Nutrition Intermittent Fasting Meta-Analysis

intermittent fasting

Intermittent fasting explained

New England Journal of Medicine: intermittent fasting (I.F.)

In 2019 The New England Journal of Medicine (NEJM) concluded their meta-analysis citing 388 articles on the benefits of Intermittent Fasting (IF). In this article I summarize the topics that I found most interesting, as well as my own trial of IF.

My Personal Experience

I first tested intermittent fasting at 33 years old. I consider myself a healthy and highly active male. After 6 months of I.F. some I began to notice the following benefits taking place: weight loss (abdominal fat reduction specifically), improvements in my digestion,  and potential decreases in inflammation (though not definitive).

Weight loss was the primary benefit. Digestive system improvements were recognizable from day 1, likely from eating only high quality foods and not eating as quickly as I may have previously. I was also able to maintain muscle tone and strength during the 6 month period. I also noticed a decrease in areas of my body where I’ve experienced chronic pain.

Furthermore, I was able to slow down my usual rushed morning, enjoy a tea or black coffee and avoid force feeding myself before running out the door. I often would eat 2-3 DIRTY Bars (almond butter based) or DIRTY Oats (overnight oatmeal) for my first meal around 12:00pm. This was very simple to rotate through and provided sufficient energy for an afternoon workout as well as the remainder of my work day. Post workout I would often consume 0% Greek Yogurt w/ Berries and walnuts. Dinner in my house is flexitarian (mostly vegetables, some fish, occasional meat).

Additionally, my food planning was more pleasant. I was able to focus going into each meal to optimize the nutritional value of the foods I would end up consuming. Early morning high intensity cycling was a problem for me and I required nutrition post-ride to be able to stay “with-it” both mentally and physically.


According to the NEJM meta-analysis, animals benefited from IF within 2-4 weeks (at 12-16 hours fasting). The benefits tend to go away 2-4 weeks after normal eating practices resume. The next 2 paragraphs site the benefits that were observed in these animal trials. Preclinical studies were performed on animals before being applied to human testing.

IF has been proven to decrease the following in animals : Free Radical Production, Body Weight, Liver Derived Glucose, Adipose Cell Derived Ketones, Inflammation, Diabetes, Cardiovascular Disease, Cancers & Neurodegenerative Brain Diseases.

IF has been proven to increase the following in animals: Glucose Regulation, Stress Resistance, Maintenance, Cellular Repair, Recycling Damaged Molecules, Mitochondrial BioGenesis, Cell Survival, Health Disease Resistance, as well as Mental and Physical Performance through an increase in Ketone Levels.


When the body is in a non-fasting state, glucose is the prime energy source of a cell. After eating carbohydrates, glucose (sugar) is used for cellular energy and fatty acids are stored in adipose tissue as triglycerides resulting in lower ketone levels.

In a fasting state, triglycerides (fats) are broken down into fatty acids and glycerol which become the primary energy source for the cell. Liver converts fatty acids to ketone bodies and fuel the brain specifically. Ketone levels begin to rise within 8-12 hours of fasting. Glucose regulation is improved. Blood pressure and resting heart rate are lowered. The capacity for endurance training improves and abdominal fat decreases. A fasting state also enhances the ability to remove damaged cells (“oxidative damage”) and repair cellular structures, as well as increases resistance to cell damage.

An increase in ketone levels were shown to improve overall health (including brain health) while preventing psychiatric and neurodegenerative disease and aging in certain studies. Animals saw robust lifespan gains (approximately 80% longer in rats) with alternate day fasting. A small human study of 16 people who followed an alternate day fasting protocol showed an average 2.5% decrease in body weight, 4% decrease in fat mass and a 57% decrease in fasting insulin levels.

A larger study of 100 women fasting 5 days a week (5:2) showed that each woman consumed 25% less calories on average resulting in some weight loss and waist circumference reduction as well as greater insulin sensitivity. Another study showed that men who fasted for 16 hours a day over 8 weeks showed a decrease in body fat while maintaining muscle mass.

Intermittent fasting paired with good food choices can enhance natural AntiOxidants in the body. This in turn creates & maintain a healthy cellular environment. An AntiOxidant is a molecule stable enough to donate an electron to a free radical and neutralize it. This can delay & inhibit the free radicals ability to cause cellular damage. B-Carotene, Vitamin C & Vitamin E are all examples of AntiOxidants that must be supplied by your diet and are not created by the body. Plants are full of compounds (phytochemicals) that have antioxidant properties beneficial to the human body.

CRON Diet :

Caloric Restriction & Optimal Nutrition: Okinawans who follow this protocol live approximately 8-9 years longer than the average American consuming the typical western diet. The focus of this CRON is restricting caloric intake while optimizing the nutritional value of the foods you do consume.

Intermittent Fasting on Free radicals :

Free radicals are produced from normal body processes but also from exposure to x-rays, ozone, cigarettes, air pollutants and industrial chemicals. It is crucial that you maintain a balance between free radical and antioxidants in order to maintain normal body function. Too many free radicals will result in oxidative stress and can lead to an alteration in lipids, proteins and DNA. Thus, triggering a number of human diseases including two major and common free radical imbalance diseases, Atherosclerosis and Cancer. Radiation can really impact the balance and cause oxidative stress resulting in the formation of tumors.

*Oxidative Stress by Definition: disturbance in the balance between free radicals and anti- oxidant defenses.

Intermittent Fasting on Cardiovascular Disease :

I.F. was shown to decrease blood pressure, resting heart rate, glucose resistance, insulin resistance, inflammation, oxidative stress & LDL levels (“bad” cholesterol).

M.S. & Arthritis :

3 Consecutive days of fasting showed reduced autoimmune demyelination (Multiple Sclerosis) in rats. Humans have shown a decrease in MS and Arthritis symptoms in as little as 2 months of I.F.  primarily due to decreased inflammation.

Preoperative Fasting :

I.F. improved healing in gastric bypass surgery in humans as well as other wound healing in animals. Evidence has shown decreased mortality and morbidity rates with TBI (traumatic brain injury) and cervical spine injury patients.


After 6 months of disciplined 16/8 fasting (16 hours fasting, 8 hours eating, 7 days a week) I found my experience to be both liberating and mostly pleasant. Intermittent Fasting is something everyone should try out for themselves before writing it off OR recommending it to anyone else. Mounting evidence for cellular level improvements in overall health is reason enough for us all to pay close attention to future research.

Thank you for taking your time to read TDLC. If you want to read the research yourself please see the link below.

NEJM gives 2 free articles per month to anyone who registers, and they don’t collect any payment information. If you want to read the article for yourself here is the link:

-Coach Dirty


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