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Intermittent fasting may prevent diabetes

Analysis by Dr. Joseph Mercola Fact Checked

intermittent fasting may prevent diabetes

Story at-a-glance -

  • Intermittent fasting helps reduce fat accumulation in the liver; recent research shows it also reduces fat deposits in the pancreas, which helps prevent development of Type 2 diabetes
  • Insulin resistance reduces the ability of the body to use glucose, raising your blood glucose levels; intermittent fasting involves incorporating one or two fasting strategies that fit your lifestyle, including a 12-hour- or 16-hour-a-day fast, meal skipping, two-days-a-week fast or every-other-day fast
  • Fasting improves your metabolic flexibility so you may burn fat and glucose for energy. This is vital for optimal health and reduces metabolic inflexibility related to insulin resistance
  • Fasting may be started slowly by initially starting it from 7 p.m. to 7 a.m.; most of the hours you'll be sleeping, and progressing from there; by adding one hour a week to your fast you'll be fasting 16 hours a day within five weeks

Diabetes is a disease of insulin resistance resulting in high blood sugar.1 Your pancreas secretes the hormone insulin, which is used to move blood sugar across cell walls for energy.2 The number of those experiencing diabetes has risen sharply since 1958, when the CDC3 estimated 0.93% of the population had been diagnosed with it.

By 2015 the number had risen to 7.4%. As the population numbers had also increased, the absolute numbers diagnosed were 1.6 million in 1958, rising to 23.4 million in 2015.4 The percentage of the population diagnosed with diabetes rose slowly from 1958 to 1995, at which point it began increasing more quickly from 3.3% of the population to 7.4% in 2015.5

Another report from the CDC6 encompasses the total number of existing cases, including newly diagnosed diabetes. According to this report it is estimated that in 2015, 9.4% of the U.S. population or 30.3 million people were diabetic. When they factored in those who may not be aware of their diagnosis, the percentage rose to 12.2% of all U.S. adults.

One future model7 predicts that without change, the prevalence will increase 54% to more than 54.9 million Americans by 2030. According to the World Health Organization,8 422 million people around the world, or 8.5%, were diagnosed with diabetes in 2014; this represents a 3.8% increase from 1980. The disease is a principal reason for blindness, heart attacks, strokes, kidney failure and lower limb amputation.9

Diabetes is one of the most expensive chronic diseases10 and is estimated to cost more than $245 billion per year in the U.S. The future model published in the Population of Health Management estimates this will rise to $622 billion by 2030.11

Whatever metric is being used to measure, the numbers are rising. Current treatment philosophy12 holds that you can manage the disease with making healthy eating choices, being active and using prescription medications, such as insulin, to control blood sugar levels.

A recent study13 published in the journal Metabolism demonstrates how intermittent fasting, known to improve sensitivity to insulin14 and to protect against fatty liver disease,15,16 may also reduce pancreatic fat deposits and help prevent development of Type 2 diabetes.

Preventing diabetes with intermittent fasting

When your body is insulin resistant,17 the cells in your body do not respond well to insulin, which lowers their ability to use glucose from the blood for energy. The pancreas secretes more insulin, trying to overcome the cells’ weak response and keep blood glucose levels in a healthy range.

A research team from the German Institute of Human Nutrition undertook a study to determine how weight-induced fat buildup in the pancreas has an effect on the onset of Type 2 diabetes.18 Using an animal model, the study team found that overweight mice prone to diabetes also had a high amount of fat in the pancreas.

If mice were genetically resistant to diabetes, despite having excess body weight, their pancreas did not carry fat deposits. However, researchers did find additional fat deposits in the liver of these mice. The team used New Zealand obese mice who were split into two groups.19

One group was fed a high-fat diet and allowed to eat as much as they wanted, and the second group fasted every other day. The researchers measured fat in the pancreas, glucose homeostasis, insulin sensitivity and islet of Langerhans function (cells in the pancreas where insulin is produced20).

They found the mice in the experimental group, undergoing intermittent fasting every other day, had better glucose control and less fat in the pancreas and liver than the control group who were allowed to eat as much as they wished each day.

When a variety of cell types from the mice were cultured together, researchers found fat cells in the pancreas developed a hypersecretion of insulin and released more fatty acids than white fat cells harvested from the lower stomach and groin area.

Based on these results, the researchers suggested21 that pancreatic fat plays a role in the development of Type 2 diabetes, but intermittent fasting may prevent pancreatic fat deposits.

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How do you define intermittent fasting?

There are several different ways of integrating intermittent fasting into your daily routine. The process involves entirely or partially foregoing eating for a specific amount of time. The methods will vary on the number of days, the number of hours and how many calories you’re allowing.22

Some find it challenging to stick to a program, but remaining hydrated, avoiding obsessing over food and finding the time to engage in relaxing activities such as yoga may help.23 While there are different ways of incorporating intermittent fasting into your routine, there is no one single plan that works for everyone.

You'll experience the best results by trying several to see what fits with your lifestyle and preferences. The goal behind intermittent fasting is to improve your metabolic flexibility,24 or your body’s ability to respond to changes in metabolic demand.

As you try intermittent fasting, it's important to remember that the meals you do eat should be well-balanced, high in healthy fats and low in carbohydrates. Here are several different methods to consider:25

12-hours-a-day fast — This is often used as a jumping-off point for those who are interested in starting intermittent fasting. You need only adhere to a 12-hour fasting window every day, including the hours you sleep. This is easily done when your last food is eaten at 7 p.m. and you don’t eat again until breakfast the next morning.

