Intermittent Fasting club

Thanks for this, Flyer. Chia seeds are new to me - I have a packet of them, but haven't got around to cooking with them yet, so this can spur me on. :)
bagels are my kryptonite, so now when i have one just toasted, i sprinkle on some flax or chia seeds to help with the fiber inherently missing from bagels. watch cooking with seeds... in the recipe for those seed-based crackers i've been making, they reference excessive heat as being harmful to some nutritional aspect of seeds, but i'm not at all knowledgeable about what they were talking about. i have mixed some flax seeds into ground beef and made burgers.
Omega 3 fatty acids don´t stand up to heat, if I remember correctly. Also: don´t forget to bruise/grind and/or soak chia and flax (soaking for several hours) before use to help your body get to the nutrients.
still mortar and pestless, but working on it... there is an all granite version i have my eye on.

occurred to me on my shopping trip this morning how much my habits have changed. i remember always hearing, "never go shopping when you're hungry". well, that's not very easy on an intermittent fasting schedule, especially since i prefer shopping early in the morning... even before it's become a more healthy time to shop... at least according to my logic.

but here it is... after 10am, ... my last meal was about 14 hours ago... the house is full of food, albeit nothing i can merely pop open a bag of... ok, i must admit my mind is trying to work out a menu for later on, but right now it often surprises me that i'm not hungry at times like this.

...go figure.
i'm sure i've mentioned this other places, but it's worth repeating. on paper intermittent fasting might sound easy... but in reality, hunger is something you have to learn to deal with. i intermittent fast... maybe 90% of my days now. days i do not include a typical IF fasting time of, say, 16-18 hours, i always go without eating at least 12-14 hours. anyone trying to start an intermittent fast should probably shoot for that goal. even including sleep, with late night snacking and grabbing that muffin first thing in the morning, i'm sure most people don't even go 12 hours (something Dr. Fung mentions in ^^^^^ that video).

i'm not sure if it gets easier or if i'm just used to it, but i put up with a few hunger episodes daily. they fade, though. sometimes i think i can predict them, but often they merely come and go. with some people it will be a certain time after their last meal (this seems to be my case... often) and with some it is triggered by a time of day... it's noon... i should eat, etc.

not sure there is any one solution for everyone. and just to throw this one in... i have done a few multi-day fasts (3 days is my max) and believe it or not, the 2nd day is a lot easier than the 1st. strange, but true.
to clarify, the following is only directed at those trying to lose weight through IF... maintenance is a bit different.

i think i can say this pretty much from my own experience at this point... i believe i've figured out why the rate of weight loss goes down as you get closer to a healthy (or a healthier) BMI. your body will take every chance you give it to stick some fat on you. to your body fat is "money in the bank". you can't be good 60% of the time or 70% of the time or even 85.7% of the time ( <--- cheating one day a week).

if you cannot follow your rules 100% of the time, i'll go as low as 96.7% (1 day in 30) ... nobody doesn't screw up once a month. on a more positive note, i am still convinced that the best way to control your weight and improve your health is through any of the many forms of fasting. i don't know of any machine that doesn't run better by dialing it down now and then.
had to do a double take this morning... did Jenny Craig just mention Intermittent Fasting in one of her commercials...?
from Healthy Habits... a Jenny Craig Blog...
Time-Restricted Eating vs. Intermittent Fasting

i don't know if they get it 100% right... there is a lot more attention paid on "front loading" your daily meals vs the other outcome of this practice... DON'T EAT AT NIGHT RIGHT UP UNTIL YOU FALL ASLEEP.

this is one of the references cited by JC ... a little more on topic.

interesting that Circadian Rhythms is brought into play... do we eat into the evening and the middle of the night because we have the ability to turn on a light and easily find food? given the span of human existence, you can't help but notice this is a relatively new innovation.
Fasting, Circadian Rhythms, and Time-Restricted Feeding in Healthy Lifespan
thought i would comment on "front loading" your daily caloric intake since i did that occasionally... but not anymore.

