Understanding Fasting As A Modern Tool To Aid In Preventing Disease, Weight Management, and More

Disclaimer + Warning


I am not a nutritionist, dietitian, or a doctor. I do not intend to use my experiences as a means of entitlement to tell you how to lose weight, eat, exercise, etc. I am simply using this opportunity as a means to explore some of the reasons as to why I have struggled with my weight and eating behavior as an adolescent and adult, how I reframed my beliefs surrounding food and eating habits, and created a new lifestyle that will carry me healthily through life for a long time. If you have a history of disordered eating and believe this may trigger you, please do not read any further. I speak about weight loss, fasting, and nutrition in a scientific sense. Fasting for people who are diabetic is potentially deadly due to dangerous dips and spikes in blood sugar. I highly recommend that you speak directly with your physician and get your blood work tested before beginning any type of change in diet or exercise routine.

This post is not a manual on how to safely and effectively fast. For this information, I recommend checking out Dr. Stephanie Estima’s ‘The Complete Guide To Short & Long Term Fasting’. In this blog, I discuss correlation, cause, and effect between studies regarding fasting, starvation, and disordered eating along with researchers’ biological, physiological, psychological, and behavioral findings. I also help to distinguish differences in research motives, goals, and parameters that are becoming less and less clearly defined in conversations surrounding health and wellness. This information is arguably some of the most viable in the health industry, due to the fact that fasting doesn’t cost anyone anything. Any doctor or nutritionist that recommends fasting is not making a penny off of that recommendation, and is only making it for the sake of the patient’s health.


As stated in my weight loss/fitness/health journey, I set out on a fasting cycle adventure in order to rewire my behavior and thought patterns surrounding food and eating. To read more about my personal experience and how my mind and body reacted to these intervals, you can click here. After this experience, I spent the next three months dissecting exactly what had occurred in my body physically, physiologically, psychologically, and behaviorally from a scientific standpoint so that I could better understand how my systems were going to be working from there on out, without weekly fasting and with a more regular eating schedule. We’ve all heard the statements about starvation and fat storing, perhaps you’ve heard it said in a way that sounds like, “if you don’t eat your body will think you’re starving it, and it will hold onto more and more fat”. However, from my experience, this had not happened, and I wanted to figure out if the fear-mongering words used around fasting had viable research backing it’s claims, or if it is simply used as a way to deter adolescents from adopting disordered eating behaviors for weight loss.

I began with learning about one of the first research studies associated with fasting to ever be conducted, the Minnesota Starvation Experiment. Despite it’s grave name, it was actually performed by the University of Minnesota Laboratory of Physiological Hygiene in order to learn more about the psychological and physiological effects of hunger and starvation, hoping to reveal valuable information about how doctors would be able to help the world’s population recover from the famine that came of World War II. This excerpt from the American Psychology Association’s article titled, ‘The psychology of hunger’, explains the experiment clearly:


“The research protocol called for the men to lose 25 percent of their normal body weight. They spent the first three months of the study eating a normal diet of 3,200 calories a day, followed by six months of semi-starvation at 1,570 calories a day (divided between breakfast and lunch), then a restricted rehabilitation period of three months eating 2,000 to 3,200 calories a day, and finally an eight-week unrestricted rehabilitation period during which there were no limits on caloric intake. Their diet consisted of foods widely available in Europe during the war, mostly potatoes, root vegetables, bread and macaroni. The men were required to work 15 hours per week in the lab, walk 22 miles per week and participate in a variety of educational activities for 25 hours a week. Throughout the experiment, the researchers measured the physiological and psychological changes brought on by near starvation.”


Something to note is that the experiment did not call for the men to fast, but rather to eat in an extreme caloric deficit while exerting an energy amount that amassed to much more than their daily calorie intake. However, the effects of the study are similar to those of studies on behaviors found in those who suffer from eating disorders like anorexia, bulimia and orthorexia. Effects of the compared two include drastic declines in strength and stamina, heart rate, body temperature, and sex drive. Along with this, psychological effects include obsessions around food, collecting recipes, cooking utensils, and cookbooks, constant conversation about food, extreme fatigue, irritability, and depression. An interesting finding to ponder is the fact that the men in the Minnesota Starvation Experiment reported decreases in mental ability, feeling as though they have low cognitive ability, although when tested, the results did not support that belief. Cognitive ability was equally as strong in “starvation mode” as it was before the experiment began. This has also been proven in recent research, where studies found a lack of differences in mental clarity during fasting periods and a normal feeding schedule.


