I just finished working from 5 a.m. to 10 p.m. Yup, the ever glamorous lifestyle of a medical student. The last meal I ate consisted of 2-3 hardboiled eggs I scarfed down as I ran into the hospital; because, even at 5 a.m. I am considered late for a day of work. I’ve arrived home only to see an empty fridge and realize no restaurants are open. I need to eat. I’ve read every blog post, seen every interview, and even heard from doctors that I should be eating every 4-6 hours. I mean I cannot possibly miss this meal, right? Not necessarily. Skipping a meal or two may not be the worst thing for me. In fact, a growing body of evidence suggests that missing meals (fasting) may be to my benefit.
Intermittent Fasting (IF) represents a unique approach to nutrition. The approach intends to burn fat and produce muscle when combined with a proper exercise regimen. The name underscores basic principles of the program: fasting for intermittent periods of time.
Research suggests a wide number of benefits: potential protective benefits against various cancers, fat loss, muscle building, curbing hunger cravings, as well as increased insulin sensitivity (refer to other posts on diabetes and insulin resistance). This article aims to introduce readers to IF while providing some basic background on the principles of this model. Hopefully this read encourages our audience to research IF and explore the possibility of incorporating IF into one’s own daily routine.
The basic principle centers upon caloric restriction for extended stretches of time. The idea behind this is two fold:
1) It falls in line with ancestral diet principles and
2) Induces hormonal responses that promote fat burning, muscle building, and overall well being.
The majority of blog posts and literature surrounding IF introduce it to us in the context of paleo dieting. The average cave man did not always have a fridge full of food to satisfy his primal hunger. Instead he went through cycles of feast (eating) and famine (fasting).
Incorporating an approach that keeps the body in between a fasting and fed state is a natural extension of our ancestral diet. Excessive feasting serves as a major contributor to the variety of metabolic symptoms that plague society, today.
Furthermore, hormonal changes govern IF’s effectiveness. The key hormone discussed here is Growth Hormone, a natural hormone that regulates metabolism and is released by the body during the following phases: starvation, extreme/intense exercise, and rest. It is involved in muscle synthesis as well as lipolysis (fat breakdown). Proponents of IF outline that fasting states induce the release of extra growth hormone—thus helping to promote simultaneous fat burning and muscle growth.
In addition to the obvious benefits of muscle mass development and fat burning IF has a number of potential benefits.
These may or may not include:
1. Satiety (feeling nice and full). This may seem counterintuitive but studies show even alternate day fasting (see more below) may promote satiety.
2. Diabetes. Promising research shows that IF may be an effective alternative to calorie restriction and weight loss to prevent diabetes. More research is pending and the authors themselves conclude more research is needed to make definitive conclusions. However preliminary reviews of IF as a way to combat diabetes are promising.
3. Help combat eating disorders by tackling restrictive eating and body image issues.
4. Cardioprotective (hearty healthy) benefits. New research suggests IF may even protect the heart and lead to weight loss.
Models of IF
The basic idea of IF may be simple enough. However, for those who may seem intimidated by the challenge of fasting, don’t worry. A number of IF techniques exist to appeal to beginners and experienced fasters alike. Literature suggests most people may feel uneasy for the first 7-10 days. So, if you decide to partake in this new regimen do not be discouraged by mild irritability or uneasiness with the adjustment. Although the idea of fasting may be simple, readers often wonder what to eat during prescribed meal times. The theory of IF does not mean one can eat whatever they desire during his or her feast period.
Adherents still need to incorporate healthy eating habits (e.g. non-processed foods, loads of fresh veggies, and good hormone free/free range meat).
For instance, if I were to eat a meal or two during my feast window, it may consist of a huge spinach salad with grass-fed beef, avocado, and a healthy dressing. Or, I may decide to have some fresh fish with steamed veggies. The point is that the feast period does not mean one can instantly hit the closest drive thru window since there was a prolonged fasting period.