the idea, as far as i can fathom, is to eat most of your carbs well before your last meal of the day. they stress lunch as the "big meal" giving plenty of time for the carbs, which trigger the largest insulin spike, to settle down. dinner, emphasizing fat and protein, will lessen the evening crash that leads to nighttime snacking. i wish they would emphasize more that it is the elimination of evening snacking that is the major goal, though i would agree that this plan might make that goal easier to meet.

the other disagreement i have is the insistence that breakfast (and i assume most people actually mean MORNING breakfast) not be skipped, although an indication was made that it could be delayed a "few hours". the insanity (as far as i can see) is that the suggestion is to have ~300 calories meal. why on earth would you break your fast for such a piddling amount of food... just enough to stop the benefit of, at this point of the day, typically 12 hours of fasting assuming you have stopped eating with dinner the previous day. if you do this, you are missing out on the benefit of 14-16 hours of fasting while you completely stop the fat burning cycle. that 300 calories will get you to lunch, but so would your stored fat if you kept the evening fasting mode up until "traditional lunch"... which would now become your breakfast meal.

other than skipping breakfast, i do essentially believe in getting carbs out of the way early in the day, but personally i find that eating a light breakfast (at around noon) is the best way to come off my evening fasting hours. the tendency (even with me sometimes) is to attack food after the evening fast, but i do much better with a small portion of something when my eating window starts, ... then i will immediately take a break for an hour or so before i eat anything else. not saying this would work for everyone, but it certainly works for me. the other benefit of eating a small-ish first meal of the day... sometimes my eating window is only 5-6 hours... if i eat a lot in the first hour, it's hard for me to get an appetite before the window closes.

my best advice... find out what works for you while still following the basic IF rules.
every time i see an article like this, it increases my resolve.
this is one of the articles referenced in the publication noted above.
if anyone can find/ cite a negative opinion on Intermittent Fasting, i'd certainly like to see it.
(i added the bolded text + a rather technical discussion of the effect of IF on certain chronic conditions isn't included.)


Effects of Intermittent Fasting on Health, Aging, and Disease
Rafael de Cabo, Ph.D., and Mark P. Mattson, Ph.D.

According to Weindruch and Sohal in a 1997 article in the Journal, reducing food availability over a lifetime (caloric restriction) has remarkable effects on aging and the life span in animals. The authors proposed that the health benefits of caloric restriction result from a passive reduction in the production of damaging oxygen free radicals. At the time, it was not generally recognized that because rodents on caloric restriction typically consume their entire daily food allotment within a few hours after its provision, they have a daily fasting period of up to 20 hours, during which ketogenesis occurs. Since then, hundreds of studies in animals and scores of clinical studies of controlled intermittent fasting regimens have been conducted in which metabolic switching from liver-derived glucose to adipose cell–derived ketones occurs daily or several days each week. Although the magnitude of the effect of intermittent fasting on life-span extension is variable (influenced by sex, diet, and genetic factors), studies in mice and nonhuman primates show consistent effects of caloric restriction on the health span.

Studies in animals and humans have shown that many of the health benefits of intermittent fasting are not simply the result of reduced free-radical production or weight loss. Instead, intermittent fasting elicits evolutionary conserved, adaptive cellular responses that are integrated between and within organs in a manner that improves glucose regulation, increases stress resistance, and suppresses inflammation. During fasting, cells activate pathways that enhance intrinsic defenses against oxidative and metabolic stress and those that remove or repair damaged molecules. During the feeding period, cells engage in tissue-specific processes of growth and plasticity. However, most people consume three meals a day plus snacks, so intermittent fasting does not occur.

Preclinical studies consistently show the robust disease-modifying efficacy of intermittent fasting in animal models on a wide range of chronic disorders, including obesity, diabetes, cardiovascular disease, cancers, and neurodegenerative brain diseases. Periodic flipping of the metabolic switch not only provides the ketones that are necessary to fuel cells during the fasting period but also elicits highly orchestrated systemic and cellular responses that carry over into the fed state to bolster mental and physical performance, as well as disease resistance.

