Fasting & Immune Health
Fasting boosts the function of neutrophils, the most abundant white blood cells, in the body. As the gut microbiome houses 70% or so of our immune system, practices that optimize our digestion also enhance our immune function. IF has a positive impact on the gut microbiome favoring the growth of beneficial microbes over harmful ones. FMD is strongly associated with immunological regeneration. FMD supports lymphocyte circulation, improves immunological factors, enhances antitumor immunity, and reduces autoimmunity. Fasting may increase the number of red blood cells, hemoglobin levels, and promote T-lymphocyte precursors to enhance immunity.
Fasting & Metabolic Health – blood sugar, lipids, inflammatory biomarkers
IF improves metabolic flexibility, immunity, and lowers inflammation throughout the body. Additionally, it stimulates the production of more efficient mitochondria. IF strategies improve cardiovascular health, lower blood pressure, and help to balance cholesterol and triglyceride levels.
If you read a recent headline, however, you may be thinking otherwise. This poster presentation claimed that time-restricted eating was associated with a 91% increase in cardiovascular death. While that statistic sounds staggering, many argue that this poster ‘study’ was deeply flawed. This systematic reviewfound the opposite reporting that fasting was associated with lowering cardiovascular risk. Combined with exercise, IF has been shown to reduceobese patients’ weight and LDL cholesterol. After 12 months of time-restricted eating, body mass was reduced by 3.4%, and inflammatory markers, lipid profile, and insulin resistance significantly improved compared with a normal diet. In this meta-analysis, while time-restricted eating resulted in improved glucose levels and insulin resistance, twice per week fasting exhibited the greatest improvements in patients with type 2 diabetes compared with a control diet.
What about prolonged fasting? Fasting insulin was lower and insulin sensitivity improved after 36 hours fasting in this trial. Additionally, there was no significant change in resting metabolic rate (RMR) in people following an IF regimen showing that metabolism did not slow down.
IF promotes glucose uptake by the organ tissues and enhances the ability to store glucose as glycogen. IF can also protect the heart from ischemic damage, reduce body mass index and blood lipids, improve glucose tolerance, and reduce the incidence of coronary artery disease by increasing levels of growth hormone. This in turn increases lipolysis and insulin secretion in addition to reducing other glucose metabolism pathway markers. Additionally, this studyfound IF to result in improvements in the inflammatory biomarkers, CRP (c-reactive protein), TNF (tumor necrosis factor), and IL-6 (interleukin-6) in obese patients.
In a review published earlier this year, both IF and caloric restricted interventions observed improvements in blood lipids, glucose metabolism, and insulin sensitivity. IF interventions showed positive effects on blood lipids and glucose metabolism, while caloric restriction led to reductions in LDL-cholesterol and total cholesterol/HDL ratio. Furthermore, lower oxidative stress and inflammation, including lower levels of CRP, were reported when following IF and caloric restriction interventions. Additionally, cycles of FMD can reducecardiometabolic risk factors, including body mass index, blood pressure, fasting glucose, IGF‐1, triglycerides, CRP, and body weight. Studies combining and/or comparing IF and CR interventions demonstrate promising results on cardiometabolic outcomes, especially in populations with specific health conditions such as non-alcoholic fatty liver disease.
Fasting & Body Weight
Individuals following both caloric restriction and IF interventions, including time-restricted, alternate day, and other forms of fasting, reported significantly lower body weight and body fat. Time-restricted fasting can regulate appetite by hormones and peptides, such as leptin, insulin, and ghrelin. ProLon is the first FMD developed to provide the beneficial effects of fasting including cellular rejuvenation, metabolic balance, and abdominal fat loss. After three consecutive months, participants noted:
a 1.6 inch loss in waist circumference with no loss on lean muscle mass
a 3.4% reduction in body mass index; lean muscle mass was preserved
a 5 pound weight loss; primarily abdominal fat
Fasting & Cancer
IF may reduce cancer risk and DNA damage by increasing the levels of insulin-like growth factor inhibitory protein and ketone bodies as well as reducing IGF-1, insulin, and glucose concentrations. IF inhibited tumor growth by impeding glucose acquisition.
What about the idea of fasting during chemotherapy? Fasting appears to create a synergistic effect with pharmacological intervention on suppressing tumor metabolism, strengthening host immunity, and enhancing the sensitivity of cancer cells to chemotherapy. While more research is certainly needed, there is new evidence that prolonged fasting periods of 46-96 hours during chemotherapy can positively influence the quality of life during chemotherapy. Side effects of treatment are, ironically, seem to be much less, if present at all. This breast cancer review found IF to be feasible, safe and able to relieve chemotherapy-induced adverse effects and cytotoxicity. Similarly, this studyfound that fasting ~60 hours (36 hours prior to chemotherapy and 24 hours following chemotherapy) led to an increased quality of life and tolerance to chemotherapy in patients with ovarian and breast cancer.
