The Food and Health Survey (2018) conducted by The International Food Information Council (IFIC) concludes that 36 percent of consumers in the United States adhere to a specific eating plan or diet. The prevalence of dieting and personal weight control reflect the various, unique motivations people may have for beginning a diet. Some people may start dieting and eliminating junk food because they strive for weight loss. Others may diet for reasons related to a medical condition and wish to harness certain foods’ beneficial effects to achieve good health.
There are various reasons to begin a diet, but there are also different ways to do so. Three percent of Americans surveyed by IFIC indicated they followed the ketogenic diet, referred to as the keto diet. Four percent of people were on a high-protein diet, and five percent followed a low-carb diet. Across the survey participants, the most common eating pattern was intermittent fasting, cited by 10 percent of respondents.
Intermittent fasting—by way of alternate-day fasting, periodic fasting, and time-restricted feeding— refers to a daily or weekly cycle of eating, fasting, and on and off caloric restriction. This consumption pattern is more than just a trendy weight loss strategy that enables people to quickly decrease body fat and retain lean body mass.
The intermittent fast initially considered an alternative to continuous caloric restriction, is the subject of many clinical trials, and animal and human studies. Researchers investigate this fast as an intervention for metabolic health.
Neuroscientist Mark Mattson, Ph.D., of the National Institute on Aging, author of many past studies and a recent study on intermittent fasts, suggests that there are many ways the effects of intermittent fasting can help the body long term.
Health benefits of intermittent fasting include the decrease of high blood pressure and cholesterol, slowed progression of Alzheimer’s and Parkinson’s disease, and reduced cancer and heart disease risk.
The basis of this eating pattern is the science of the human body and processes that occur when we’re in the fasted state compared to the fed state and during glucose metabolism.
People who want to begin intermittent fasting can benefit from knowing the science behind intermittent fasts and how food and calorie intake during a fast diet impacts the human body.
The Fed State
Insulin and the mammalian target of rapamycin (mTOR) are active and play a vital role in cell growth in the body during a well-fed state. Insulin signals and mTOR pathways encourage cell growth, division, and protein synthesis.
Feeding increases mTOR activity. When active, mTOR inhibits autophagy—the body’s natural housekeeping mechanism. The word autophagy translates to “self-eating,” reflecting the function of this process: to remove and replace damaged cells. A well-fed cell focuses more on growth and division than efficiency and recycling.
Cells and cell components in the fed state are highly acetylated, meaning that molecules receive acetyl groups. Well-fed cells consist of many active genes, including genes associated with cell survival and proliferation. Acetylation loosens the histones—proteins that assist with condensing DNA into chromatin—and enables the reading of DNA to produce proteins.
When you aren’t fasting, your cells can turn on cellular growth and proliferation genes and turn off others associated with damage repair, fat metabolism, and stress resistance.
The Fasted State
The human body reacts to fasting as it would to starvation; it considers low food availability as environmental stress and changes the gene expression of genes crucial to protecting you from stress.
Fasting and exercising activate the 5’ adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. AMPK is an enzyme with a vital role in cellular energy homeostasis; some of its significant functions include activating glucose, uptake of fatty acids, and oxidation when cellular energy levels are low. AMPK inhibits mTOR and demonstrates the opposite effects of it. Receiving signals from AMPK, the cell protects itself by activating autophagy and breaking down fat.
When fasting, the levels of nicotinamide adenine dinucleotide (NAD+) in the body increase because you lack the dietary proteins and sugars responsible for using the Krebs cycle to convert NAD+ into NADH. NAD+ is an essential substance that occurs naturally in every living cell. Some of its many vital functions include controlling DNA repair, assisting mitochondria and enzymes in energy metabolism, and improving the body’s energy levels.
NAD+ activates two of the seven mammalian sirtuins—enzymes that consume NAD—SIRT1 and SIRT3. Researchers examine the role SIRT1 plays in aging and indicate the health benefits of SIRT3 in cardiovascular disease, among other conditions. Sirtuins impact calorie restriction and weight loss. SIRT1, in particular, can incite the body’s natural ways of burning fat, enhancing weight loss, and fighting disease.
SIRT1 and SIRT3 remove acetyl groups from proteins, censoring genes related to cell proliferation. This process simultaneously activates proteins associated with new mitochondria generation.
An identified activator of SIRT1, resveratrol, works with NAD precursors to accelerate cell health and survival. Increasing the body’s resveratrol levels through supplementation enables people to harness resveratrol’s ability to mimic the longevity benefits of caloric restriction even when they aren’t restricting calories. CALERIE’s Resveratrol can encourage weight loss and enhance low-carb, high-fat diets. CALERIE® Resveratrol can give the entire body and overall health a boost, allowing people to use its pro-cognitive effects and ability to combat free radicals—harmful molecules that damage cells and contribute to sickness.
During a fasting period, there is a depletion of liver glycogen stores. Low insulin production and insufficient amounts of insulin to turn glucose into energy prompt the body to compensate by switching to another source: fat. The liver uses fatty acids to produce ketone bodies, acidic in nature and releases them into the bloodstream. Ketone bodies also called ketones, keep acetyl groups in place, activating genes related to damage repair and antioxidant processes.