Here, we review studies in animals and humans that have shown how intermittent fasting affects general health indicators and slows or reverses aging and disease processes. First, we describe the most commonly studied intermittent-fasting regimens and the metabolic and cellular responses to intermittent fasting. We then present and discuss findings from preclinical studies and more recent clinical studies that tested intermittent-fasting regimens in healthy persons and in patients with metabolic disorders (obesity, insulin resistance, hypertension, or a combination of these disorders). Finally, we provide practical information on how intermittent-fasting regimens can be prescribed and implemented.

Intermittent Fasting and Metabolic Switching

Glucose and fatty acids are the main sources of energy for cells. After meals, glucose is used for energy, and fat is stored in adipose tissue as triglycerides. During periods of fasting, triglycerides are broken down to fatty acids and glycerol, which are used for energy. The liver converts fatty acids to ketone bodies, which provide a major source of energy for many tissues, especially the brain, during fasting. In the fed state, blood levels of ketone bodies are low, and in humans, they rise within 8 to 12 hours after the onset of fasting, reaching levels of 0.2 to 0.5 mM, which are maintained through 24 hours, with a subsequent increase to 1 to 2 mM by 48 hours. In rodents, an elevation of plasma ketone levels occurs within 4 to 8 hours after the onset of fasting, reaching millimolar levels within 24 hours. The timing of this response gives some indication of the appropriate periods for fasting in intermittent-fasting regimens.

In humans, the three most widely studied intermittent-fasting regimens are alternate-day fasting, 5:2 intermittent fasting (fasting 2 days each week), and daily time-restricted feeding. Diets that markedly reduce caloric intake on 1 day or more each week (e.g., a reduction to 500 to 700 calories per day) result in elevated levels of ketone bodies on those days. The metabolic switch from the use of glucose as a fuel source to the use of fatty acids and ketone bodies results in a reduced respiratory-exchange ratio (the ratio of carbon dioxide produced to oxygen consumed), indicating the greater metabolic flexibility and efficiency of energy production from fatty acids and ketone bodies.

Ketone bodies are not just fuel used during periods of fasting; they are potent signaling molecules with major effects on cell and organ functions. Ketone bodies regulate the expression and activity of many proteins and molecules that are known to influence health and aging. These include peroxisome proliferator–activated receptor γ coactivator 1α (PGC-1α), fibroblast growth factor 21, nicotinamide adenine dinucleotide (NAD+), sirtuins, poly(adenosine diphosphate [ADP]–ribose) polymerase 1 (PARP1), and ADP ribosyl cyclase (CD38). By influencing these major cellular pathways, ketone bodies produced during fasting have profound effects on systemic metabolism. Moreover, ketone bodies stimulate expression of the gene for brain-derived neurotrophic factor, with implications for brain health and psychiatric and neurodegenerative disorders.

How much of the benefit of intermittent fasting is due to metabolic switching and how much is due to weight loss? Many studies have indicated that several of the benefits of intermittent fasting are dissociated from its effects on weight loss. These benefits include improvements in glucose regulation, blood pressure, and heart rate; the efficacy of endurance training; and abdominal fat loss.

Intermittent Fasting and Stress Resistance

In contrast to people today, our human ancestors did not consume three regularly spaced, large meals, plus snacks, every day, nor did they live a sedentary life. Instead, they were occupied with acquiring food in ecologic niches in which food sources were sparsely distributed. Over time, Homo sapiens underwent evolutionary changes that supported adaptation to such environments, including brain changes that allowed creativity, imagination, and language and physical changes that enabled species members to cover large distances on their own muscle power to stalk prey.

The research reviewed here, and discussed in more detail elsewhere, shows that most if not all organ systems respond to intermittent fasting in ways that enable the organism to tolerate or overcome the challenge and then restore homeostasis. Repeated exposure to fasting periods results in lasting adaptive responses that confer resistance to subsequent challenges. Cells respond to intermittent fasting by engaging in a coordinated adaptive stress response that leads to increased expression of antioxidant defenses, DNA repair, protein quality control, mitochondrial biogenesis and autophagy, and down-regulation of inflammation. These adaptive responses to fasting and feeding are conserved across taxa. Cells throughout the bodies and brains of animals maintained on intermittent-fasting regimens show improved function and robust resistance to a broad range of potentially damaging insults, including those involving metabolic, oxidative, ionic, traumatic, and proteotoxic stress. Intermittent fasting stimulates autophagy and mitophagy while inhibiting the mTOR (mammalian target of rapamycin) protein-synthesis pathway. These responses enable cells to remove oxidatively damaged proteins and mitochondria and recycle undamaged molecular constituents while temporarily reducing global protein synthesis to conserve energy and molecular resources. These pathways are untapped or suppressed in persons who overeat and are sedentary.
...part 2.