Looking into my own behaviors during fasting after reading about this study, I remembered having a slight obsession with food storage containers, always finding new colors, types, and sizes to buy. I felt like a little squirrel preparing to store my nuts for the winter or something, it was the strangest thing that I didn’t think much about at the time. I also remember feeling the need to watch Youtube videos of folks eating a huge mass of food, these channels usually being referred to as “challenge eaters” or “mukbangers”. Watching them eat gave me some kind of satisfaction that I can’t accurately put into words, but it was extremely comforting to watch them eat in times of my own hunger (which would only last around 20 minutes until it would subside) during the beginning weeks of the fasting cycles.


It didn’t take long for me to find more and more research about the effects of daily fasting ratios, better known as intermittent fasting, and multi-day fasting- extending periods of twenty four hours at a time, the most common being forty-eight and seventy-two hours long. Biologically, when we fast for sixteen hours and allow ourselves an eight-hour eating window each day, which is a common intermittent fasting ratio, our body uses stored fat for the energy it needs to function, rather than using recently ingested carbs and sugars that our body usually uses for instant energy. This enhances weight loss goals, improves blood sugar control and mental clarity. During a twenty-four hour to seventy two hour fast, the body begins to deplete glycogen, or our body’s carb storage, and lowers it’s insulin levels, allowing the body to burn mainly fat for fuel, making stored body fat much more available for energy needs. Life-long benefits of long term fasting are known to be the following:

  • improved digestion

  • better heart health

  • increased metabolic rate

  • higher energy levels

  • heightened senses

  • reduction in depressive and anxious episodes

  • improved cognitive function, including better memory, and faster learning

  • reduction in inflammation

  • enhanced immune system


Professor of the Longevity Program at the University of Southern California, Dr. Valter Longo, has conducted studies on the benefits of fasting and the fasting-mimicking diet, which consists of a low protein, plant-based diet, incorporating fish once or twice a week. This diet has been shown to show the same responses as fasting, therefore coining the ‘fasting-mimicking’ term. Through his research, Dr. Valter Longo found that mice lived 30% - 40% longer on this diet, along with time-restricted eating, or intermittent fasting. He also found that the mice never fluctuated in weight gain or loss, meaning that their metabolism was high-functioning and consistent. When discussing longevity, it is important to speak about disease, seeing that the leading causes of death in the U.S in 2019 is heart disease, cancer, chronic lower respiratory diseases, stroke, Alzheimers, and Diabetes, along with accidents or unintentional injuries. Dr. Longo’s studies have found that excess levels of glucose paired with a high fat or high protein diet causes insulin resistance, when insulin is released, it causes dysfunction of the muscle and an accumulation of fat, leading to pre-diabetes and diabetes. When mixing a high-carb, low-protein, low-fat diet with fasting, the body creates ‘fasting glucose’ which showed exponentially higher percentages of longevity, weight management, and disease prevention when present throughout the studies. Along with this, Dr. Longo discovered that insulin amplifies mTOR, a mechanistic target of rapamycin which is known as a gas pedal for cellular growth, and when mTOR is amplified above normal stimulation, the activation fuels pro-growth pathways for cancer cells. As cancer is the number two killer of U.S citizens, taking the lives of over 599,000 people every year, Dr. Longo recommends that every person include fasting into their daily and annual diet. Fasting is also proven to lower glucose and insulin levels and enhances the mitochondrial function. When the mitochondria function is compromised, is reduces our ability to burn fat, leads to cognitive impairment, blood sugar issues, and an increased risk of cancer. Specifically, Dr. Longo recommends eating breakfast (contrary to the popular belief among many intermittent fasters that the first meal should be eaten around 12:00-2:00 in the afternoon) and eating another meal or two throughout the day, perhaps including a snack if necessary, in an eight to ten hour window. In recent research, skipping breakfast has been associated with increased risk of cardiovascular disease and overall mortality. Whereas intermittent fasters who eat breakfast and end their feeding cycle around 6:00-7:00 in the evening have a better functioning self-regulatory system in terms of digestion and sleep. This daily fasting ratio of sixteen to eight, with two to three meals and a snack before 7:00 PM has been shown to increasingly break down junk in the body, utilize it for fuel, turn on stem cells, turn on a developmental program and then rebuild throughout the night, creating a well-oiled machine to run efficiently if kept on schedule. Along with time-restricted (I really don’t like using the word “restricted” when discussing food behavior, but this is the term that Dr. Valter Longo uses) or intermittent fasting, Dr. Longo recommends including one or two 5-day water fasts into your diet throughout the year if you are of healthy weight. If you are overweight or obese, he recommends three to four 5-day water fasts annually. Study results found that performing a 5-day water fast puts your body into a detoxifying and regenerative mode, essentially breaking a cycle of glycogen dependance and removing impurities that you’ve been holding onto. In terms of behavioral responses to fasting, people have found that cravings for processed foods disappear, they have a newly refined taste for fruits and vegetables that they never considered desirable before, and they understand their hunger more than ever before. In a podcast interview with Joe Rogan, Dr. Peter Attia mentioned that fasting has created a huge convenience for him in terms of understanding his hunger enough to know that he does not need to eat if he is busy, on a plane for a few hours, etc. and knowing that he will be okay and that his energy levels don’t need to depend on food and the spikes in insulin that food provides. Personally, I feel the exact comfort in knowing that I am able to combat any hunger crabbiness or fatigue that may come along by knowing that my body is substantially stronger than I sometimes give it credit for, and that I also do not need to be constantly eating in order to fuel it. Dr. Longo has donated profits that he has received from his research, and continues researching for and promoting the improvement of the healthcare industry through including alternative treatments along with modern medicine for disease prevention, symptom reduction and cure. Through his studies and research, he has come to the conclusion that a healthy plant-based diet, exercise, and fasting intervals can bring the lifespan average to 110 years old and can also reverse genetic faults, diseases, and illnesses.


