People choose to fast for a variety of reasons, whether they are related to health, weight loss, finances or religion. Fasting can range from juice-only fasts to fasts that exclude all food and fluid, such as dry fasting. While fasts could occasionally have some health benefits, they could also be very dangerous. Fasting has negative impacts in the short and long term, and has detrimental effects for many people, including those who want to lose weight. Ultimately, the effects of abstaining from food vary largely based on the individual who is fasting.
Fasting can actually be detrimental for weight management, according to registered dietitians on MayoClinic.com. After a period of fasting, research shows people tend to crave starchier foods, with higher calorie content. Carbohydrates are the body’s preferred source of fuel. Extreme hunger also causes you to pack on more calories than are healthy for the body to consume in one sitting. Ultimately, fasting can reverse the intended effects of a weight management plan.
Short-Term Side Effects
There are many short-term side effects of fasting. These include headaches, dizziness, lightheadedness, fatigue, low blood pressure and abnormal heart rhythms. People who are fasting may experience an impaired ability to conduct certain tasks, such as operate machinery or drive a vehicle. Fasting could also cause flareups of certain conditions such as gout or gallstones. Fasting could impair the body’s ability to absorb certain medications or even alter drug interactions in the body.
Long-Term Side Effects
Fasting has detrimental impacts in the long term as well. Not only can fasting damage the immune system, it can also negatively affect many of the body’s organs, including the liver and kidneys. Fasting could interfere with vital bodily function. Abstaining from eating could also be potentially dangerous in individuals who are already malnourished, for example, cancer patients. It’s even possible for fasting to result in death when the body’s stored energy is entirely depleted.
While there are many methods of fasting, dry fasting — or avoiding all fluid and food intake — is particularly dangerous. Dry fasting can quickly lead to dehydration and death in just a matter of days. The American Cancer Society reports the health impact of dry fasting varies largely based on the individual and context. Factors such as heat, heavy exertion and compromised health can make dry fasting lethal in just a matter of hours.