.
Psychological/Behavioral/Environmental factors:
Most people eat within a twelve to fourteen hour time period, which is biologically not what we were built for or used to. In the studies conducted and reviewed in this paper each participant was put on a diet with a controlled time frame in which they ate. In this way different time frames of fasting were monitored and their outcomes were monitored giving a better idea of which time frame of fasting is ideal for humans and which could possibly cause damage. (3) Also while conduction research Ranges of calories is imperative when studying as large influxes of energy and small influxes need to be controlled. (2) We are used to over consuming food which has led to certain “metabolic morbidities, insulin resistance, excessive accumulation of visceral fat” being two examples. Through changes in our fasting windows, changes are shown for animals and humans to function at higher levels. (6) When we are stressed we reach for unhealthy food choices, leading the body to produce more pro-inflammatory responses. Men and women who are chronically stressed have a much higher level of IL-6 than the average human being, resulting in extreme inflammation. (16) There is however a direct connection between inflammation and emotional disorders. A study done during Ramadan showed a decrease in IL-6 and CRP levels by almost half from before the fasting commenced. A control group that was not fasting showed no change in IL-6 and CRP levels. (16) While the stress itself might not go away immediately the idea that possibly changing a your diet to decrease the inflammatory cytokines in your body could over time reduce chronic stress, anxiety and depression. Along with reducing emotional disorders and inflammatory cytokines the body therefor ends up being less open to immune diseases and viruses. While there are many positive outcomes from TRF so far, the metabolic disease risk rate has not been researched enough and not yet in enough literature where we can say for sure that there is no risk of metabolic disease in humans. (3) Along with metabolic disease, there is the worry for females that intermittent fasting can cause fertility issues and an imbalance regarding hormones. A study done by Sushil Kumar shows that female rats that have been fed along terms of intermittent fasting showed a disrupted hormone and shrunken ovaries. (19) Obviously due to ethics laws no controlled studies have been conducted on women’s fertility in combination with intermittent fasting. More research needs to be done before we can safely assume that intermittent fasting or time restricted fasting is safe for all humans.
Neuroendocrine factors:
As a result to the behavioral eating changes, the neuroendocrine systems also sees results. Shifts in the way fat is metabolized, in ketone production and in cellular stress are all positively effected by IF/TRF.(3) In some individuals experiencing neurodegeneration, when implementing IF/TRF the individuals have shown the process of neurodegeneration slowing down. (5) Insulin resistance improves with certain time windows of IF/TRF (6) In a study done by Fontana and Partridge Rhesus monkeys show substantial improvements in health. The study also showed that IF/TRF “delays the onset of sarcopenia, presbycusis, and brain atrophy; and reduces the risk of developing and dying of type 2 diabetes, cancer and cardiovascular disease.” The same results were shown in humans when studied. (5) Currently cardiovascular disease is the number one cause of death in America. If It was as simple as people reducing their calorie intake and ingesting those calories within a restricted window that could save millions of lives. Along with that, IF/TRF shows positive changes in blood lipids. (8) In the study previously reference using strictly athletic males as test subjects, the results showed that while fat mass decreased in all subjects tests the muscle mass stayed the same and the muscle mass maintained that same strength as right before the study began, even though caloric content had been cut and time window of calorie consumption had shrunken. Testosterone levels also lowered in males after IF/TRF trial. (8) A common result in countless studies was that fat mass decreased as well as blood lipids. This may be a result of one of the main goals of Intermittent fasting, to burn fat instead of glucose. When we keep feeding our body at regular intervals it has constant fuel to burn, and the IL-6 and CRP levels stay level, occasionally raising when we feed our bodies inflammatory foods. When the body is fasting for a significant period of time (anytime over twelve hours) the stored glucose is burned up, leaving the body to look for another source of energy, which ends up being stored fat. The fat gets burned and with that our body is using itself more efficiently. Evolutionarily we were never supposed to have such access to so much glucose, so when we are not eating as much are insulin sensitivity improves as well as our risk of developing type 2 diabetes. (9) While all these factors happen in rats, monkeys as well as humans, there is still the loss of estrogen, and the disruption of hormonal cycles in female rodents as well as shrunken ovaries which is a large negative in terms of implementing a diet. Possibly when women get to a place where they already have children or women who do not want children, then the risk would just be differences in their hormonal cycles which so far we do not know the effects of other than lowered fertility rate.
Immunological factors:
Regarding immune functions and the impact IF/TRF has on the immune system, the impacts of IF/TRF stay relatively consistent between animals and humans. However, the effects vary greatly sick and healthy subjects.(3) In a study measuring IL-6, IL-1β and tumor necrosis factor α, healthy male and female participants were chosen who were practicing fasting during Ramadan. In all cases the inflammatory cytokines IL-6 and IL-1β were lowered as well as tumor necrosis factor a. Furthermore these results showed lower body fat and increased circulation of leukocytes. (15) It has been shown that a lowering of energy consumption while avoiding slipping into starvation has positive effects on organisms, such as ridding the body of age-related diseases such as osteoporosis, neurodegeneration and many more. (5) “The cellular and molecular mechanisms by which IF/TRF improves health and counteracts disease processes involve activation of adaptive cellular stress response signaling pathways that enhance mitochondrial health, DNA repair and autophagy" (6) The hormone cortisol also known as the stress hormone is responsible for activation of the cellular stress response pathways. While cortisol in high doses can be negative, in controlled doses, managed by TRF windows of feeding, cortisol can help the body burn fat and work more efficiently. Within those windows of IF/TRF (most effective hours have been 16 hours fasting, 8 hours consumming) (8) TRF/IF has proven to reduce inflammation in humans and animals. In the study done on Ramadan participants, when fasting for Ramadan finished and subjects returned to their regular eating habits and windows of eating, the inflammatory cytokines IL6, IL-1β were shown to rise again to what they had previously been at before participants had stared fasting.(15) When inflammatory cytokines are lowered, the body for the most part does not contract as many diseases, and has a stronger immune system. As well as that, many bodily age related diseases are not as prevalent, such as osteoporosis, type 2 diabetes and many more. IF/TRF shows many solutions to some of the body’s more prevalent ailments.
Conclusions:
The conclusions that I have gathered from reading research and focusing on studies in the last five years that have used IF/TRF has shown me many different routes that one could take with IF/TRF. There have been endless amounts of studies showing positive outcomes of changing one’s eating behavior to feed during one average eight hour period per day. Those changes include less risk for developing type 2 diabetes, less risk of continued neurodegeneration, less risk of osteoporosis and even cardiovascular disease. (5) It also shows in almost every study that blood lipids decrease and fat mass decreases.(8) These are large challenges for our world today. People’s diets are incredibly unhealthy and the obesity epidemic is a very real problem. Changing what we eat and when we eat it could change levels of chronic stress as well as many other emotional disorders. (16) On the other hand, there has not been enough research into the possibility of developing metabolic disease from IF/TRF. (3) Along with the danger of metabolic disease, there is also the data showing that female rats when made to practice IF/TRF show hormonal cycle disturbance as well as shrunken ovaries. (19) I think that while IF/TRF shows many attractive aspects that could help human beings there needs to be more research done before it can be suggested as a safe and healthy way of eating for human beings to practice as part of their daily life.
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