Today, we are bombarded with high-calorie foods; sweetened coffee, sugary drinks, processed snacks, and convenience food. This environment of caloric excess is at odds with our evolutionary past. In combination with our modern sedentary lifestyle, this sets us up for obesity, type II diabetes and other metabolic diseases. Our hunter-gatherer ancestors did not eat three meals a day, nor did they snack at regular intervals. Their eating patterns would regularly involve intermittent periods of reduced food (energy) intake.1
Now, some in the science community are saying that mimicking this intermittent fasting could be a simple, convenient, and cost-effective ancestral strategy for reversing type II diabetes.
Fasting is not a new dietary strategy. It became a spiritual practice, used widely amongst virtually all the major religions. At the turn of the 20th century, American physicians Frederick Allen and Elliott Joslin wrote extensively about fasting for diabetes management.2,3,4 This was before its use as a therapeutic tool fell out of favor during the pharmacological revolution of the 1950s.
Rates of diabetes are at an all-time high. One out of two Americans is pre-diabetic or diabetic, and insulin resistance has shown promise as a reliable predictor of age-related chronic diseases.5,6,7 Chronically elevated blood sugar and insulin levels are a hallmark of type II diabetes. Fasting (or intermittent fasting) has been shown to be effective in the short-term for reducing hyper-insulinemia, supporting weight loss, and improving metabolic markers associated with diabetes.8,9,10,11,12,13,14,15,16,17,18
Hyper-Insulinemia & Diabetes
In general terms, the more overweight or out of shape you are, the more insulin your cells require to accomplish the same task as a fit or lean person. Too many years of excessive caloric intake, typically from too much sugar and calorie-dense processed foods, chronically stimulate the pancreas. The body responds to this exaggerated stimulus by dampening its response. To appreciate the magnitude of the response, for every 1uU change in your insulin levels (not a dramatic shift,) you’ll experience approximately a 20% increase in insulin resistance.19 In essence, your cells refuse to take in more energy in a last-ditch attempt to save themselves.
The research supporting hyper-insulinemia as a cause of insulin resistance is sparse, but has considerable merit. Patients with pancreatic tumours that stimulate beta-cell activity (the insulin producing cells) to the greatest degree also have the greatest insulin resistance compared to less insulin resistance in the milder forms.20,21 In another study, researchers infused a constant physiologic dose of insulin into healthy, non-insulin resistant men whom all developed an artificial insulin resistance as a result.22 This artificial scenario actually sounds a lot like the standard American diet – a steady stream of sugar and calorically-dense (nutrient poor) foods eaten continuously throughout the day.
Most type II diabetic patients know that the insulin injections they use in their treatment leads to further weight gain (and thus the need for more insulin). Most diabetes doctors will tell you insulin injections make their patients more insulin resistant in the long run, worsening their condition, and thus increasing their need for insulin over time.23
Fasting & Diabetes
Your body’s physiology is naturally hard-wired to fast; a result of thousands of years of evolution. When fasting, blood sugar and insulin levels fall and your liver begins to breakdown glucose stored as glycogen to fuel your vital organs and brain.
This is a very important because a liver overloaded with too much glucose will build up fat. Studies have shown that excess hepatic (liver) fat (independent of total and visceral fat) is associated with elevated blood sugar and hyper-insulinemia.24,25 It also leads to increased fat deposition to all areas of the body, including the pancreas, negatively affecting the beta cells that produce insulin.26
Insulin functions a lot like a fuel selector switch and as levels fall, the body shifts to primarily burning stored body-fat for fuel. Unfortunately, caloric excess is the norm today in Western countries, unlike the periods of food shortage our hunter-gatherer ancestors endured. The resulting of our Western dietary excesses is in chronic hyper-insulinemia and epidemic levels of diabetes across the globe.
The Research on Fasting
Unfortunately, the research on fasting is still very limited. However, there is increasing data on intermittent fasting (IF), alternate day fasting (ADF) and other forms of time-restricted feeding (TRF) to help provide a glimpse of potential benefits for type II diabetes.
A recent meta-analysis found intermittent fasting (IF) reduced fasting insulin levels 20-30% and blood sugar levels 3-6% in diabetics.27 The study authors concluded “…preliminary findings show promise for the use of IF and ADF as alternatives to caloric restriction for weight loss and type 2 diabetes risk reduction in overweight and obese populations…” while cautioning more research is needed.8 Intermittent fasting has also been shown to protect kidney function,which is important for diabetics as diabetic nephropathy is common complication of the disease.28
Cardiovascular disease is another common risk in diabetes patients.7 Multiple studies have found time-restricted feeding (TRF) can lower body-weight, triglycerides and LDL cholesterol, while increasing HDL cholesterol, all reliable markers for reducing CVD risk.29,30
Inflammation and oxidative stress are also hallmarks of poor metabolic health and diabetes, and recent studies have shown potential benefit of fasting to fight inflammation and increase resistance to oxidative stress.31,32,33,34
Fasting (and its variety of forms) may be an effective nutritional strategy for correcting hyper-insulinemia, reversing diabetes, and improving cardio-metabolic complications associated with the disease. The benefits of fasting likely stem from a simple mechanism: it induces a caloric deficit. Fasting is simple, cost-effective, and it doesn’t matter what type of diet you’re currently following. If you struggle with type II diabetes, look for qualified doctors, like diabetes expert Dr. Jason Fung MD who uses fasting extensively in his Intensive Dietary Management program for diabetic patients. Regardless whether you intermittently fast, simply “fast” between meals (by not snacking), or perform a therapeutic fast under medical supervision, build a habit out of your new nutritional strategy and you’ll discoverthe foundation for reversing hyper-insulinemia and diabetes.
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