Fasting for Life: Medical Proof Fasting Reduces Risk of Heart Disease, Cancer, and Diabetes - Francis E. Umesiri (2016)

Part 1. The Science of Fasting


The standard American diet is full of empty carbohydrates, sugars, fats, excessive proteins, and calories, and it is low in nutrient content. This diet literally causes us to lose nutrients. . . . Most Americans are unknowingly sowing seeds for a harvest of obesity, diabetes, and a host of other diseases by their choices of food and lifestyle habits.



THE INFLUENTIAL RADIOLOGICAL SOCIETY OF NORTH America stunned the world in late 2011 by issuing a press release on some of the research presented at its annual meeting. The eye-opener involved a team of medical researchers from the Netherlands who said they effectively cured fifteen patients with type 2 diabetes (the most common kind) by placing them on a calorie-restricted diet for four months. The patients ate a diet of five hundred calories per day. Using magnetic resonance imaging (MRI) technology, the doctors monitored and analyzed the patients’ cardiac function and pericardial fat—the lump of fatty tissue outside the heart—before and after the trial. They also monitored patients’ body mass index (BMI) by checking the extent of their weight loss. The results showed a decrease in BMI from 35.3 to 27.5; anything over 29.9 is considered obese. Patients also showed a loss of fat around the heart and increased heart function. In medical jargon doctors observed that “pericardial fat decreased from 39 milliliters to 31 milliliters. Their E/A ratio, a measure of diastolic heart function, improved from 0.96 to 1.2.”2

What is particularly astonishing about this study is that none of these patients required insulin injections again, even a year after they had returned to their regular diets and gained weight. Even after a year their heart function still showed improvement. These results are promising and caught the nation’s attention—at least in the medical and scientific communities. However, this study is only one of many in recent years showing that calorie reduction can help prevent diabetes. Or in the case of obese patients with type 2 diabetes at least help with management of the disease.

According to the Centers for Disease Control and Prevention, as of 2014 there were approximately 29.1 million diagnosed cases of diabetes in the United States—mostly type 2 diabetes, and most of them associated with obesity.3Obesity and such related health issues as diabetes represent huge health problems for the nation. Yet it is amazing that something as simple as refraining from eating too much can help prevent this problem. Periodic fasting may well shield you from type 2 diabetes. Results from several reputable medical labs and publications offer convincing evidence. Considering the epidemic proportion of obesity and health risks accompanying carrying too much weight, it is surprising that not enough medical practitioners are shouting about the benefits of calorie reduction from their medical rooftops. Yet maybe that isn’t that surprising, since medical doctors in developed countries are trained to cure diabetes instead of prevent it.

There is encouraging news, though: more doctors are now sharing helpful tips with patients on how to prevent diseases and remain healthy. Still, these doctors are operating more from the goodness of their hearts and an awareness of their obligation to their patients than from medical school training. Plus, preventive measures such as CR are not necessarily a source of income to pharmaceutical companies and their shareholders (which also happens to be us!). As a result, some of these important results haven’t received the kind of medical attention and promotion they deserve. I hope to help bridge this gap.


Although many peer-reviewed, reputable studies show that calorie reduction can significantly reduce the risk of diabetes, I will focus on perhaps the most trusted study conducted in the United States—the National Institutes of Health’s Institute on Aging. The NIH instituted comprehensive, nationwide research to investigate through clinical trials the effect of CR on health biomarkers in regards to diabetes, cancer, and cardiovascular and neurodegenerative diseases. As I mentioned previously, phase 1 of this study is completed and results have been reviewed, vetted, and published in highly reputable journals. Mentioned in chapter 3, CALERIE stands for Comprehensive Assessment of the Long-Term Effect of Reducing Intake of Energy. In the medical field the industry-accepted gold standard for medical clinical studies is human double-blind, randomized studies. CALERIE is such a study.

So, what did the results from the first clinical study show, especially in regard to diabetes and insulin sensitivity? After placing 150 healthy non-obese individuals (ages twenty-five to forty-five) on calorie restrictions of 25 to 30 percent, studies found that regular fasting insulin concentration was reduced by 29 percent or more.4 In lay terms the higher the amount of insulin present in your blood when you are not eating, the bigger the risk of diabetes; this probably indicates you are developing insulin insensitivity. The higher your insulin sensitivity, the healthier you are, and the lower your risk of developing type 2 diabetes. So, people on CR have much higher insulin sensitivity, and a greatly reduced risk of developing type 2 diabetes.

