By Dr. Mercola
It is nice to see the intermittent fasting approach that I have recommended for some time now is starting to catch on. This is no surprise to me as it is one of the most powerful interventions I know of to move your body into fat burning mode and have your hunger nearly magically disappear. It is a powerful tool to help you keep a healthy weight.
In a new diet book, The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting, Dr. Michael Mosley1 suggests the best way to lose weight is to eat normally for five days a week, and fast for two. On fasting days, he recommends cutting your food down to ¼ of your normal daily calories, or about 600 calories for men and about 500 for women, along with plenty of water and tea.
Dr. Mosley himself claims to have lost 19 pounds in two months by following this recommendation. I lost about seven pounds when I implemented the approach last year, but the most amazing aspect is not the weight loss, it’s the absence of hunger and sugar cravings once you are fat adapted. Your desire to eat unhealthy foods seems to disappear; at least that was my experience.
I prefer to think of intermittent fasting as a lifestyle rather than a diet. It’s a way of living and eating that can help you live a longer, healthier life. I promoted the health benefits of intermittent fasting well before it hit the mainstream, and have been experimenting with different types of scheduled eating in my own life for the past two years. I currently restrict my eating to a 6-7 hour window each day.
In the featured BBC interview,2 Dr. Mosley also points out the importance of high-intensity interval training (HIIT) — especially in conjunction with fasting — and how sheer inactivity is actually more detrimental to your health than lack of formal exercise. He recommends getting up every 15-20 minutes if you have a desk job, to avoid the health hazards associated with prolonged sitting. For more helpful tips and recommendations, please see my recent article Sitting Less May be Key for Maximum Longevity, in which I discuss this issue.
HIIT, which is a foundational part of my Peak Fitness Program, is another aspect of optimal health that I’ve been trying to drill into my readers since the mid-2000’s, when the science behind it was showing signs of being really solid. Now the mainstream is finally starting to catch up on this as well, and proof that it really does work as advertised is becoming increasingly evident as people are trying it out.
Intermittent Fasting Becoming Mainstream Health Recommendation
In related news, MSNBC3 recently featured David Zinczenko and Peter Moore, co-authors of yet another book expounding on the health benefits of intermittent fasting:
“Can Americans trim their waistlines by spending less time at the dinner table? In 'The 8-Hour Diet,' best-selling authors David Zinczenko and Peter Moore argue that people can lose weight (and combat our 24-hour eating culture) by only consuming food during a set 8-hour time period.”
This is another version of intermittent fasting, in which you simply restrict your daily eating to a specific window of time. Zinczenko and Moore recommend an eight hour window, which is doable and convenient for most people, but you can restrict it even further — down to six, four, or even two hours, if you want, but you can still reap many of these rewards by limiting your eating to a window of about 8 hours. This means eating only between the hours of 11am until 7pm, as an example. Essentially, this equates to simply skipping breakfast, and making lunch your first meal of the day instead.
It typically takes several weeks to shift to fat burning mode, but once you do, your cravings for unhealthy foods and carbs seems to disappear as you’re now actually able to burn your stored fat and not have to rely on new carbs for fuel.
As discussed in “The 8-Hour Diet”:
“Consider this 2007 American Journal of Clinical Nutrition study: Researchers divided study participants into two groups and had each group eat the same number of calories — enough for them to maintain their weight. The only difference: One group ate all their calories in three meals spread throughout the day, while the other practiced intermittent fasting, eating the same number of calories but in a restricted time frame.
Among the results: Participants who ate in a smaller window of time had a 'significant modification of body composition, including reductions in fat mass.'
Part of that fat burn comes simply from the body’s searching for energy and finding it in your belly. But part of it is also from a surprising source: According to Panda’s research, restricting the time period during which you eat makes your body burn more calories throughout the day. That’s right: The longer you feed, the lazier your metabolism becomes. But fit your food intake into an 8-hour window and your body steps up to the plate, burning more calories day and night. And new evidence shows that weight loss is just the beginning of intermittent fasting’s range of health benefits.”
Keep in mind that the form of fasting that might be best for you will vary depending on your weight, health, and fitness goals. Is your goal to live a longer, healthier life? Or are you a competitive or elite athlete? It may surprise many to learn that you cannot achieve maximum fitness and maximum longevity and fertility at the same time. Each goal requires a different strategy, and will not provide you with equal end results. For example, elite female athletes typically have a difficult time getting pregnant—their fitness has been maximized at the expense of their fertility, as female hormones depend on sufficient amounts of body fat.
