Intermittent Fasting | Part II
A majority of the scientific literature supports the notion that longevity is associated with fasting. “Fasting,” “Intermittent Fasting,” or “Fasting Mimicking Diets” are patterns of eating that essentially give the body (1) a period of rest and (2) a chance to use an anti-inflammatory fuel source known as ketones (small fragments of fat easily used for energy). As counterintuitive as it may sound, time without food is vital to our health and wellbeing. Below are a couple of example of different types of fasts:
Partial day fasting. Intermittently skipping 1 to 2 meals per day, which results in 0 calorie consumed for around 14 to 16 hrs at night (ie., skipping breakfast) to 24 hrs (i.e., skipping breakfast and dinner ) on alternating days. This form of fasting is practiced by many and extremely common in many Eastern traditions for centuries. For most people who begin partial day fasting, they usually start with 12 to 14 hours at night and work their way up. As practiced during the Muslim month of Ramadan, absolutely no food is consumed during daylight (i.e., no breakfast or lunch).
Single day fasting. No food is consumed from the evening of day no. 1 to the morning of day no. 3, which is roughly 36 hours.
Multiple day fasting. No food is consumed for 48 hours or longer.
5:2 intermittent fasting. A more targeted and flexible maintenance plan, food is restricted to 500-600 kcal per day for 2 days per week, and they can be either consecutive or separated by one or more days of unrestricted eating.
As I explained last year in Intermittent Fasting to Reduce Autoimmunity, I recommend everyone give their body a period of rest from digesting food. The biggest reason is actively digesting food is an incredibly taxing process, requiring a lot of energy. To our genes, it’s the “norm” to have a break every now and then, yet in our go-go-go culture, there’s no rest for the gut. In today’s post, I want to explain why in certain situations we use caution with the various approaches to weight loss and metabolic health.
For starters, if one is beginning a fast, it’s very important to get a sense of what type of fast is best suited for you. Understanding the language of the “fasting world”, and associated health goals, is key. Everyone has to be on the same page, patient and practitioner.
For example, any fasting regimen that exceeds 24 hours has not been shown effective in sustaining weight loss long term. So, if someone is interested in losing weight, 24+ fasts are probably not the best option. Yes, these single day fasts can temporarily enhance initial weight loss, but they too often come with a hefty price tag. Just one day of fasting results in the loss of body protein from lean tissue. While this sounds innocuous, lean tissue loss occurs in all vital organs, including the muscle, heart, liver, and kidneys. These vital organs, while they have the capacity to function without sustained periods of food, need to be preserved, and they can be with well developed fasting plans. Unfortunately, the excitement of a significant amount of weight loss in the beginning for 24+ hour fasts comes with the high cost of shedding metabolically active tissue. This is not sustainable long term.
Hence, the distinction between nutritional ketosis and fasting and/or starving ketosis. When fasting is implemented correctly, nutritional ketosis (i.e. the body using fats as the main source of fuel) is achieved while concomitantly maintaining lean tissue protein and function. On the other hand, fasting/starving ketosis reduces the body’s resting metabolism, strength, and bodily functions. Both processes force the body to run on ketones, small fatty acids, but only nutritional ketosis maintains maximal metabolism, strength, and function.
While humans are equipped to and have evolved to survive disease or famine by fasting for weeks to months at a time, to say this rationale is the basis for frequent multiple days fasts may not be truly justified. For every fasting 24-hour period after the first day, the human body needs around 2-3 days of optimum food intake to recover what was lost to keep the body alive. This means that an individual could do a total 24-hour fast 2 days per week and still be able to catch up on what was lost in between, but the concern then becomes (1) overeating during those “catch up” days and (2) recovering lean tissue and metabolic rate is not a guarantee. Evolutionarily speaking, this makes sense, as our ancestors likely experienced true famine events a few times in their lives and learned to survive fairly effectively. And so, doing intermittent fasting every week of every month can be a game changer for supporting cellular health and vitality.