In 2012 two researchers conducted a clinical study in Serbia to test the effect of calorie restriction on people with impaired glucose tolerance. People with defective glucose tolerance are often at high risk for type 2 diabetes and high blood pressure. So, to investigate the effects that low-calorie, high-fiber diets have on these patients, they recruited fifty-five obese persons and divided them into two groups. One group of thirty-five patients followed a low-calorie diet (55–65 percent carbohydrates, 15–18 percent protein, and 22–23 percent unsaturated fats, and 20–40 grams of fiber per day) for twelve weeks. The control group of twenty patients ate their normal diets.

At the end of three months researchers checked subjects’ blood pressure, fasting plasma glucose, waist circumference, index homeostatic model assessment (HOMA-IR, a biological method to measure insulin resistance), HDL cholesterol, and triglycerides. The group placed on calorie restriction with a high-fiber diet showed significant reductions in diastolic and systolic blood pressure, fasting glucose, index HOMA-IR (lower insulin resistance), and triglycerides, compared to the group that ate their normal diet. Interestingly the fasting group also experienced an increase in HDL cholesterol (due to inclusion of unsaturated fats in their diet).5

What does this all mean? In the words of the authors: “These results suggest that implementation of low calorie-high fibers diet with balanced nutritive elements have a positive effect on visceral obesity, fasting glucose, lipid profile, and hypertension in obese people with impaired glucose tolerance and lead to consecutive lowering of cardiometabolic risk.”6

This study reflects what researchers from the National Institute on Aging found in a report published in 1999. They summarized results of the effect of calorie restriction studies on monkeys and other primates. The report, titled “Calorie restriction in nonhuman primates: effects on diabetes and cardiovascular disease risk,” investigated the role of fasting on diabetes and cardiovascular risks. In all the studies reviewed—including works from their own laboratory—fasting proved effective in reducing blood pressure, body fat, triglycerides, blood glucose, and cholesterol; and increased levels of HDL2B.7 What is the importance of HDL2B? It is a subfamily of HDLs (high density lipoproteins, or cholesterol). Low levels of this lipoprotein have been correlated with increased cardiovascular disease risk. In regards to diabetes, fasting reduced blood level of glucose, meaning increased insulin sensitivity—a condition that reduces the risk of diabetes.

Obesity problems

Obesity frequently shows up in studies related to diabetes prevention. The reason: it has been established biomedically that huge weight gain increases one’s risk of such chronic diseases as diabetes, dementia, heart disease, and certain kinds of cancer—especially breast cancer.8 So there is little doubt that excessive weight gain is a potential health time bomb. That’s the bad news. The good news: several studies also show that just a modest weight loss (at least 5 percent) can have a significant, positive impact on one’s health, especially in reducing the risk of diabetes.9

Now, as important as weight control is, we all know that—for many people—accomplishing this is much easier said than done. So, that leads us to the next piece of good news: fasting seems to be effective at helping people lose weight and sustain the loss. Calorie restriction seems to be most helpful, but due to compliance challenges, intermittent fasting (fasting two or three days a week) or alternate-day fasting (fast one day, eat full meals the next) appears to be more practical for many people.10 One recent review article examined intermittent fasting, alternate-day fasting, and long-term calorie restriction. While the study found that all three forms of fasting help reduce glucose levels, insulin insensitivity, and other indicators of diabetic risk, it showed that sustained calorie restriction is the most effective.

In one recent study conducted in Spain, researchers at a teaching hospital wanted to determine the impact of calorie restriction on severely obese patients in terms of their risk of cardiovascular disease. As stated earlier, persons who are overweight are at a higher cardiovascular risk, characterized by endothelial dysfunction. This simply means that inner layers of their blood arteries are not functioning properly (due to a variety of factors). This leads to high health risks, ranging from hypertension to stroke to diabetes.11 One way biochemists quantify how well inner blood vessel walls function is to measure post-ischemic hyperemia index (saRHI), an indirect marker of endothelial function. In general a higher saRHI index is a good sign, and a lower saRHI index is bad.

These Spanish scientists decided to test the effect of calorie-restricted fasting on the levels of saRHI of participating patients. They carried out their study on thirty-four severely obese patients who had been admitted to the hospital. For three weeks these patients followed a very low-calorie diet (about 800 kcal/day). The researchers also recruited obese and non-obese patients and placed them on the same diet. At the end of the study what they discovered was particularly noteworthy: the very low calorie diet had beneficial effects on all three groups in terms of increasing their saRHI. However, the increase was more dramatic in severely obese patients than in obese and non-obese patients, showing that weight loss correlated with the increase in saRHI. In simple terms this study shows that calorie restriction induces weight loss, and this weight loss in return leads to significant improvement in small artery reactivity.12

Here is another important discovery from this study: the markers for metabolic and inflammatory performance were also improved. There was significant reduction in blood glucose levels, systolic blood pressure, LDL cholesterol, and other factors. The reduction in those markers also correlates directly with reduction in diabetes risk.