Below is a small list with brief descriptions of some of the more popular ways individuals may approach incorporating IF:
Alternate Day Fasting—One of the more popular methods. Proposed by Dr. Varady of the University of Illinois, the diet aims to offer patients a more inviting approach to fasting. Instead of incorporating a daily fast, the diet asks patients to fast every other day. Varady recommends 500 calories during one meal every other day. Her research, although young and ongoing, is quite promising. Patients who abided by this approach were a) more likely to continue this diet long term and b) actually restricted calorie intake on their regular/non-fasting days. Researchers theorize they restricted calories on non-fasting days since their bodies became adapted to the new approach.
12/12—A great approach for beginners. This simply suggests that patients have a 12 hour fasting window, and a 12 hour feasting window. A popular schedule may be to fast from 7pm to 7am.
18/6—A variation of the 12/12 model: here patients fast for 18 hours and feast for 6. One schedule maybe to eat only from 1 p.m.-7 p.m.
Occasionally missing a meal—Some people just listen to their bodies and skip a meal from time to time. Proponents of this model suggest not forcing a meal may help curb binge eating and be beneficial when periodically used.
Intermittent fasting represents a new way to approach caloric restriction. Although research concerning the metabolic benefits of this approach is promising, larger studies are needed to support clinical claims. Those interested in the diet should definitely research more about the topic. Combining this approach with a proper diet may offer individuals a way to achieve new body and metabolic goals.
So, at 10 p.m. at night I have two simple choices. I can go to bed and enjoy the potential benefits of my fast. Or, try to get a quick meal given the annals of conventional wisdom. As I mentioned earlier, it may not be a bad thing to skip this particular meal. Enjoying the perks of integrated fasts may make me a bit stronger, leaner, and hopefully a wiser medical student…though I guess the literature is still pending on that last wish.
Dr. Ron’s Clinical Insights on Intermittent Fasting
I am personally using and prescribing intermittent fasting for selected patients. However, many of my patients are coming in with significant micronutrient deficiencies and weight gain from under eating, overstressing and over exercising. Often these are women. I don’t initially recommend IF for these patients. I need to make sure these patients are well-nourished to replete these missing nutrients and we have to work on stress reduction and life balance which are top priorities. Eating more frequently may have to be initially implemented to replace key nutrients. Once we restore nutrient deficiencies and any hormonal and metabolic imbalances and patients start feeling better, they can then incorporate IF into their lifestyle plan. IF used in the right context can potentially increase lifespan and reduce inflammation. However, adding IF to a nutrient-deficient diet can make matters worse and I have seen inflammatory markers and body weight actually increase as a result.
For individuals who are eating a very high carbohydrate diet, adding IF may backfire since it can generate extreme hunger followed by compensatory binge eating. You need to first fix your eating habits, with a focus on adding healthy fats, proteins and more plants, which will act as a natural appetite suppressant. Once your body and metabolism are prepared, then IF can be used effectively. I have busy patients who generally skip breakfast already, thinking they are fasting, but then they overeat processed foods and excess carbohydrates later which worsens their weight and underlying health issues.
Finally, I highly recommend you fast with a purpose that goes beyond just weight loss and achieving ideal body composition. In most cultures fasting is a selfless act devoted to some higher spirit, rather than the somewhat egotistic pursuit of ideal body composition. Just reflect on the list of fasts undertaken by Mahatma Gandhi if you need inspiration to selflessly skip just a single meal. If the word “fasting” sounds too spartan, just call it “meal skipping.”
Try fasting for a departed relative, your favorite god, a specific life goal or higher purpose, etc. I personally have noticed that on IF days I can think more clearly, exercise longer and stronger, and meditate with greater focus. There are times I do use it for somewhat selfish purposes. For example, I use it strategically for important meetings and presentations as a cognitive performance enhancer. It beats caffeine or stimulants since its natural and you avoid the inevitable “crash” from stimulants. If I knew about it in my earlier life, I would have used it for school exams. Today’s students flood their systems with sugar and caffeine…just think sodas, frappuccinos and energy drinks, which are staple fuels for kids today.
Giving IF a higher purpose will make it more effortless, will allow us to practice selflessness which all of us can benefit from, and in the end, you will still enjoy the physical and mental benefits.
Ronesh Sinha, M.D. is a physician for the Palo Alto Medical Foundation who sees high risk South Asian patients, he blogs at southasianhealthsolution.org, and co-hosts a South Asian radio show on health.