In recent years, intermittent fasting has been widely adopted by fitness gurus and health experts alike, citing increased energy levels, improved metabolic health and a reduced risk of cardiovascular disease as a few potential benefits. With the concern surrounding COVID-19, there’s also a growing interest in its immune-boosting effects.
However, it’s important to note that there are also possible health implications associated with such a restrictive eating pattern.
“While fasting can bolster your immune system, you need to make sure you have sufficient micro and macro nutrients to keep your whole body strong,” says Dr. Chris Meletis, N.D. “Vitamins, minerals and calories are all essential for your immune system to function properly.”
In summary, intermittent fasting is seen as a way of cleansing the body of toxins and boosting your immunity by allocating dedicated windows for meal times and fasting in between. Depending on the type of fasting method you choose, this could be anything from the classic 16/8 format – where meals are restricted to an 8-hour window – to a weekly, 24-hour fast.
Meletis says the patients that seem to benefit the most from intermittent fasting are those suffering from prediabetes or metabolic system, as well as those with the goal of losing excess weight.
“Some people just have an unhealthy relationship with food and the sense of structure that comes from intermittent fasting really helps them,” he says.
It’s important to note, however, that intermittent fasting isn’t for everyone. Genetics, ancestry and medical history all play a role in the effect a fasting diet may have on a person's health.
“If you suffer from hypoglycemia, intermittent fasting can present some very real risks,” Meletis says. In addition to the usual signs of low blood sugar – such as fatigue, shakiness and an irregular heartbeat – hypoglycemia can lead to more serious symptoms, including blurred vision, seizures and loss of consciousness.
In general, intermittent fasting is also not recommended for individuals with a history of eating disorders. It’s also important to take mental health and mood disorders into consideration, Meletis says, given that our gut and brain are closely connected.
"Fasting can be stressful,” he says. “You’re robbing the brain and body of glucose, which can cause a spike in cortisol — your body’s primary stress hormone.”
Because our bodies and hormones are so complex, the effects of intermittent fasting can also greatly vary from person to person. For example, thyroid hormones generally drop during fasting, which can cause a spike in reverse T3 (rT3), slowing down your metabolism and making it harder to lose weight. Conversely, Meletis says, those who are already at a low body weight may be at risk of becoming underweight through fasting.
“Not everyone can healthily fast for 16 hours and still achieve their health goals,” he says. “For this reason, a personalized approach is key.”
Even when using intermittent fasting a weight loss tool, Meletis says, it’s crucial to make sure you’re consuming enough protein and nutrient-rich foods throughout the day. Trying to pack all the same foods and portion sizes into a smaller window of time is both counterproductive and unsustainable, he says.
Before deciding to experiment with intermittent fasting, it's important to talk to your primary care physician, as certain medications can cause a drop in blood sugar. It’s also a good idea to get some baseline tests done to measure your electrolytes, blood sugar and cortisol levels.
“In a world where ‘more’ is considered ‘better,’ many people push their bodies too fast for too long,” he says. “When it comes to intermittent fasting, listening to your body is crucial.”