Effects of Intermittent Fasting on Health and Aging

Until recently, studies of caloric restriction and intermittent fasting focused on aging and the life span. After nearly a century of research on caloric restriction in animals, the overall conclusion was that reduced food intake robustly increases the life span.

In one of the earliest studies of intermittent fasting, Goodrick and colleagues reported that the average life span of rats is increased by up to 80% when they are maintained on a regimen of alternate-day feeding, started when they are young adults. However, the magnitude of the effects of caloric restriction on the health span and life span varies and can be influenced by sex, diet, age, and genetic factors.7 A meta-analysis of data available from 1934 to 2012 showed that caloric restriction increases the median life span by 14 to 45% in rats but by only 4 to 27% in mice. A study of 41 recombinant inbred strains of mice showed wide variation, ranging from a substantially extended life span to a shortened life span, depending on the strain and sex. However, the study used only one caloric-restriction regimen (40% restriction) and did not evaluate health indicators, causes of death, or underlying mechanisms. There was an inverse relationship between adiposity reduction and life span suggesting that animals with a shortened life span had a greater reduction in adiposity and transitioned more rapidly to starvation when subjected to such severe caloric restriction, whereas animals with an extended life span had the least reduction in fat.

The discrepant results of two landmark studies in monkeys challenged the link between health-span extension and life-span extension with caloric restriction. One of the studies, at the University of Wisconsin, showed a positive effect of caloric restriction on both health and survival, whereas the other study, at the National Institute on Aging, showed no significant reduction in mortality, despite clear improvements in overall health. Differences in the daily caloric intake, onset of the intervention, diet composition, feeding protocols, sex, and genetic background may explain the differential effects of caloric restriction on life span in the two studies.

In humans, intermittent-fasting interventions ameliorate obesity, insulin resistance, dyslipidemia, hypertension, and inflammation. Intermittent fasting seems to confer health benefits to a greater extent than can be attributed just to a reduction in caloric intake. In one trial, 16 healthy participants assigned to a regimen of alternate-day fasting for 22 days lost 2.5% of their initial weight and 4% of fat mass, with a 57% decrease in fasting insulin levels.34 In two other trials, overweight women (approximately 100 women in each trial) were assigned to either a 5:2 intermittent-fasting regimen or a 25% reduction in daily caloric intake. The women in the two groups lost the same amount of weight during the 6-month period, but those in the group assigned to 5:2 intermittent fasting had a greater increase in insulin sensitivity and a larger reduction in waist circumference.

Physical and Cognitive Effects of Intermittent Fasting

In animals and humans, physical function is improved with intermittent fasting. For example, despite having similar body weight, mice maintained on alternate-day fasting have better running endurance than mice that have unlimited access to food. Balance and coordination are also improved in animals on daily time-restricted feeding or alternate-day fasting regimens. Young men who fast daily for 16 hours lose fat while maintaining muscle mass during 2 months of resistance training.

Studies in animals show that intermittent fasting enhances cognition in multiple domains, including spatial memory, associative memory, and working memory; alternate-day fasting and daily caloric restriction reverse the adverse effects of obesity, diabetes, and neuroinflammation on spatial learning and memory.

In a clinical trial, older adults on a short-term regimen of caloric restriction had improved verbal memory. In a study involving overweight adults with mild cognitive impairment, 12 months of caloric restriction led to improvements in verbal memory,
executive function, and global cognition. More recently, a large, multicenter, randomized clinical trial showed that 2 years of daily caloric restriction led to a significant improvement in working memory. There is certainly a need to undertake further studies of intermittent fasting and cognition in older people, particularly given the absence of any pharmacologic therapies that influence brain aging and progression of neurodegenerative diseases.

... section on studies of the effect of IF on certain chronic conditions. ...