In preclinical trials, fasting has shown synergistic antitumor activity with cancer therapies thought to be related to reduced IGF-1 levels during fasting, which led to a downregulation of pathways (mTOR, RAS, and AKT) and consequently increased autophagy. Inhibiting mTOR enhances chemosensitivity in many malignant tumors.
While not all cancer patients may be able, or even interested, in IF during chemotherapy, fortunately, at this time, no studies have documented severe weight loss or malnutrition. Monitoring weight, muscle mass, and malnutrition is crucial.
Fasting & Neuroprotective Effects/Cognition
Clinical studies demonstrated that long-term IF improves cognitive disorders and reduces oxidative stress in middle-aged adults. Fasting could inhibit mitochondrial dysfunction and delay cell aging.
Fasting may prevent and alleviate Alzheimer’s disease by regulating neuronal activity and neurogenesis. In animal models of stroke and Parkinson's disease, IF can avoid neuronal dysfunction and degeneration, induce beneficial cellular stress responses, stimulate the expression of genes encoding stress resistance proteins, and increase various neurodevelopmental factor production. Furthermore, in animal models, IF improves cognitive deficits. And prolonged fasting seems to result in neuroprotective effects and an improvement in learning and memory in animal studies.
IF protocols could potentially serve as an effective dietary strategy for managing symptoms and improving the quality of life in individuals afflicted with multiple sclerosis. Current research suggests several mechanisms through which IF may exert neuroprotective effects for patients with multiple sclerosis and Parkinson’s disease including:
regulate blood glucose level and enhance insulin sensitivity
suppress inflammatory response
reshape the gut microflora
autophagy activation, and
reduce oxidative stress.
Fasting & the Gut Microbiome
Studies have demonstrated that IF can shape the gut microbiome and in turn influence host physiology, particularly immunity and metabolism. IF influences gut microbiota as it can improve richness and alpha diversity. Some of the mechanisms by which IF may improve metabolic health, as mentioned above, include reduced free radical production, improved glucose homeostasis, augmented stress resistance and suppressed inflammation. These mechanisms may be at least partially mediated by the gut microbiota as it has been found to serve a role in glucose metabolism and inflammation through microbial metabolites. IF may increase the abundance of specific bacterial strains that may be helpful to treat irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).
Is fasting right for you?
While IF is generally considered safe, not everyone finds fasting beneficial. And you may find that the effects of fasting for you as an individual vary at different periods of time. If you do decide to consider some type of fasting, do so gradually. For example, slowly increase your overnight fast by one hour.
Fasting is NOT recommended for children, adolescents, pregnant, and nursing women. IF is also not appropriate for those with disordered eating challenges, chronic liver or renal vascular disease. If you are diabetic, be sure to consult your healthcare practitioner to be carefully monitored if considering any type of fasting protocol. Cycling women should liberalize their fasting regimen during their menstrual cycle.
Be aware that fasting too aggressively for your body increases cortisol levels because the body interprets starvation as stress. High levels of cortisol as well as extended periods of high cortisol lead to high insulin and blood sugar levels. Elevated cortisol levels also impede our digestion, so when you eat, you don’t digest as well, especially if you eat a larger meal, leading to bloating, gas, and food sensitivities.
Tips to Help with Fasting
Hydration is key - be sure to consume plenty of fluids
Include electrolytes daily – electrolyte minerals assist in energy production
Practice deep breathing exercises
Add magnesium for improved adrenal health
Opt for a light meal when breaking your fast
Aim to sleep at least 7-8 hours nightly
Allow for stress recovery activities to help your cortisol levels reset
Aim to stop eating for the day by 7pm or 8pm, if possible
If you’re undergoing chemotherapy, consider fasting or avoiding carbohydrates the day prior, day of, and day following your treatment. Be sure to discuss with your healthcare team.
Summary
The primary reason for any dietary change is to have a sustainable and healthy lifestyle that helps you meet your health goals. Whether you’re looking to lose weight, prevent disease, improve autophagy, IF is one eating style that may (or may not) work for you. Both IF and CR protocols show promise in improving weight loss, blood lipids, glucose metabolism, and insulin sensitivity and reducing oxidative stress and inflammation. Most importantly, do your best to consume all of your essential nutrients, appropriate amounts of food, and enjoy your lifestyle.
I hope these past two blogs have been helpful and that you've learned something, anything, about a potential pro or con of fasting that speaks to you. If you do consider fasting in any element, be sure it resonates with you.
Be well,
Natalie