Also, please remember that proper nutrition becomes even MORE important when fasting, so addressing the foods you eat really should be your first step. Common sense will tell you that fasting combined with a denatured, highly processed, toxin-rich diet is likely to do more harm than good, as you're not giving your body proper fuel to thrive when you DO eat.
How “Scheduled Eating” Can Promote General Health and Longevity
Aside from removing your cravings for sugar and snack foods, melting the pounds of excess fat away, and making it far easier to maintain a healthy body weight, modern science has also confirmed there are many other good reasons to fast intermittently, such as:
- Normalizing your insulin and leptin sensitivity, which is key for optimal health as insulin resistance (which is what you get when your insulin sensitivity plummets) is a primary contributing factor to nearly all chronic disease, from diabetes to heart disease and even cancer
- Normalizing ghrelin levels, also known as "the hunger hormone"
- Promoting human growth hormone (HGH) production, which plays an important part in health, fitness and slowing the aging process
- Lowering triglyceride levels
- Reducing inflammation and lessening free radical damage
There's also plenty of research showing that fasting has a beneficial impact on longevity in animals. There are a number of mechanisms contributing to this effect. Normalizing insulin sensitivity is a major one, but fasting also inhibits the mTOR pathway, which plays an important part in driving the aging process. The fact that it improves a number of potent disease markers also contributes to fasting's overall beneficial effects on general health.
Interestingly, one recent study4 found that fasting increased the participants' low-density lipoprotein cholesterol (LDL or "bad" cholesterol) and high-density lipoprotein cholesterol (HDL, the "good" cholesterol) by 14 percent and 6 percent, respectively. Why would fasting raise total cholesterol? Dr. Benjamin D. Horne, PhD, MPH, director of cardiovascular and genetic epidemiology at the Intermountain Medical Center Heart Institute, and the study's lead author, offers the following explanation:
"Fasting causes hunger or stress. In response, the body releases more cholesterol, allowing it to utilize fat as a source of fuel, instead of glucose. This decreases the number of fat cells in the body... This is important because the fewer fat cells a body has, the less likely it will experience insulin resistance, or diabetes."
Even more remarkable, the study also found that fasting triggered a dramatic rise in human growth hormone (HGH)—1,300 percent in women, and an astounding 2,000 percent in men! The only other thing that can compete in terms of dramatically boosting HGH levels is high-intensity interval training.
HGH, commonly referred to as "the fitness hormone" plays an important role in maintaining health, fitness and longevity, including promotion of muscle growth, and boosting fat loss by revving up your metabolism. The fact that it helps build muscle while simultaneously promoting fat loss explains why HGH helps you lose weight without sacrificing muscle mass, and why even athletes can benefit from the practice (as long as they don't overtrain and are careful about their nutrition).
Cut Diabetes and Heart Disease Risk Just by Changing WHEN You Eat
In a 2005 study,5 Danish researchers showed that intermittent fasting quickly increases insulin-mediated glucose uptake rates. Eight healthy men in their mid-20’s fasted 20 hours every other day for 15 days. At the end of the trial, their insulin had become more efficient at managing blood sugar.
According to the authors, this appears to confirm the theory of “thrifty genes,” which is similar to Dr. Richard Johnson’s finding that metabolic syndrome is actually a healthy adaptive condition that animals undergo to store fat to help them survive periods of famine. The problem is that most all of us are always feasting and never undergo fasting... Our bodies have not adapted to this yet and as a result, this beneficial adaptation actually causes damage to contemporary man. According to the Danish researchers:6
“Insulin resistance is currently a major health problem. This may be because of a marked decrease in daily physical activity during recent decades combined with constant food abundance. This lifestyle collides with our genome, which was most likely selected in the late Paleolithic era (50,000–10,000 BC) by criteria that favored survival in an environment characterized by fluctuations between periods of feast and famine. The theory of thrifty genes states that these fluctuations are required for optimal metabolic function.