Practical Considerations

Despite the evidence for the health benefits of intermittent fasting and its applicability to many diseases, there are impediments to the widespread adoption of these eating patterns in the community and by patients. First, a diet of three meals with snacks every day is so ingrained in our culture that a change in this eating pattern will rarely be contemplated by patients or doctors. The abundance of food and extensive marketing in developed nations are also major hurdles to be overcome.

Second, on switching to an intermittent-fasting regimen, many people will experience hunger, irritability, and a reduced ability to concentrate during periods of food restriction. However, these initial side effects usually disappear within 1 month, and patients should be advised of this fact.

Third, most physicians are not trained to prescribe specific intermittent-fasting interventions. Physicians can advise patients to gradually, over a period of several months, reduce the time window during which they consume food each day, with the goal of fasting for 16 to 18 hours a day. Alternatively, physicians can recommend the 5:2 intermittent-fasting diet, with 900 to 1000 calories consumed 1 day per week for the first month and then 2 days per week for the second month, followed by further reductions to 750 calories 2 days per week for the third month and, ultimately, 500 calories 2 days per week for the fourth month. A dietitian or nutritionist should be consulted to ensure that the nutritional needs of the patient are being met and to provide continued counseling and education. As with all lifestyle interventions, it is important that physicians provide adequate information, ongoing communication and support, and regular positive reinforcement.


Preclinical studies and clinical trials have shown that intermittent fasting has broad-spectrum benefits for many health conditions, such as obesity, diabetes mellitus, cardiovascular disease, cancers, and neurologic disorders. Animal models show that intermittent fasting improves health throughout the life span, whereas clinical studies have mainly involved relatively short-term interventions, over a period of months. It remains to be determined whether people can maintain intermittent fasting for years and potentially accrue the benefits seen in animal models. Furthermore, clinical studies have focused mainly on overweight young and middle-age adults, and we cannot generalize to other age groups the benefits and safety of intermittent fasting that have been observed in these studies.

Although we do not fully understand the specific mechanisms, the beneficial effects of intermittent fasting involve metabolic switching and cellular stress resistance. However, some people are unable or unwilling to adhere to an intermittent-fasting regimen. By further understanding the processes that link intermittent fasting with broad health benefits, we may be able to develop targeted pharmacologic therapies that mimic the effects of intermittent fasting without the need to substantially alter feeding habits.

Studies of the mechanisms of caloric restriction and intermittent fasting in animal models have led to the development and testing of pharmacologic interventions that mimic the health and disease-modifying benefits of intermittent fasting. Examples include agents that impose a mild metabolic challenge (2-deoxyglucose, metformin, and mitochondrial-uncoupling agents), bolster mitochondrial bioenergetics (ketone ester or nicotinamide riboside), or inhibit the mTOR pathway (sirolimus). However, the available data from animal models suggest that the safety and efficacy of such pharmacologic approaches are likely to be inferior to those of intermittent fasting.
The only large-ish (116 participant) random clinical trial I've seen on 16/8 intermittent fasting concluded:

Time-restricted eating did not confer weight loss or cardiometabolic benefits in this study.

Participants in the IF group lost 1.17% of their body weight in 12 weeks vs 0.75% weight loss for the control group - a positive difference, but one that failed to achieve statistical significance (there was more variation person to person within groups in this 116-person study).

50 of the fasters had DEXA scans before & after the study to monitor changes in body composition and researchers discovered that 65% of the ~2 lbs of lost body weight came from muscle vs ~25% muscle loss in typical diets.
that was quite an useless study. the term ad libitum means "as much or as often as necessary or desired".

no amount of fasting will be able to control unrestricted overeating. yes, the intermittent fasting eating window can be as long as 8 hours, but i rarely eat for 8 straight hours. i am lucky to have the time for even two full meals. if you pack in 3000-4000+ calories in 8 hours, good luck burning off that much stored fat in the next 16. there is more to intermittent fasting than merely watching the clock then shoveling in a massive quantity of food you "desire" at the allowed times.

no indication of the diet or meal timing followed by the CMT (consistant meal timing) group was given either. was that group abiding to the strict 3 meal diet? if you eat three meals with 5-6 hour spacing, the reduced calories (no snacking?) and nearly IF meal timing (12/12 to 14/10 range) should probably trigger some weight loss in obese individuals which likely added additional bias.
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as it seems you did, i almost missed the comments at the end of your cited article...

