By Dr. Mercola
According to research1 published in 2015, 52 percent of Americans are presently either prediabetic or diabetic. A hallmark symptom of both is insulin and leptin resistance, a situation in which your body can no longer "hear" the signals from these important energy-regulating hormones.
According to Dr. Robert Lustig, when an organ becomes insulin resistant, it manifests as chronic metabolic disease.
For example, when you have insulin resistance of the liver, you end up with type 2 diabetes; insulin resistance of the brain results in Alzheimer's disease; insulin resistance of the kidney leads to chronic renal disease, and so on.
Inactivity Is a Significant Risk Factor for Insulin Resistance
Insulin resistance also increases your risk of obesity, although one-third of slim Americans also have prediabetes,2 so absence of obesity is no guarantee of health. Rather, inactivity (being active less than 30 minutes per week) is the primary risk factor for insulin resistance.
One of the forerunners who helped impress the importance of non-exercise movement was Joan Vernikos,3 Ph.D., former director of NASA's Life Sciences Division and author of "Sitting Kills, Moving Heals." I am doing an update with her later this year.
In the video below, she presents a scientific explanation for why sitting has such a dramatic impact on your health, and the common-sense solution.
Dr. James Levine, co-director of the Obesity Initiative for Mayo Clinic and author of "Get Up! Why Your Chair Is Killing You and What You Can Do About It," is another leading expert on this topic.
As noted by Levine, prolonged sitting is an independent risk factor for chronic disease and premature death — even if you exercise regularly and stay fit.
The reason for this is because sitting shuts down or blocks a number of insulin-mediated systems, including muscular and cellular systems that process blood sugar, triglycerides and cholesterol. Standing up, bearing your own body weight on your legs, activates all of these systems at the molecular level.
Studies Highlight Importance of Exercise for Diabetics
I've often stated that exercise is an important prevention strategy for type 2 diabetes, and three recent studies have highlighted this point.4 Specifically, the studies confirm that the timing and quantity of exercise play a significant role, and that chronic sitting is particularly hazardous for those with diabetes.
The first study,5 conducted by researchers in New Zealand, found that taking a 10-minute walk after each meal provided greater blood sugar control in diabetics than 30 minutes of exercise done once a day, lowering post-meal blood sugar levels by 22 percent. So, increasing the frequency of movement is an important component.
The second study6 was a scientific review of 28 studies, which showed an inverse relationship between exercise and overall diabetes risk.
In other words, the more you exercise, the lower your risk of type 2 diabetes. They also concluded that one of the primary mechanisms is that exercise allows your muscles to use sugar more effectively.
Increasing exercise from 150 minutes to 300 minutes per week reduced the risk of type 2 diabetes by 36 percent. Unfortunately, data7 from the Centers for Disease Control and Prevention (CDC) suggests less than half of Americans get even 150 minutes of exercise per week, so there's plenty of room for improvement.
Diabetics Need to Move More Throughout the Day
A third study,8 done by Australian researchers, found type 2 diabetics who sit all day (rising only for bathroom breaks) have much riskier blood fat profiles than those who get up and move for three minutes every 30 minutes.
Lead author Megan Grace, Ph.D., and senior research officer at Baker Heart and Diabetes Institute in Melbourne, told Reuters:9
"We have previously shown that interrupting prolonged sitting with light intensity activity after meals reduces risk factors for heart disease and diabetes, such as elevated blood sugars and high blood pressure. What we found interesting about this study was that breaking up sitting also reduces levels of lipids (fats) in the bloodstream that are associated with risk for type 2 diabetes and its complications.
Our study showed that breaks which include either simple resistance exercise or light walking were generally equally beneficial in reducing blood lipids. Our current findings reinforce the message that avoiding prolonged periods of sitting, and finding ways to increase activity across the day, is beneficial for health.
In line with the recent American Diabetes Association Position Statement, we recommend interrupting sitting every 30 minutes with a few minutes of light intensity activity, in addition to regularly taking part in a structured exercise program … Stand up, sit less, and move more — particularly after meals."
Exercise Benefits Type 1 Diabetics as Well
Type 1 diabetics, who are insulin-dependent as their pancreas produces no insulin, also stand to gain a great deal from exercise. In a small study performed over three months, researchers monitored the effect aerobic exercise had on individuals with type 1 diabetes.10
Participants who included aerobic exercise in their daily activities enjoyed better metabolic control and lower insulin requirements throughout the day. That said, exercising with type 1 diabetes does present unique challenges. In the video above, a young man named Jason talks about what it's like to be a competitive cyclist with type 1 diabetes.
Before starting an exercise program, it's important to do your homework. If you don't already, use a daily diary to record your food intake, insulin use, blood glucose levels and current exercise habits. Watch for consistent changes in your glucose levels with the number of carbs, protein and fats you eat, in combination with your current exercise level.
You'll use this to help predict your glucose levels as you begin to increase your aerobic exercise. Always exercise with a partner. A precipitous drop in blood glucose can be lethal. It's safer to exercise with someone who can recognize the symptoms of low blood sugar and is able to treat your symptoms appropriately.
Choose aerobic exercises that meet your current physical fitness abilities, and remember to include those activities you might not consider aerobic exercise, but which may impact your blood sugar levels, such as gardening, gentle walking or dancing.
