I don’t like the feeling of being hungry. I don’t think anyone does. I don’t need to lose weight. The evidence about fasting is thin to say the least. So why do I fast several times a week?
Basically, I am interested in improving my health. I am a long-term cancer survivor living with a host of side effects and a risk of relapse and/or treatment-related secondary cancer. So I exercise moderatly, eat lots of fruits and veggies, detox through whole-body hyperthermia and generally look for easy yet healthy lifestyle therapies.
I don’t consider keeping my eating to a 12 hour period each day to be all that difficult. I do this because of articles like the one’s linked and excerpted below. And the 12:12 fast is certainly not a “miracle.”
But if by keeping my eating to a 12 hour period helps me keep the pounds off and if keeping the pounds off keeps me cancer-free (I am a cancer survivor BTW) then I will add this lifestyle therapy to my long and growing list of anti-cancer lifestyle therapies.
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Result: Mice that fasted at least 12 hours gained less weight overall than mice that were fed the same type and amount of food but had the run of the feed through all 24 hours. Even when the fasters got free “weekend passes” to gorge anytime, in the end they still put on fewer pounds (OK, grams) than the nonstop nibblers. And when non-fasting obese mice were put on the 12-hour fast, they dropped 5% of their body weight—though they were eating the same calories!\..”
“…The counterintuitive observation that underfeeding animals can lengthen their lives is an old one. In 1935, scientist Clive McCay conducted a simple experiment: One group of lab rats was allowed to eat as much as they desired while the other was given a calorie-restricted diet. The result was dramatic and undeniable. Rats from the second group lived significantly longer than rats from the first group.
Since this pioneering work, the basic thrust of McCay’s finding has been repeated again and again all over the tree of life. In yeast, flies, worms, fish, mice, rats and monkeys, hunger appears to be the fountain of youth. The findings have been replicated with fasting diets as well. Ever since researchers in the 1990s found that mice fed every other day outlived mice that fed every day, evidence has poured in that fasting can increase the life spans of animals. The message seemed clear: Give one group of creatures more, give another group less, and the latter outlives the former
Less is more, it seems—up until it isn’t. “Of course, it has to be optimized,” says Rozalyn Anderson, a professor at the University of Wisconsin. “The less you eat the longer you live, up until the point when you start doing damage. If you continue to eat less, well then you are going to die.”
As a recent fasting study in flies illustrates, striking this optimal balance is a difficult task. James Catterson of the Institute of Healthy Ageing at University College London walked me through the process by which he and his colleagues zeroed in on a successful fasting regimen. First, he tried depriving the flies of food for three to six hours a day and found no measurable effect. Next, he tried fasting for two consecutive days each week. Nothing. Three days? Nothing. Four days? Nothing. Upping the ante to five days seemed ridiculous, but Catterson tried it anyway. Finally, there was an effect, but it was a frustrating one: The fasting flies had shorter life spans than the controls. At this point, Catterson says he was ready to quit. In a last-ditch effort, he tried a slight tweak: a five-days-a-week fast during the first 30 days, followed by constant food for the remainder of their lives. This seemed to be the secret sauce—at last, the fasting flies lived significantly longer.
It took Catterson several years and many generations of fruit flies to find a successful fasting regimen. This “guess and check” strategy isn’t a viable approach for research on humans, though, for a plethora of practical and ethical reasons. A fruit fly can now thank the countless martyrs of Catterson’s research to live a longer, healthier life through fasting. But what about us? “We definitely wouldn’t recommend a five-day water-only fast in humans!” says Catterson, stating the obvious. “One of the main things I would stress is that due to the infancy of research into intermittent fasting … there is no method that anyone should necessarily be recommending, for the moment.” When I asked Anderson whether she practiced calorie restriction or would feel comfortable recommending it to someone else, her response was unequivocal: “No and no.”
Not all researchers are as cautious. Mark Mattson, chief of the laboratory of neurosciences at the National Institute on Aging, says that he practices a fasting regimen known as time-restricted feeding. “I don’t eat breakfast, work out midday, and then I’ll eat over a period of 6 hours. … That’s been my normal routine for quite a while.” At first glance, this routine resembles what Muslims do during the month of Ramadan: eat during a narrow window of the day, fast for the remainder. However, Mattson’s feelings about Ramadan fasting were mixed—refraining from water during the day concerned him. He also noted that many Muslims actually gain weight during Ramadan due to overeating at night. “That’s not good!” he exclaims. “During the month of Ramadan, one would almost surely accrue health benefits if one did not overeat.”
When I mention that the Prophet Mohammad was believed to have fasted two days a week, Mattson jokes: “Clearly, Mohammad was ahead of his time!” Mattson and his colleagues showed in 2011 that two days of fasting per week resulted in weight loss, decreased cholesterol, lower blood pressure, and other health benefits in young, overweight women. This original “5:2” regimen remains a widely popular diet today, followed by the likes of Benedict Cumberbatch, Jennifer Metcalfe, and Jimmy Kimmel.
