From Personal Use to Clinical Practice: Dr. Jonathan Chung talks Intermittent Fasting
Jonathan Chung is a chiropractor specializing in head, neck and spine, and also an avid athlete and CrossFitter. When a fellow CrossFit athlete suggested he try intermittent fasting to enhance his workout performance, he was intrigued.
“Being athletically active, I am always tinkering and trying to figure out how to eat to best maintain my lean body mass but also to perform at a high level during my workouts,” Dr. Chung said. “A friend told me that since he had started intermittent fasting, he had been recovering from workouts more quickly with less soreness. He also said he felt really good, cognitively and physically, while fasting.”
Curious, Chung looked to the scientific literature, where he found a litany of animal studies and some human studies claiming health benefits of intermittent fasting.
“I didn’t know how well animal studies could predict benefits of intermittent fasting in humans, but it seemed harmless to experiment with moderate fasting intervals,” Chung said.
Chung was intrigued by the 16:8 fasting routine. He started fasting 16 hours per day, typically from around 8pm to noon, and eating only during an 8-hour window. He immediately found that intermittent fasting was far easier and more effective for him, in terms of dieting, than trying to count his calories or obsess about what he was eating. He only struggled with hunger pains in the very beginning, as well as following breaks from his fasting routine during vacation, for example.
“I’m not much of a breakfast person anyway,” Chung said. “I started eating my last meal around 8pm, and not eating again until around 12:30pm the next day. After the first few days of this, I found that I wasn’t that much hungrier by noon without breakfast than with breakfast. I started off fasting a few days per week, and now I typically fast five days per week, 16 hours per day.”
Chung also started thinking about food and hunger differently.
“Whenever I feel hungry, I mentally tell myself it’s just my body’s physiology adapting to the fasting routine,” Chung said. “I would tell myself, ‘This hunger is a good thing right now, embrace it.’ It’s like embracing and appreciating a difficult workout.”
There’s an adjustment period to intermittent fasting, Chung says — an athlete whose body is accustomed to “carbing up” might have a very rough time trying to switch to a different metabolic state before a big race. “The first time I went into ketosis from fasting, my workouts suffered tremendously,” Chung said. “I would tank during an aerobic workout during the first few weeks of adjusting to intermittent fasting.” Try experimenting with fasting in your off-season, Chung recommends, when your body has time to adjust to burning fats for energy before competitions begin.
For athletes attempting intermittent fasting, Chung recommends, based on work by nutritional biochemistry and physiology researcher Bill Lagakos, skipping dinner and eating breakfast in the morning to coincide with light and a normal circadian rhythm. This might also help athletes who train in the mornings or early afternoons, Chung says, in terms of energy levels. “But it depends on your schedule and what works for you,” Chung said.
Chung was eager to evaluate how intermittent fasting would affect his own body mass and fitness. He says that while he didn’t notice any substantial improvements in his conditioning level, after a period of adaptation, he certainly didn’t notice any downsides. However, he experienced meaningful improvement in his heart-rate variability, and he found that while in a fasted state in the mornings, he felt sharper cognitively.
Several studies have revealed that intermittent fasting has beneficial effects on cardiovascular and cerebrovascular systems, including reduced blood pressure, improved stress adaptation and heart rate variability, effects that are similar to those of physical exercise. Preserved heart rate variability is associated with longevity. Clinical studies have also found fasting to be associated with increased alertness, mood improvement in people with chronic pain syndromes, and increased brain availability of serotonin and other molecules that have pain-relieving effects.
Chung has stuck with intermittent fasting, as part of his lifestyle. He has also begun to incorporate fasting into his chiropractic practice. At Keystone Chiropractic in Royal Palm Beach, Florida, Dr. Chung specializes in treating the head, neck, spine and nervous system. He treats and corrects Atlas Displacement Complex and chronic issues including migraine headaches, vertigo and balance problems, jaw pain, spinal stenosis, fibromyalgia, and movement disorders. He also regularly sees patients suffering from concussions and brain injury.