16-hours-a-day fast — During a 16-hour fast you have an eight-hour window to eat. It's sometimes referred to as the 16/8 method and is a graduation from the 12-hour fast. In this case, many people finish eating by 7 p.m. or 8 p.m., skip breakfast and do not eat again until noon.

In an animal study26 researchers found that limiting feeding to 8 hours could protect the mice from obesity, inflammation, liver disease and diabetes, even when they ate the same number of calories during the restricted eight hours as the control group did in 24 hours.

Two days a week — For some it may be easier to restrict intake for an entire 24 hours twice-weekly as opposed to each day. Men may eat up to 600 calories on the fasting days and women up to 500 calories. Typically, the fasting days are separated during the week and you eat normally on the other days.

To use this type of intermittent fasting successfully, there should be at least one nonfasting day between your fasting days. One study27 engaged the participation of 107 overweight or obese women and found this type of fasting reduced insulin levels and improved insulin sensitivity.

Every other day — There are several variations of an every-other-day plan. Some completely avoid solid food and others allow up to 500 calories on fasting days. The authors of one study28 found this type of intermittent fasting was effective for weight loss and heart health for both normal and overweight adults.

Meal skipping — This is a more flexible approach that works well for those who respond to hunger signals and normally eat when they're hungry and skip meals when they're not.

Intermittent fasting achieves metabolic flexibility

The goal of metabolic flexibility is to train your body to use carbohydrates and fat as fuel. The term was first used to describe the capacity of a parasitic worm to generate energy either aerobically or anaerobically, giving it greater versatility to respond and adapt to environmental changes.29

The more current use has been in the context of carbohydrate and fat metabolism in an effort to reduce insulin resistance, a key to metabolic inflexibility that may develop in tissues and organs. Skeletal muscle burns 60% to 80% of glucose in response to insulin, which is thought to be related to the interaction of skeletal muscle and insulin resistance in Type 2 diabetes.30

Insulin resistance is likely part of an overall metabolic inflexibility, which fasting may override. This enhances metabolic flexibility and higher mitochondrial capacity.31 One scientist32 found that insulin resistance comes before metabolic nonalcoholic fatty liver disease (NAFLD), but not in those who experience genetically driven NAFLD.

Another team outlined the factors affecting metabolic flexibility, including diet, eating frequency, exercise and the use of pharmaceuticals.33 Presenters at the American College of Sports Medicine34 conference on Integrative Physiology and Exercise agreed the body's ability to use carbohydrates and fat is vital for optimal health.

In other words, your body's ability to flexibly use fat and carbohydrates for fuel is necessary to reduce insulin resistance, maintain your weight and achieve optimal health.35

Start slow and reap big rewards

If you've never tried intermittent fasting, you may be surprised how easily you may integrate it into your life. I recommend beginning with a 12-hour fast from 7 p.m. until 7 a.m. Once you have achieved this for one week, add one hour every week for a month.

This helps you easily move from a daily 12-hour fast to a 16-hour fast. As you achieve this goal, you may want to consider incorporating alternate strategies described above, depending upon your lifestyle.

There is no one perfect way of practicing intermittent fasting, so experiment until you find one that works for you. The method of starting with 12 hours and moving to a 16-hour fast is one of the best ways I’ve found to reduce your challenges as you integrate intermittent fasting into your nutritional program.

Considerations before you start

Although intermittent fasting is beneficial for many people, there are some points to consider before you begin.

  • Intermittent fasting does not have to be a form of calorie restriction — The practice should make you feel good and help your body to become metabolically flexible. If the strategy you use is making you feel weak and lethargic, reevaluate your approach and try something else.
  • Sugar cravings are temporary — Although some find them initially challenging, your hunger and craving for sugar will slowly go away as your body begins burning fat as its primary fuel. Once your body has successfully shifted to a fat burning mode, it will be easier to fast for up to 18 hours and still feel satisfied.
  • Intermittent fasting is not advisable if your diet is filled with processed foods — Although fasting may sound like a panacea against most health challenges and excess weight, by itself it may not provide you with the benefits you are seeking. The quality of your diet plays an important role in your health.
  • If you have a medical condition, practice fasting under your physician’s care — If you currently have diabetes, are pregnant or under a physician's care for a chronic health condition, it is important you seek the advice of someone who is well-versed in your medical condition as well as intermittent fasting.

If you are interested in using additional, simple strategies to boost your overall health and reduce your dependence on many medications for chronic disease, consider using a KetoFast program. This is a complete system starting with intermittent fasting and a cyclical ketogenic diet, and then moving into a partial fast instead of a water fast.

For more information about the program I discuss in my book, “KetoFast: A Step-by-Step Guide to Timing Your Ketogenic Meals,” see my past article, “Avoid the Dark Side of Fasting and Ketosis With KetoFasting.” There you may hear a podcast with fitness expert Ben Greenfield and discover more about the benefits of fasting.

Avoid eating before bed

Whether you choose to practice intermittent fasting or not, it's important to remember to avoid eating at least three hours before you go to bed. Eliminating this single habit may have positive health repercussions since eating late night meals (when your body does not need the energy) may detrimentally affect your mitochondria.36,37

When your mitochondria receive inappropriate amounts of fuel, even proper fuel, at the wrong time of the day, they may begin to deteriorate and malfunction. Mitochondrial dysfunction lays the groundwork for subsequent breakdowns in a variety of bodily systems leading to chronic illness.38