Please note that if a person is taking pharmaceutical drugs for chronic diseases such as diabetes, heart disease, high blood pressure, and anticoagulation, they may require medication adjustments when engaging in intermittent fasting. The reason is as the body uses up easily stored glucose, it will then switch to using ketones as the main fuel source and allow blood insulin requirements to drastically drop. Also making sure to remove the major food culprits associated with causing diabetes, high blood pressure and diabetes (i.e., animal protein, processed sugar, genetically modified corn, soy, wheat, and rice, alcohol) during a fast is critical for improving total body function.
Yet, these medications will need to be promptly resumed upon re-introduction of the standard American diet (i.e., meats, fish, dairy products, whole grains, alcohol, coffee). Otherwise, a person will be at significant risk of major fluctuations in blood sugar levels and blood pressure. It is critical to work with an integrative and functional medicine practitioner who specializes in the in’s and out’s of intermittent fasting and how best to address the underlying root causes of diabetes, heart disease, and high blood pressure so that fasting isn’t so dangerous.
Lastly, for almost a century, we’ve observed that people who were rescued from starvation (i.e., a famine, lifeboat, or concentration camp) are actually at risk of sudden death if they abruptly eat lots of food. Refeeding syndrome is the official medical name. Therefore, controlled refeeding with healthcare guidance is the solution to prevent sudden death. Note, most people are well-nourished before they begin fasting, so it takes at least a week or two of fasting before refeeding syndrome poses any real risk. However, previous dieting and/or fasting, aging, and chronic illness(s) can truncate this interval before the risk for sudden death begins.
In summary, whether or not fasting becomes counterproductive depends on many factors. If someone has diabetes and is taking insulin, limiting or eliminating animal protein, GMO whole grains, caffeine, and refined sugar/processed dried food for a mere day will significantly change their disease (in a great way) and their medication dosing needed for that day. Fasting and resuming eating both directly alter how an individual responds to common medications; i.e. adding back dietary sugar sets off the blood glucose roller-coaster. Conversely, if one is disease-free but has a physically or mentally demanding job, one will likely “hit the wall” on day no. 2 of fasting, resulting in a decrease in physical and mental performance. Additionally, many people in my practice have marginal levels of many essential minerals (i.e., potassium, magnesium) and vitamins (i.e., B12, folate, D) whose levels will suddenly drop when they begin intermittent fasting. It is because is using up these resources aggressively to address many cellular functions during the fasting period. These levels will naturally jump back to sustainable levels once the body is able to balance itself.
So, the question remains: How do we make up for the losses of those bodily proteins and minerals which continue or accelerate leaving the body on the days we don’t eat?
The answer comes back to the ketogenic diet. We know that a well-formulated ketogenic plant-based diet sustains (if not significantly improves) a person’s health and function, both during weight loss and also in weight maintenance. Again, one of the key attributes to consuming a well-formulated ketogenic diet every day is that it preserves lean tissue and essential minerals without generating deficits. No “catch up” eating days are required and “nutritional ketosis” is in full swing. With a simple ketone measurement, we can tell if the well formulated ketogenic plant-based diet is implemented correctly.
Fasting is a time-honored tradition in many cultures and we respect everyone’s journey and decision to fast. Of course, one can lose weight more rapidly with total fasting, but the sustainability of this option is wanting. So, if weight loss is your goal, striving to be in a state of nutritional ketosis may be the best option long term.
AUTHOR
Dr. Payal Bhandari M.D. is one of U.S.'s top leading integrative functional medical physicians and the founder of SF Advanced Health. She combines the best in Eastern and Western Medicine to understand the root causes of diseases and provide patients with personalized treatment plans that quickly deliver effective results. Dr. Bhandari specializes in cell function to understand how the whole body works. Dr. Bhandari received her Bachelor of Arts degree in biology in 1997 and Doctor of Medicine degree in 2001 from West Virginia University. She the completed her Family Medicine residency in 2004 from the University of Massachusetts and joined a family medicine practice in 2005 which was eventually nationally recognized as San Francisco’s 1st patient-centered medical home. To learn more, go to www.sfadvancedhealth.com.