Ketogenic Diet Improves Insulin Sensitivity and Lowers Inflammation
Another important strategy that can prevent or even reverse insulin resistance and/or type 2 diabetes is nutritional ketosis. It can also have a dramatic impact on your weight, finally allowing you to shed unwanted pounds, as your body begins to burn fat as its primary fuel. In short, by optimizing your metabolic and mitochondrial function, nutritional ketosis helps set you squarely on the path to better health.
In fact, emerging evidence suggests a high-fat, low-net carb, low- to moderate-protein diet (in other words, a diet that keeps you in nutritional ketosis) is ideal for most people. Even endurance athletes are turning away from conventional high-carb strategies and adopting this way of eating because it boosts physical stamina and endurance. Beyond insulin resistance and type 2 diabetes, there are a number of applications for nutritional ketosis, including the following:
- As a treatment for seizures and neurological conditions such as Alzheimer's and Parkinson's
- Hormone regulation; polycystic ovary syndrome
- Nervous system disorders such as multiple sclerosis
How to Enter Into Nutritional Ketosis
The most efficient way to train your body to use fat for fuel is to remove most of the sugars and starches (net carbs) from your diet. At the same time, you'll want to replace those carbs with healthy fats. I explain the ins and outs of implementing this kind of diet, and its many health benefits, in my new book "Fat for Fuel."
As a general guideline, a dietary intake of about 20 to 50 grams or even less per day of net carbs (total carbohydrates minus fiber) while also keeping protein low-to-moderate is usually low enough to allow you to make the shift to nutritional ketosis (the metabolic state associated with an increased production of ketones in your liver; i.e., the biological reflection of being able to burn fat).
However, each person responds to foods in a different way. Some people can enter into full ketosis while eating as much as 70 to 80 grams of non-fiber carbs. Others, especially if you're insulin resistant or have type 2 diabetes, may require less than 40 grams, or even as little as 30 grams per day, to get there.
To find your personal carb target, it's important to measure not just your blood glucose but also your ketones, which can be done either through urine, breath or blood. This will give you an objective measure of whether or not you're truly in ketosis. Nutritional ketosis is defined as blood ketones that stay in the range of 0.5 to 3.0 millimoles per liter (mmol/L).
That said, using a nutrient tracker will radically improve your ability to understand precisely the macronutrient composition of the foods you eat, and will help you to keep to your ketogenic diet nutrient targets. My first choice is Cronometer.com/mercola. That's my upgrade to the basic Cronometer nutrient tracker, and the default is set to macronutrient levels that will support nutritional ketosis.
The Importance of Cycling In and Out of Ketosis
An oft-ignored component of nutritional ketosis is the importance of cycling through stages of feast and famine, opposed to continuously remaining in nutritional ketosis. Nutritional ketosis is a powerful intervention, but if you do it continuously, it can actually be counterproductive.
You need to have days where you eat more net carbs and more protein, especially with strength training, to prevent sarcopenia. The "metabolic magic" actually occurs during that refeeding phase when net carbs and protein are increased, which increases muscle growth. After a day or two, you then cycle back into nutritional ketosis. Typically, this is done once a week.
Should You Use a Glucose Monitor if You're Not Diabetic?
As noted in a recent Time Magazine article,11 many healthy people are now starting to wear 24-hour continuous glucose monitors, myself included. In the video above, I talk with Dr. Daniel Pompa about the benefits of doing this.12
One of the reasons I wear the glucose monitor is because it helps me to fine-tune my Peak Fasting regimen — an intermittent fasting program that involves fasting for at least 12 hours, ideally eating your last meal at least three hours before bed, to avoid generating excessive reactive oxygen species.
In addition to eating a ketogenic diet, Peak Fasting is another important strategy that can help prevent or reverse diabetes and other chronic disease, as this kind of eating schedule really helps kick start your metabolism to burn fat rather than sugar. This too is discussed at length in my new book, "Fat for Fuel."
When I wrote the book, I used a Dexcom monitor.13 You insert a sensor beneath your skin for a week, which then takes continuous glucose readings every five minutes. It really helped me fine-tune and evaluate how different foods impacted my glucose levels.
This tool helped me understand the importance of feast-famine cycling. In other words, I strongly believe one should not be on a ketogenic diet long-term, even if you have cancer. You remain on it only long enough for your body to burn fat for fuel and then you have 1 to 2 days a week of higher carb and protein intake, and cycle back to ketogenic the other days.
Type 2 Diabetes Is Preventable and Reversible
I've often said that type 2 diabetes is easily preventable, and nearly 100 percent reversible. Four key lifestyle strategies to accomplish this are exercise (ideally including some high-intensity interval training once you're able), non-exercise movement throughout each day, a whole food-based ketogenic diet and Peak Fasting.
The intermittent fasting need not be a lifelong endeavor. Once you've normalized your condition, you can stop. Also remember that cycling through periods of "feast and famine" is typically more effective than remaining in nutritional ketosis indefinitely. That said, a ketogenic diet is really more of a lifestyle than a "diet."
Returning to a processed food diet chockfull of net carbs and few healthy fats will eventually put you right back where you started. If you are exceptionally overweight then please consider water fasting as discussed in my interview with nephrologist Dr. Jason Fung.
As for physical movement, research suggests standing and moving about as much as possible during the day may be even more important than having a regular exercise regimen, although the latter will surely optimize your health and fitness in ways non-exercise movement cannot so, ideally, do both.