Mattson seems optimistic that fasting will one day be generally embraced. “I think it’s going to take quite a while to get actual clinical practice and recommendations caught up with the times, but I think it will.” There has always been a heavy burden of proof on dietary research. As a point of comparison, the “Mediterranean diet” has long been recommended by physicians (and yes, there was a recent controversy around a retraction on this diet, but its generally efficacy is still widely agreed-upon). The PREDIMED trial, the seminal study supporting the Mediterranean diet, followed some 7,500 patients over the course of nearly five years. Over 250 studies citing the PREDIMED trial have found the Mediterranean diet to effectively curb obesity, diabetes, cardiac disease, and more. By contrast, the cleverly acronymed CALERIE clinical trial, the largest calorie-restriction study in humans to date, followed just 200 patients over the course of two years. Similarly, the largest fasting study followed 100 women for six months. The vast majority of calorie restriction and fasting studies only involve a dozen or so individuals. While many of these studies suggest that calorie restriction and fasting promote general health and curb most age-related diseases in humans, the sample sizes are simply too small to garner widespread support from physicians.
But to me, the study that matters the most is much smaller than any of these: my own experiences (n = 1). I’ll never get to know whether my own life was lengthened or shortened by virtue of fasting. Although I’ve been fortunate not to have any serious health problems, I’ll never be able to pin that precisely on Ramadan: maybe diet, exercise, or plain luck deserve the credit. I’ll never get to probe that counterfactual world of “What if?” What I can say is that I am different during the month of Ramadan. In this month, I feel my mind and heart at peace. Nearly every night I enjoy the blessing of eating dinner with other people. As a result, my friends and my family feel close during these 30 days. Every night when I break fast, I am reminded of my good fortune. Aware of the luxury to choose when and when not to eat, my gratitude grows. And yes, for those who care, I dependably lose 8 pounds.”
“Daily fasting is an effective tool to reduce weight and lower blood pressure, according to a new study published by University of Illinois at Chicago researchers in the journal Nutrition and Healthy Aging.The study is the first to examine the effect of time-restricted eating—a form of fasting that limits food consumption to select hours each day—on weight loss in obese individuals.
To study the effect of this type of diet, researchers worked with 23 obese volunteers who had an average age of 45 and average body mass index, or BMI, of 35.
Between the hours of 10 a.m. and 6 p.m. the dieters could eat any type and quantity of food they desired, but for the remaining 16 hours they could only drink water or calorie-free beverages. The study followed the participants for 12 weeks.
When compared to a matched historical control group from a previous weight loss trial on a different type of fasting, the researchers found that those who followed the time-restricted eating diet consumed fewer calories, lost weight and had improvements in blood pressure. On average, participants consumed about 350 fewer calories, lost about 3 percent of their body weight and saw their systolic blood pressuredecreased by about 7 millimeters of mercury (mm Hg), the standard measure of blood pressure. All other measures, including fat mass, insulin resistance and cholesterol, were similar to the control group.
“The take-home message from this study is that there are options for weight loss that do not include calorie counting or eliminating certain foods,” said Krista Varady, associate professor of kinesiology and nutrition in the UIC College of Applied Health Sciences and corresponding author on the study.
“Not eating in the evening and at night could reduce the risk for recurrence of breast cancer, according to a new study published online March 31 in JAMA Oncology.
In a cohort of 2400 women with early-stage breast cancer, researchers found that fasting less than 13 hours per night was associated with a 36% higher risk for disease recurrence as compared with fasting 13 or more hours per night.
A nonsignificant 22% higher risk for mortality from any cause was also observed among patients who fasted for shorter periods in comparison with those who fasted for 13 hours or more overnight.
“Prolonging the overnight fasting interval may be a simple, nonpharmacological strategy for reducing a person’s risk of breast cancer recurrence and even other cancers,” said first author Catherine Marinac, a doctoral candidate at Moores Cancer Center, University of California, San Diego (UCSD), in a statement.
“Previous research has focused on what to eat for cancer prevention, but when we eat may also matter, because it appears to affect metabolic health,” she said.
The authors also found that fasting fewer hours per night was associated with significantly less sleep and higher levels of glycated hemoglobin (HbA1c).
These findings are relevant to cancer prevention and control efforts, they note, inasmuch as elevated levels of HbA1c and poor sleeping habits have been linked to an increased risk for breast cancer…
The researchers found that fasting less than 13 hours per night was associated with an increase in the risk for breast cancer recurrence compared with fasting 13 or more hours per night (hazard ratio, 1.36).
However, there was no effect on deaths, either from breast cancer or from all causes. Fasting less than 13 hours was not associated with a statistically significant higher risk for breast cancer mortality (hazard ratio, 1.21) or a statistically significant higher risk for all-cause mortality (hazard ratio, 1.22).
Each 2-hour increase in nightly fasting duration was statistically significantly associated with a 0.37 mmol/mol lower HbA1c level (β = –0.37) and more hours of sleep per night (β = 0.20).