Move over paleo, keto and Whole30--the latest diet trend on everyone’s lips is fasting. The many different types of fasting--water fasting, intermittent fasting, time-restricted fasting, fasting mimicking diet--as well as sensationalist stories about massive weight loss and cancer cures linked to it, make it hard to tell whether fasting is just the latest gimmick or a tried and true method for promoting health and weight loss. So let’s slow down and get all the facts on fasting.
Where it began...Fasting is an ancient healing tradition that has been practiced in almost all cultures and religions. Our ancestors evolved in a world where food was scarce at times and therefore developed mechanisms to function optimally both physically and cognitively in a fasted state. In our modern society, overconsumption is the norm, and fasting is not part of our lifestyle. We are overfed and undernourished and this often leads to metabolic morbidities and chronic disease. Bringing back the practice of fasting into our lives has been shown to have many health benefits.
What it is...Fasting is strictly defined as the willing abstinence of food and drink. The types of fasting commonly practiced involve at least water, with varying amounts of caloric intake and time in the fasted state. Intermittent fasting is an umbrella term for these types of fasts. The 5:2 diet consists of low calorie intake (usually about 500 calories) two times per week; on the other days a normal diet is consumed. Alternate day fasting (ADF) is low or no calorie intake every other day and a normal diet in between. There are 24 hour water fasts one to two times a week with normal intake on the other days, known as the Eat Stop Eat diet. Some find these types of fasting diets hard to manage because of the day to day change in eating plans. The 16/8 diet is a time restricted diet that consists of eating whatever you normally eat within an 8 hour window and fasting the other 16 hours. This is done on a daily basis. Many folks find this diet appealing because they don’t need to change what they eat and just need to stick to a timed schedule. The Fasting Mimicking Diet (FMD) is a calorie restricted diet with very specific foods for 5 days out of the month for a minimum of 3 months. As the name says, it mimics a complete fast, allowing just enough researched specific food in to trick the body into thinking it is fully fasting.
Why people do it...The benefits of fasting are numerous: weight loss, an improved cholesterol and fats profile, improved sugar control and insulin sensitivity, decreased blood pressure, and decreased inflammation, all of which decrease the risk of diabetes and cardiovascular disease. Recent animal studies have shown that fasting for 2 or more days at at time can be extremely beneficial in cancer. In humans, fasting for 13 or more hours per night demonstrated a significant decrease in breast cancer recurrence. The prolonged fasting seen with FMD also stimulates anti-aging pathways that promote cell regeneration and rejuvenation, allowing the cell and the tissue to function better. When one fasts for at least 24-48 hours the body switches from sugar burning mode to fat burning mode known as ketosis.
What to know...Fasting is not without risks and if you have any medical problems, especially chronic illness like diabetes, you should talk with your doctor before you start any type of fast. Low blood sugar and dehyrdration are potential issues and if you feel unwell during a fast you should stop.
Final verdict...Fasting is a great option for a metabolic reset. The research on fasting is booming and from what we see so far it seems like the power of fasting can rival many pharmaceutical drugs out there. Even better? Fasting is absolutely free.