‘Intermittent fasting may have health benefits for some people’ Alaska Pulse; Vol. 1 No. 5 May, 2020

Fast, exercise, and limit sugar 

The Covid-19 pandemic and call for social distancing, isolation and quarantine presents a kind of hell to persons with addictions, eating disorders or other compulsive habits. Gyms are closed and deliberate attempts to exercise may be inconvenient or even dangerous. Comical social media memes warn of the dangers of weight gain for the isolated and bored. However, this is anything but funny. Most adults in this country are trending toward weight gain even while working daily jobs. During quarantine, eating may be a convenient hobby. 

Intermittent fasting is the practice of prolonged fasting. This can be either for 24 hour periods on occasion (3-4 days weekly) or engaging in daily fasts of upto 20 hours (time restricted feeding). The scientific basis for this is the understanding that having high levels of blood glucose increases the insulin output that leads to insulin resistance, weight gain, aging and diabetes. Benefits of caloric restriction have been observed in the past in both human and animal models, but it appears that prolonged fasting has additional benefits even when the same number of calories is consumed and when those calories come from foods high in fats or carbohydrates. Benefits of low carbohydrate diets have been demonstrated consistently as well (this includes sugar, grains, potatoes, corn and various other starches) in reduction of weight and risk for diabetes. 

Many people in this country will have prediabetes ( a hemoglobin A1C of 5.7% or an average blood glucose of 120+mg/dL) by their thirties or forties. The number of children with diabetes or prediabetes has also increased over the last decade. Signs that a person might be at risk for diabetes include being overweight, having thickened and hyperpigmented skin on the back of neck or under arms, and feeling ‘hypoglycemic’ or shaky/fatigued with even short fasts and at technically normal blood glucose levels. The more commonly noted and concerning signs of poorly controlled diabetes are increased thirst, hunger and need to urinate. 

The benefits of intermittent fasting go beyond reduction in risk for diabetes. They include weight loss and maintenance of a healthy body mass index, improved cardiovascular endurance, less fatigue during the day, possibly increased lifespan (but certainly healthspan). Fasting decreases general inflammation and increases clean up of damaged cells, shrinking some tumors and making them more susceptible to treatment. 

A fairly strict ketogenic diet does work for weight loss, but is difficult for most people to adhere to compared to simply not eating. The fasting for > 18 hours puts the body into ketosis and initiates the body using it’s fat stores for energy. If one does this every day and exercises most days, (especially if combined with a whole foods diet when one does eat), that individual should enjoy prolonged health at a normal body mass index. 

I started time restricted feeding (the daily fast for upto 20 hours daily) during my third pregnancy as my weight got away from me and I was experiencing nausea, vomiting, appetite loss and diarrhea. At first, my fasting was to limit my gastrointestinal symptoms. Gut rest reduced all of these symptoms. I had already gained (and mostly lost) about 50 lb each during the other pregnancies, more than that recommended in pregnancy. I had run for exercise off and on since I was a teen, but didn’t do much else that was active and didn’t watch what I ate (with the exception of a brief 1-2 weeks of the Adkins diet back when I was in college). Postpartum, I rapidly lost weight on the fast with breastfeeding. By the time my third child was a year old I weighed much less than my pre-pregnancy weight. I weighed less than my high school weight. At 5’,8.5” I had achieved a BMI around 20-21. It had previously been closer to 25-26, the borderline between normal and overweight. I couldn’t attribute this weight loss to breastfeeding alone. I had breastfed with my other children and hadn’t lost as much, by about 15-30 lb. I’ve now seen patients lose upto 30 lb in a month at the beginning of intermittent fasting. These patients will often have reduced hemoglobin A1C values after several months of the diet, indicating improved glycemic control. 

Another positive about the fasting is that my endurance has increased. Studies have reported that fasting can have this effect on people. I can run for well over an hour at greater than 6 MPH, 5/7 days of the week. I can do pull-ups. Never in my twenties did I ever believe I could do these things regularly. I have never been an athlete. It is hard to believe that I have become one in my late 30’s.

There are a few drawbacks I have noticed over three years of being on 18-20 hour daily fasts. I become extremely tired after eating; especially with large, carbohydrate-heavy meals. I do tend to binge during my allotted eating period- often on calorie dense foods (which is not what I tell my patients to do). It is difficult to tell if this is different from my prior natural state. Afterall, I started the diet out of a sense of lack of control of my eating in the first place.  I eat whatever is available when it is time to eat, which is part of why this is a convenient diet for me. I am convinced that if I binged less and ate only whole foods, I would maintain an even leaner body mass. Some of the pounds do come back, usually when my food choices are less healthful, but BMI is still around 21. 

There are some relative contraindications to intermittent fasting. People with certain medical problems should be monitored by a physician before initiating this diet. People on medications that lead to hypoglycemia (like insulin) should consult with their physician prior to starting the diet. People who are underweight should not fast for prolonged periods. This diet is not appropriate for babies or young children. It may not be appropriate for those with certain mental health disorders, known eating disorders or nutritional deficiencies. People who have had bariatric surgical procedures or any gastrointestinal resections should consult with their physician before initiating this diet. 

Caloric restriction and fasting have been demonstrated to prolong life and decrease mortality in several animal models. But there is another secret to staying healthy and decreasing all-cause mortality. That is exercise. Aerobic exercise and improved cardiovascular endurance are associated with a decrease in all-cause mortality. Studies on men doing push-ups have also associated ability to perform more push-ups with decrease in all cause mortality. Those that perform better on treadmill stress tests, are less likely to die from cardiovascular causes. Performing regular aerobics limits spikes in blood glucose by improving utilization of glucose even at rest. This decreases insulin resistance and risk for diabetes. While even a little exercise is helpful, there seems to be no upper limit to the amount of aerobic exercise that one can get and still benefit the cardiovascular system. Exercise to one’s aerobic tolerance limit should, therefore, be encouraged. Intermittent fasting can help people reach their fitness goals.  

Being stuck at home and out of work can lead to unhealthy habits. Hopefully, this article has encouraged people to initiate healthy ones. Specifically: limit carbohydrates (especially processed) in diet and eat whole foods. If there are no medical contraindications, try intermittent fasting. Get at least thirty minutes of aerobics most days and remember there is no upper limit.