A lot occurs in the body, even when there is no calorie intake. These processes arise across five stages of intermittent fasting: ketosis, autophagy, growth hormone, insulin reduction, and immune cell rejuvenation.
The Five Stages of Intermittent Fasting
Stage One: Ketosis
Twelve hours after initiating a fast, the body begins breaking down and burning fat—the metabolic state of ketosis. This state leads to the creation of ketone bodies, which act as an alternative energy source for skeletal muscle cells, heart cells, and brain cells when the body can’t use glucose. Two amino acids, lysine and leucine, can only make ketone bodies, not glucose.
The brain uses an estimated 60 percent of glucose when your body is resting and does the same with ketone bodies during a fast. However, when the brain utilizes ketone bodies, the ketones don’t produce as many inflammatory products as glucose. Additionally, they can initiate the production of BDNF, the brain growth factor. Some noted benefits of ketone bodies include its positive effect on mood and mental clarity, reduction of inflammation in some cells, and its potential to reduce cellular damage and cell death in neurons.
Stage Two: Autophagy
Within a day of fasting, the cells work hard to recycle old components and break down misfolded proteins that may contribute to Alzheimer’s disease and other conditions.
The removal of damaged cells and misfolded proteins during autophagy is crucial for the cells and tissues. The onset of neurodegenerative diseases may be the result of decreased autophagy that happens with age.
Fasting inhibits mTOR activity and activates the AMPK signaling pathway only once there is significant depletion of your glucose stores, and your insulin levels begin dropping.
Animal studies demonstrate that autophagy increased in food-deprived mice after 24 hours; magnification of this effect occurs in liver and brain cells after 48 hours. In human bodies, exercise and fasting-induced caloric restriction can increase autophagy in many tissues.
Stage Three: Growth Hormone
Your growth hormone levels can increase significantly within 48 hours due to decreased calories, carbs, or protein, or a complete lack of calories.
This growth occurs because ketone bodies encourage growth hormone secretion. The hunger hormone ghrelin also promotes the secretion of the growth hormone.
The growth hormone has noted benefits, such as its ability to help preserve lean muscle mass, reduce fat tissue accumulation, support mammalian longevity, heal wounds, and promote cardiovascular health.
Stage Four: Insulin Reduction
Within 54 hours of initiating a fast, the insulin levels in your body are at their lowest.
Low insulin levels contribute to mTOR inhibition and autophagy activation and can combat inflammation. Having low insulin levels can increase your insulin sensitivity and possibly decrease your insulin resistance, reducing your blood sugar. Such effects of little insulin are beneficial if your risk of developing diabetes is high. Additionally, these effects can help ward off age-related chronic diseases, including cancer.
Stage Five: Immune Cell Rejuvenation
Seventy-two hours after beginning a fast, the body breaks down old immune cells and creates new ones.
Fasting for an extended period reduces circulating insulin-like growth factor 1 (IGF-1) levels and protein kinase A (PKA) activity in numerous cell populations. IGF-1 exhibits growth-promoting effects on nearly all of the body’s cells, while PKA activates the mTOR pathway.
Animal studies demonstrate that shutting down IGF-1 and PKA causes stress resistance and the regeneration of blood stem cells. Extended fasting periods—more than 48 hours—have the added benefit of preserving lymphocyte counts in people who undergo chemotherapy.
Breaking the Fast
When you’ve reached the point during intermittent fasting where you can break the fast, you should do so with a balanced, nutritious meal that contributes to how cells and tissues the body cleaned during fasting function.
After fasting, consider eating vegetables, plant fats and plant fibers, proteins, and whole grains, while avoiding processed foods, sugars, or junk food.
Having a “clean” fast is what makes this eating pattern work. People on an intermittent fast can drink tea and black coffee, for example, but without added fats or artificial sweeteners or flavors. One goal of intermittent fasting is to keep foods and drinks that trigger insulin production out of the body because insulin deprivation makes the body use fat stores for energy.
To keep the fast clean, people should take advantage of clean, natural ingredients that enhance their cells’ beneficial effects. Exercise and other weight management actions can benefit a fast or diet, but taking clean dietary supplements from CALERIE® can be a significant help. CALERIE® products not only assist in weight loss but also boost NAD+ production, increase longevity, and maximize cellular and total health.
CALERIE’s Pterostilbene, for example, a sirtuin activator, can be useful for those enduring fast periods, as this supplement reduces hunger and cravings. Vital to the entire body, this calorie-restriction mimetic with superior bioavailability can fight oxidative stress, enhance cognitive function, lower blood pressure, and combat inflammation.
CALERIE®, invested in finding healthy ways to limit caloric restriction, utilizes the body’s cells and natural ingredients to boost cellular, physical, and mental health.
When trying intermittent fasting or any diet, understand what works for your body. For instance, intermittent fasting schedules and fasting days may differ from person to person based on their energy needs and fasting goals. Please consult a doctor or health care provider to make sure it is healthy and safe for you.