Intermittent fasting (IF) is a term that means fasting for a set period of time. IF is growing in popularity among health and fitness professionals to aide themselves and their clients in losing weight, gaining muscle, or maintaining an overall healthy and fit physique. Intermittent fasting is a relatively new topic in research, and as a result there isn’t a whole bunch done on humans to back it up, plus the studies tend to lack in sample size, study duration, and methodological consistency. Also, a lot of it is on animals. However, existing research looks promising, findings in humans are consistent with animal research (Patterson et al.,2012) and there is a substantial amount of anecdotal evidence on IF (I have experienced positive effects in myself, and have observed this method working in a large number of people). Some people are hesitant to engage in IF, but it has shown to be safe and effective. Also, it has been around for quite a long time as different religions engage in fasting on the regular and I haven’t heard of any of them famishing, declining in health, or dying because of it.
There are several different ways to go about IF. In this blog post, I will be explaining a few popular protocols including Alternate Day Fasting (ADF), Eat Stop Eat, 16:8 protocol, and the Warrior Diet (which is also very close to Bert Herring’s Fast Five protocol).
Just so you have a background of a few types of IF, let me break down a few of the protocols.
- Alternate Day Fasting (ADF): Fast for 36 hours; Feed for 12 hours. You pretty much eat every other day.
- Fast for an entire day (or days); Once or twice a week.
- 16:8 protocol: Pretty self-explanatory. Fast for 16 hours of the day; Feed for 8 hours
- Warrior Diet: Fast for 20 hours; Feed for 4 hours
- The Fast-5 Diet: Fast for 20 hours; Feed for 5 hours (Pretty much the same as the Warrior Diet with exception of 1 hour)…Click here for the FREE Fast Five e-book
For sake of the rest of the article and research presentation, calorie restriction (CR) is a restriction of your daily calories. It is often used in IF research for comparison between cutting calories only and cutting calories + fasting.
RESEARCH
(If you don’t care about the science or articles, please skip to the next section)
Here are a few excerpts of research articles that present significant findings:
Varady, K. A. 2011. “Intermittent Versus Daily Calorie Restriction: Which Diet Regimen Is More Effective for Weight Loss?” International Association for the Study of Obesity 12(7): e593-e601.
- “Results reveal similar weight loss and fat mass loss with 3 to 12 weeks’ intermittent CR (4–8%, 11–16%, respectively) and daily CR (5–8%, 10–20%, respectively). In contrast, less fat-free mass was lost in response to intermittent CR versus daily CR. These findings suggest that these diets are equally as effective in decreasing body weight and fat mass, although intermittent CR may be more effective for the retention of lean mass. “ [My comments: So pretty much, IF resulted in preserving muscle mass better than CR alone]
Patterson, R. E., G. A. Laughlin, A. Z. LaCroix, and S. J. Hartman. 2012. “Intermittent Fasting and Human Metabolic Health.” Journal of the Academy of Nutrition and Dietetics 115(8): 1203-1212. doi: http://dx.doi.org/10.1016/j.jand.2015.02.018. Accessed August 30, 2015.
This review looked at a few different protocols:
- All studies in this review (alternate day fasting, modified fasting, time-restricted feeding “found a significant decrease in at least one glucoregulatory marker. One study examined lipid levels with mixed results: improvements in high-density lipoprotein (HDL) cholesterol and TG, but increased low-density lipoprotein (LDL) cholesterol. One of two studies found significant improvements in inflammatory markers. “
- Alternate Day Fasting: “Although limited, these data suggest that alternate-day fasting regimens can result in modest weight loss. These data also show some positive effects on metabolic parameters, although these studies enrolled normal-weight adults who were unlikely to show substantial improvements in metabolic risk factors. However, Heilbronn and colleagues6 noted that self-reported hunger on fasting days was considerable and did not decrease over time, suggesting that alternate-day fasting may not be a feasible public health intervention. [My comment: I had a different experience. Fasting got easier the longer I did it. I noticed a significant change in my hunger after about 45 days…The study they mention here by Heilbronn and colleagues (2005) only lasted 22 days]
- Modified Fasting: Defined as “Modified regimens allow for the consumption of 20% to 25% of energy needs on scheduled fasting days. This regimen is the basis for the popular 5:2 diet, which involves severe energy restriction for 2 nonconsecutive days a week and ad libitum eating the other 5 days”……