...This experiment is the first in humans to show that intermittent fasting increases insulin-mediated glucose uptake rates, and the findings are compatible with the thrifty gene concept.” [Emphasis mine]
So, by mimicking the natural fluctuations in food availability with an intermittent fasting schedule, you naturally optimize your metabolic function without actually changing what or how much you eat when you DO eat (keeping in mind the quality of the nutrients you eat, of course).
Studies have also found compelling links between fasting and reduced risk of heart disease.7 One of the most recent studies, published in June 2012,8 found that those who fasted regularly had a 58 percent lower risk of coronary disease compared to those who never fasted (90 percent of the participants were Mormons who are encouraged to fast one day a month). Regular fasting was also found to be associated with lower glucose levels and lower body mass index (BMI) overall.
Intermittent Fasting May Also Boost Your Brain Health
A recent article in the Washington Post9 highlighted yet another important health benefit associated with intermittent fasting, namely brain health and protection against dementia. Mark Mattson at the National Institute on Aging told the paper:
“We know from animal models that if we start an intermittent fasting diet at what would be the equivalent of middle age in people, we can delay the onset of Alzheimer’s and Parkinson’s.”
A clue to the mechanism behind this benefit is offered in the following paragraph:10
“A fast is considered to start about 10 to 12 hours after a meal, when you have used up all the available glucose in your blood and start converting glycogen stored in liver and muscle cells into glucose to use for energy. If the fast continues, there is a gradual move toward breaking down stored body fat, and the liver produces 'ketone bodies,' short molecules that are byproducts of the breakdown of fatty acids. These can be used by the brain as fuel.”
Mattson’s research suggests that fasting every other day (restricting your meal on fasting days to about 600 calories), tends to boost production of a protein called brain-derived neurotrophic factor (BDNF) by anywhere from 50 to 400 percent, depending on the brain region. BDNF activates brain stem cells to convert into new neurons, and triggers numerous other chemicals that promote neural health. This protein also protects your brain cells from changes associated with Alzheimer’s and Parkinson’s disease.
“In mice engineered to develop Alzheimer’s-like symptoms, alternate-day fasting begun in middle age delayed the onset of memory problems by about six months,” the Washington Post reveals11. “'This is a large effect,' Mattson says, perhaps equivalent to 20 years in humans.”
Growing evidence indicates that both fasting and exercise trigger genes and growth factors that recycle and rejuvenate your brain and muscle tissues. These growth factors include BDNF, as just mentioned, and muscle regulatory factors, or MRFs. These growth factors signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells respectively.
Interestingly enough, BDNF also expresses itself in the neuro-muscular system where it protects neuro-motors from degradation. (The neuromotor is the most critical element in your muscle. Without the neuromotor, your muscle is like an engine without ignition. Neuro-motor degradation is part of the process that explains age-related muscle atrophy.) So BDNF is actively involved in both your muscles and your brain, and this cross-connection, if you will, appears to be a major part of the explanation for why a physical workout can have such a beneficial impact on your brain tissue—and why the combination of intermittent fasting with high intensity exercise appears to be a particularly potent combination.
Give Intermittent Fasting a Try
Consider skipping breakfast eat lunch and dinner and make sure you stop eating three hours before you go to sleep, so you’re eating within an 8-hour time frame every day. In the 6-8 hours that you do eat, you want to have healthy protein, minimize your carbs like pasta and bread and potatoes and exchange them for HEALTHY fats like butter, eggs, avocado, coconut oil, olive oil and nuts. The type of fats the media and “experts" tell you to avoid.
This will help shift you to fat burning mode from carb burning mode. Remember it takes a few weeks, and you have to do it gradually, but once you succeed to switch to fat burning mode, you will be easily able to fast for 18 hours and not feel hungry. Your cravings for sugar will magically disappear and it will be much easier to achieve your ideal weight.
The other “magical” benefit that occurs is that you will radically improve the beneficial bacteria in your gut. Why is this a good thing? Because supporting healthy gut bacteria, which actually outnumber your cells 10 to one—is one of the most important things you can do to improve your immune system so you won’t get sick, or get coughs, colds and flus. You will sleep better, have more energy, have increased mental clarity and concentrate better. Essentially every aspect of your health will improve.
Hopefully these new books and studies, along with my own pleasant experience and positive results with intermittent fasting will encourage you to give it a try. It’s another powerful tool to help you and your family take control of your health.