“I started to see evidence in the literature of intermittent fasting have benefits for patients with mild cognitive impairment and Alzheimer’s disease, and even some scientific work on the benefits of caloric restriction for cancer patients,” Chung said. “I realized that there was a whole lot more to intermittent fasting than weight control. The cognitive benefits of fasting made a lot of sense to me, because I had started to notice more mental clarity myself while in a fasted state.”
Since he started fasting himself, Chung has experimented with a ketogenic diet in addition to fasting, which he found further enhanced his feelings of cognitive sharpness or clarity. He started recommending intermittent fasting and a ketogenic diet to some of his patients suffering from mild cognitive impairment, Alzheimer’s disease and migraines. Some of his patients have responded extremely well to these interventions.
“That got me really excited about using intermittent fasting therapeutically, in my practice,” Dr. Chung said. “If any of my patients hit plateaus during chiropractic treatment and therapy, we start thinking outside of the box on what else we can try that is safe and easy to implement. At this stage, I’ve started to recommend to these patients that they attempt a 4–8 week period of intermittent fasting or ketogenic diet. I’ve seen some of my headache patients respond very well to this intervention. Some of my patients suffering mild cognitive impairment due to Parkinson’s disease feel a bit sharper and less forgetful while fasting or eating keto.”
There is science to back this up, too. Beneficial neurological effects of fasting and ketogenic diets are linked to decreased glucose availability in the brain and accompanying responses inside of our brain cells to handle this “good stress.” Neurons, or brain cells, respond to a decrease in glucose availability and a rise in ketone body availability (produced as our bodies burn fat instead of carbohydrates for fuel) by activating signaling pathways that promote neuronal survival and plasticity, production of BDNF (brain-derived neurotrophic factor) and even potentially neurogenesis, the production of new neurons. However, scientists are still unclear on whether substantial neurogenesis can occur in human adults.
When our brain cells have to use ketones versus glucose for energy, they tend to ramp up the production of new mitochondria and produce fewer reactive oxygen species that can cause DNA damage, for example. The end result is that fasting, caloric restriction and a ketogenic diet may reduce neuro-inflammation, improve memory, increase insulin sensitivity, protect brain cells from damage for example after a stroke, replace lost or dysfunctional neurons and improve function in the aging brain, as well as activate pain-relieving chemicals. On the other hand, a diet rich in refined sugars and saturated fats can reduce BDNF levels in the hippocampus and impair spatial memory. Fasting also has a long history in the treatment of epilepsy.
“My patients often improve in terms of body composition, body weight and metabolic issues, and cognition is something that I see improve consistently, when people stick to the intervention,” Chung said. “Getting people to stick to an intermittent fasting routine, however, is often challenging, especially when I’m telling people to try a new ‘diet’ before the winter holidays.”
Most of Chung’s patients who try intermittent fasting based on his recommendation and stick with it for four to eight weeks, he says, typically experience beneficial effects, or no effects at all. He says he is aware, however, of evidence that some women react negatively to being in ketosis, and advises that patients discontinue fasting if they feel any worse.
In 2011 randomized trial in young overweight women, a small number of women undergoing intermittent restricted diet interventions complained of hunger, lack and energy, headache or feeling cold. However, most women did not experience major adverse effects, and typically experienced positive effects in terms of an increase in serum total ketone bodies, weight loss, increased insulin sensitivity and decreased inflammatory marker protein concentrations.
Dr. Chung admits that he while doesn’t fully understand the cellular mechanisms underlying the neurological symptom-related benefits of fasting, he suspects a reduction in neuro-inflammation plays a role. But he’s been doing more research as he sees intermittent fasting work for more patients. And of course, he’s experimenting on himself first, so that he can speak from experience with his patients on some of the challenges involved and what to expect while fasting.
“The things I see in my office, along with early studies among Parkinson’s patients, has me pretty excited about intermittent fasting,” Chung said. “I also think patients feel more connected to their doctor if they feel that their doctor has been through the challenges that they are going through, so it’s important that I’m able to talk to my patients about intermittent fasting from experience.”
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