- “We identified eight trials of modified fasting in human beings. Study sample sizes ranged from 10 to 107 adults, all of whom were overweight or obese. The duration of these fasting interventions ranged from 8 weeks to 6 months. Of the eight studies, only one instituted weekly exercise goals. Overall, six of eight studies (75%) reported statistically significant weight loss, which ranged from 3.2% in comparison to a control group16 over a 12-week period to 8.0% in a one-arm trial over an 8- week period.13 Two of five studies found significant decreases in fasting insulin, but none found reductions in fasting glucose. Three of the eight studies found significant improvements in lipid levels. Two of five studies found significant improvements in inflammatory markers, including C-reactive protein, tumor necrosis factor-alpha (TNF-a), adiponectin, leptin, and brain-derived neurotrophic factor (BDNF). Half of these studies assessed some aspect of mood or other behavior-related side effects in response to the fasting regimen. In general, these studies reported that a small number (generally <15%) of participants reported negative side effects, such as feeling cold, irritable, low energy, or hungry. However, there were mean improvements in mood, including reductions in tension, anger, and fatigue, and increases in self- confidence and positive mood.” [My comment: This is pretty cool! Not only is IF great for weight loss and preserving muscle, but it also helps with inflammation and BDNF levels which have been shown to promote neurogenesis and stimulate positive moods… Another interesting finding of this study was that there were positive psychological and energy responses as well]
- Time-Restricted Feeding: Defined as “These protocols allow individuals to consume ad libitum energy intake within specific windows, which induces fasting periods on a routine basis. Studies of <3 meals per day are indirect examinations of prolonged daily or nightly fasting periods.” …[Similar to the protocols that involve a feeding window]
- “The authors concluded that in mice, time-restricted feeding was associated with reductions in body weight, total cholesterol, TG, glucose, insulin, interleukin 6, and TNF-a as well as improvements in insulin sensitivity. “ [My comments: Typically I’ve found increases in both HDL and LDL levels in the research…which is good for HDL/bad for LDL… but research is mixed as some studies have found improvements for LDL as well]
- “Another crossover study compared the effect of consuming one afternoon meal per day for 8 weeks and reported 4.1% weight loss in comparison to an isocaloric diet consumed as three meals per day. One meal per day was also associated with reductions in fasting glucose and improvements in LDL and HDL cholesterol levels. Whereas self-reported hunger was higher in the morning for those consuming one meal per day, this fasting regimen was considered acceptable because there were no meaningful changes in tension, depression, anger, vigor, fatigue, or confusion.
Anson, R. M., Guo, Z., de Cabo, R., Iyun, T., Rios, M., Hagepanos, A.. . Mattson, M. P. (2003). Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. Proceedings of the National Academy of Sciences of the United States of America, 100(10), 6216-6220. doi:10.1073/pnas.1035720100
- “intermittent fasting resulted in beneficial effects that met or exceeded those of caloric restriction including reduced serum glucose and insulin levels and increased resistance of neurons in the brain to excitotoxic stress. Intermittent fasting, therefore, has beneficial effects on glucose regulation and neuronal resistance to injury in these mice that are independent of caloric intake. “ [My comments: Not only is IF good for the physique but it also prevents cellular and neurodegenerative diseases]
The “Next Section” of the Blog Post
Those I mentioned are just a few different options for fasting. If you are interested in trying, it is probably best to start by skipping breakfast. This will get you used to going without food for a period of time. I would say the hardest part about fasting is the mental aspect of it. Often we get sucked into thinking about food so often and we succumb to psychological hunger rather than ACTUAL hunger. Do you remember the last time you were actually hungry? When the last time your stomach actually growled? Since I think it is more of a mental fight than anything, it helps to keep your mouth busy and drink a lot of calorie-free fluids. You are allowed to drink zero-calorie drinks during your fasting period which may include coffee, green tea, or water. For my first 40 days of fasting, I drank my first cup of coffee in the morning with a couple teaspoons of almond milk and 2 Stevias yielding about 15 calories for the entire morning. The rest of my coffee for the day was black. I used that as a transition to pure black Cowboy Coffee until my window opens, which I now find to be not so bad after all. The best thing about intermittent fasting: it is cost-effective. It is not necessary to go out and buy supplements for the program you want to use. You just figure out what works best for you, and do it.