"A Study that was Poorly Done"
"No Objective Measure of Compliance and Differential Attrition"
"Time-restricted Eating Misunderstood in Study"
"Why even do such a study without controlling for what a subject eats?"
"Everyday American Diet is the Culprit"

every comment was negative... here is one complete.

An incomplete study
Shreya Ahana Ayyub, PhD | Max Planck Institute for Biophysical Chemistry

As the authors cite in their introduction, the ideal TRF model as used in mice, employed an isocaloric high fat diet. In the study performed here, there is no provision for measuring caloric intake, let alone matching caloric intake in the CMT and TRE groups. There is also no account of macronutrients consumed in either group. Since the authors go on to highlight the importance of adequate protein consumption while adhering to a TRE diet, the lack of data on macronutrients consumed is a major shortcoming. Differential uptake of ad libitum snacking is likely to occur in these two comparison groups, with the TRE group more likely to snack due to longer periods of abstaining from food. This is another example of why overall caloric tracking is important before drawing conclusions about the efficacy of TRE. The inclusion of participants of diverse ethnicities is a strength. However, the authors have neither discussed the distribution of races in the two groups, nor addressed how the over-representation of caucasians in the CMT group (64%) might affect the results. Normal range of BMI differs considerably by race and perhaps the effects of TRE do as well. The study does not explore this. The description of BMI, waist-to-hip ratio, waist circumference and fat mass do not include any acknowledgement of differences by sex. Based on the factors I have discussed, the authors cannot unequivocally state that TRE is not effective for weight loss.
I think a lot of diet arguments come down to splitting hairs. It reminds me a lot of the investment world where people argue until their red in the face about the *best* investments - to the point of making things so complicated that it causes some people to be discouraged and not invest at all. Investing (or dieting) using proven methods is what is important - worrying about which proven method is best is quite trivial in comparison.

the term ad libitum means "as much or as often as necessary or desired".

no amount of fasting will be able to control unrestricted overeating.
Agreed (and ad libitum feeding was the control in your rat studies posted above...)

But here is another random control trial with 100 participants, this one comparing alternate day calorie restricted intermittent fasting with comparable continuous caloric restriction: Daily Calorie Restriction vs Alternate Day Fasting for Weight Loss

* Of those that stayed with it, the IF group had slightly more, but not statistically significant, weight loss at 6 months (6% vs 5.3%)
* The IF group had a larger drop out rate (38% dropped out vs 29% for continuous restriction)
* No consistent differences were seen between the groups for blood pressure, heart rate, plasma lipids, glucose, or markers of insulin resistance.
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where to start with this one...

Firstly ... wow, i didn't even think that was a word... lol... 1) there is no doubt in anyone's mind that a calorie restrictive diet (aka "eat less, move more") works well for 6 months. i wonder where these people are now.

2) ADF sounds horribly difficult. if i give up intermittent fasting for even one day, the next day is always a little harder. these people were having to do that every other day. i may have done this 5-6 times in the past 2 years... mostly from having unexpected commitments to friends where passing on eating anything would be more difficult to explain than i usually care to try. i'm sure i've said this before, but it actually took me 2 - 3 weeks to start adhering to a 16/8 IF. oddly, from that point on, i could easily do a 20/4 day. in a multi-day fast (i may have done maybe 4-5 at this point... 3 days being the longest), the first day has always been the hardest. i don't know if i'd ever suggest ADF or 5:2 IF... habits are almost as easy to make as they are difficult to break.

3) with this study, even the non-alternate days... the days between alternate days? ... there is a larger than 100% caloric intake... demanded? sounds a lot like ad libitum ... :) that's one horrible diet where you are forced to eat more than you want. IF has significantly reduced my desire for a lot of food. i eat many ½ sandwiches. i also attribute my success from a few simple diet eliminations.

IF is a way to diet, not what is in your diet. this study seems to have missed that non-minor point.