I wanted to highlight Dr. Longo’s approaches, theories, and outcomes due to the fact that in other recent research studies, the diet of the study subjects were not clearly mentioned, and long-term results are unavailable. This makes it difficult to measure the overall health of the subjects, aside from weight loss, which is prevalent in almost every fasting study conducted due to a caloric deficit. However, Valter Longo derives his recommended diet and fasting cycles as a result of not only testing on mice, but from studying the people of the Blue Zone, which is five regions of the world that are identified in the book: ‘The Blue Zones: Lessons for Living Longer from the People Who’ve Lived the Longest’, written by Dan Buettner. Residents of the Blue Zones produce higher rates of people who live to be 100 years old or older, stay healthy for longer, and experience a small fraction of diseases that are top killers of populations in other developed parts of the world. The following characteristics is what Dan Buettner discovered to be common throughout each region:

  • Family is put before anything else

  • Less smoking

  • Semi-vegetarianism - the majority of food consumed is derived from plants

  • Constant moderate physical activity

  • People of all ages are socially active and integrated in their community

  • Legumes are eaten often


Venn diagram depicting the common longevity variables among three Blue Zones


In his book, Buettner lists nine lessons he acquired from studying these communities:

Moderate, regular physical activity

  1. Life purpose

  2. Stress Reduction

  3. Moderate caloric intake

  4. Plant-based diet

  5. Moderate alcohol intake, especially wine

  6. Engagement in spirituality or religion

  7. Engagement in family life

  8. Engagement in social life


The incredible findings in Longo’s research are undeniable and absolutely something to consider incorporating into your own routine and diet- if your lifestyle permits it. Throughout reading about his studies, I asked myself the following questions: What about body-builders and physique competitors? What about nurses who work insane schedules, completely throwing off their sleep and hormone regulation? What about the fact that from age zero to twenty-seven, most people feel like they’re invincible and longevity isn’t in their give-a-shit scope? It is unfair to ask these questions to someone whom’s main focal point is longevity, but in terms of lifestyle correlation and possibility, the FMD (fasting mimicking diet) may not be feasible or sustainable for all, despite the fact that it may be a zero-cost preventative measure and cure.


When considering socioeconomic roadblocks that fasting recommendations face, we look to physicians, the overall healthcare industry, and capitalism. Whether you believe it or not, health and wellness is the biggest money-maker in business. The fitness industry will always be booming because weight loss will always be a universal goal. The healthcare industry thrives on the fact that so many people are sick. In order for the system to continue to flourish, people need to keep eating harmful foods, so that they continue getting sick and requiring routine medical care. If doctors began to prescribe fasting as a tool to combat oncoming disease, no money would be made from the patients. I promise I’m not a woo-woo conspiracy theorist, I just understand basic business practices and this is the way the industry works. I’m not necessarily upset about it; as a business owner myself, I can’t be upset about it. However, I do feel it absolutely necessary to open up conversation about why exactly alternative health is called “alternative” and not practiced in mainstream medicine, regardless of the unbiased, non-profitable, viable research and findings that are available.


I believe that fasting is an extremely beneficial tool to try to add to your health and wellness routines if you are in need of rewiring thoughts and behaviors surrounding food due to dependance and addiction, if you are looking to lose weight, and if you want to regulate your hormones, sleep cycles, digestive and immune systems. I would love to see the communication surrounding fasting become much more mainstream in day-to-day conversation with practitioners, friends, and family. I hope that the information I presented here was helpful or educational in a way that leads you to discover more about your body and the way it works so that you may continue or begin to treat it with optimal care and consciousness.


With Love + Grace,


Sadie Kay