My goal is not to overwhelm you with scientific data, but to present convincing evidence that fasting (calorie reduction, intermittent fasting, alternate-day fasting or other scientifically studied methods) offers immense benefits—not only in the prevention of diabetes, but also in significantly improving the health of diabetic patients. Many of the results are connected directly with weight loss, but in other studies—even when fasting is not accompanied by meaningful weight reduction—there was still significant improvement in the diabetic condition of patients.

Extensive diabetes study

Perhaps one of the largest human studies ever undertaken on diabetes is the United Kingdom Prospective Diabetes Study (UKPDS), organized in the late 1970s by Dr. Robert Turner and colleagues in Oxford, England. It involved more than 5,100 subjects at twenty-three centers across the United Kingdom. Physicians followed up participants in the study for an average of ten years and collected twenty million data items. Results appeared in a series of reports in top peer-reviewed journals.

One aspect focused on the impact of reduced energy intake on newly diagnosed diabetic patients. A report published in 1990, known in brief as the “UK Prospective Diabetes Study 7,” reviewed the results of this aspect of low-calorie intake and diabetes. It concerned more than three thousand newly diagnosed diabetic patients who were placed on restricted energy intake. Their average body weight was about 130 percent, plus or minus 26 percent of ideal body weight. At the end of the study patients not only lost weight, but also their fasting plasma glucose levels were significantly lower. The researchers wrote, “The study concludes that though weight loss was important, the most important factor in regulating their blood glucose level and improving their condition was reduction in energy intake irrespective of weight loss.”13

What is it about fasting that improves the condition of diabetic patients even when they do not lose weight from fasting? A group of doctors in Italy decided to investigate further. Ilaria Malandrucco and eleven colleagues from the College of Medicine at the University of Rome Tor Vergata in Rome, Italy, decided to study the early effects of very low calorie diets on insulin sensitivity in morbidly obese patients with type 2 diabetes. The results of their work were published in 2012.

They recruited fourteen type 2 diabetic patients (seven men and seven women) aged 60.3 years, ± 3.02 years, who had had diabetes for an average of four years. Patients were extremely obese, in good metabolic control, and consented to use a CR diet alone or a diet with oral hypoglycemic agents (type 2 diabetes drugs). The doctors placed them on a very low calorie diet (400 kcal/day) for seven days; they also performed laboratory tests before and after the fast. The parameters they measured included plasma total cholesterol, triglycerides, Hb A1c (measures level of blood glucose), and other blood levels. These researchers noticed a marked improvement in the metabolic profiles of these patients: average weight loss of 3.22 percent (42 percent of this was fat loss), and decrease in plasma glucose and triglycerides.14 In order words, their diabetic condition improved.

However, this improvement wasn’t so much due to increased insulin sensitivity (which remained about the same even though blood glucose levels decreased significantly), but the improvement observed was a result of the effect the low calorie diet had on β (beta) cell function.15 Simply put, fasting helps diabetic patients by improving the function of beta cells—a type of cells located in the pancreas, whose main function is to store and release insulin. When there is an increase in blood glucose, beta cells respond by secreting some of the insulin they have stored into the bloodstream, which leads to reduced blood glucose levels. At the same time they produce more insulin for storage. This is an important finding in its own right; namely, the knowledge that fasting may have some direct impact on proper function of beta cells. That has great implications for blood glucose. No wonder fasting seems to have such seemingly dramatic effects on type 2 diabetes.

Personal implications

These results are so important it is worth pausing for a moment to consider that these findings are not some esoteric scientific jargon that does not concern you. Science, backed up by the nation’s top health institute, strongly suggests that sustained occasional fasting or planned reductions in energy intake can help prevent diabetes. In fact, other studies involving already obese diabetic patients, such as the study I cited at the beginning of this chapter, strongly suggest that sustained calorie reduction can cure diabetes.

A caution: if you are already diabetic, it is a must that you talk first with your doctor before embarking on any calorie-reduction program. Still, scientific results involving CR in preventing or managing diabetes are so encouraging that you should definitely discuss the possibility of medically supervised, controlled fasting. If you are overweight but not yet diabetic, you are fortunate in reading this book. You can take action. Eat less, cut down on your daily calorie intake, and practice periodic fasting. Do it for yourself and for your loved ones.

If you are healthy and have a good body mass index, then keep it up. These studies by NIH were also conducted on healthy, non-obese individuals like you. This means that to avoid excess weight and diabetes in the future, you need to commit to cut down on calorie intake on a daily basis. This is more than a weight issue; it has everything to do with your long-term health. Adopt the method that works for you. It isn’t about a weight-loss program as much as it is about reducing your overall energy intake—while still eating a healthy, balanced diet.