The idea of IF is controversial since the tale as old as time says to “eat 6 small meals a day” …or even 8 for the best physique. In fact, the majority of personal trainers will probably tell you to eat 6 small meals a day because it “speeds up metabolism” or to simply restrict the number of calories you eat each day (Again, referred to as Calorie Restriction and CR in this article). However, most personal trainers don’t keep up on RECENT RESEARCH and don’t read tons of articles on what is working and what is not. I’m not saying that eating 6 small meals a day or restricting your calories doesn’t work. It has worked for a lot of people over the years. I will say that IF will not slow down your metabolism and that there are a number of additional health and wellness benefits. Some of these benefits include:
- Eating 1 or 2 larger meals a day and feeling completely satisfied is much better than eating 6 small meals a day and never feeling FULLY satisfied… and feeling like you are constantly starving. (You can only shove so much food into your mouth in a 5-hour window)
- IF may be more effective at retaining lean body mass (Varady, 2011).
- By engaging in IF, you become more sensitive and resistant to junk food. It makes you actually want to eat healthier.
- Significant improvements in metabolic risk factors, insulin sensitivity, HDL cholesterol and Thyroglobulin-(a gene that helps with thyroid regulation) reduced inflammatory markers (Patterson, 2012)
- IF has neuroprotective effects that CR does not have and enhances the ability of cells to fight disease (Anson et al., 2003)
- IF may be easier to adhere to than CR
- When eating several small meals throughout the day you are constantly thinking about food. With IF you eat for brief amounts of time and then forget about it the rest of the day.
Side note: People often ask if they should eat a little something before working out to prevent muscle loss if their window is later in the day and they work out before their eating window. In a perfect world, I would suggest to workout in the middle of your window. However, due to schedules and the ultimate barrier of time, I have been using pure BCAAs before my workouts early in the morning and after those workouts (PURE BCAAs...the only thing I mix it with is myo drops because BCAAs taste like shit…Whatever you mix it with MUST be Zero calories). I chose to do this since Martin Berkhin (an IF expert) recommended it to prevent loss of muscle while on IF. I still need to do some more research on BCAAs to be fully convinced whether or not you need them if you can’t workout in the middle of your window. But if you are super worried about losing muscle, it wouldn’t hurt.
Another side note: IF or at least the timing of IF might be questionable for you depending on the intensity of the sport you engage in, the job you have, etc. Use common sense, ask questions, do your research, and consult your physician if needed.
One final note… If you do intermittent fasting, you will likely be able to eat whatever you want in your window and still reap benefits at first. However, after a few weeks, I recommend keeping track of your calories and eating the correct amount of calories to meet your specific goals. OBVIOUSLY, if you eat cheeseburgers, ice cream, and pizza every day in your window, it is going to inhibit your results.
If you still aren’t convinced, here are a couple of other good resources on the topic:
- My physical therapist friend, Chad Reilly blogs about IF all the time: Check out his Diet and Nutrition blog here
- Also, Martin Berkhin (a professional on the topic) has blogged extensively about IF, his personal success story, and a lot of his clients’ success stories: Click here to check out his website
Famous people who do fast: Ronda Rousey, Hugh Jackman, Abraham Lincoln, Jesus, Moses, Plato
Plato Quote:
Feel free to comment/ ask questions as always!
#SOE
REFERENCES
Anson, R. M., Guo, Z., de Cabo, R., Iyun, T., Rios, M., Hagepanos, A.. . Mattson, M. P. (2003). Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. Proceedings of the National Academy of Sciences of the United States of America, 100(10),
Heilbronn, L. K., Smith, S. R., Martin, C. K., Anton, S. D., & Ravussin, E. (2005). Alternate-day fasting in nonobese subjects: Effects on body weight, body composition, and energy metabolism. The American Journal of Clinical Nutrition, 81(1), 69.
Patterson, R. E., G. A. Laughlin, A. Z. LaCroix, and S. J. Hartman. 2012. “Intermittent Fasting and Human Metabolic Health.” Journal of the Academy of Nutrition and Dietetics 115(8): 1203-1212. doi: http://dx.doi.org/10.1016/j.jand.2015.02.018. Accessed August 30, 2015.
Varady, K. A. 2011. “Intermittent Versus Daily Calorie Restriction: Which Diet Regimen Is More Effective for Weight Loss?” International Association for the Study of Obesity 12(7): e593-e601.
Photo credit: http://macrorevolution.com/wp-content/uploads/2015/01/IF1.jpg
Photo credit: http://www.ridingwiththewindowdown.com/wp-content/uploads/2014/12/Platofasting.jpg