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“Intermittent fasting” is a trend that has existed in the various health-conscious corners of the internet for a while now. Is fasting safe? Do fasting diets work?

Intermittent fasting (IF) is more like an eating schedule than an actual diet. While doing IF, people only eat within a relatively narrow range of hours during the day.

There are several styles of intermittent fasting. The primary and most popular way to do IF is the 16:8 style. This style pairs 16 hours of fasting with 8 hours of eating. For example, you would stop eating at 8 p.m. and wait to eat again until noon the next day. While fasting, you may consume only water, coffee, and tea.

So, is it safe to fast from food? Most people who try intermittent fasting only intend to restrict their eating hours but often reduce their caloric intake as a result. Calorie restriction isn’t the point of IF, though it tends to be a side effect. Rather, the point of IF is for the body to switch from burning glycogen to burning fat stored during the fasting period.

Those who do IF should focus on eating higher-quality foods, avoiding junk food and processed carbohydrates. Large quantities of carbs may undermine your progress. Instead, eat more fresh fruits and vegetables.

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Do Fasting Diets Work?

Intermittent fasting may be more effective than a traditional diet for weight loss, according to a study published in the Journal of Translational Medicine. The research found that people who did IF saw a significant decrease in fat mass over a period of eight weeks.

Another study published in the American Journal of Clinical Nutrition showed that those who did IF reduced their body weight and body fat percentage over an eight-week period. They were also able to decrease LDL cholesterol, triglycerides, and blood pressure.

Another study conducted on mice, from the National Academy of Sciences of the United States of America, concluded that IF may help increase insulin sensitivity. Further, a study in the journal Neurobiology of Disease indicated that intermittent fasting improved age-related memory function in mice.

Is Fasting Safe?

So, IF may aid weight loss, but is it safe to fast from food for 16 hours?

The truth is intermittent fasting safely and effectively boosts weight loss and improves blood sugar. Unlike many fad diets, IF is backed by plenty of medical literature. IF is generally safe and effective because it combines short periods of fasting with short periods of eating. Extending the fasting beyond a day to several consecutive days can become unsafe because it can put undue stress on the heart.

However, intermittent fasting can also be risky for certain people. Those who have low blood pressure, low blood sugar, or other potentially risky health problems should consult their doctor first.

People who are taking insulin or other medications that affect the blood sugar may struggle with IF because they need to eat more regularly to prevent blood sugar drops.

Anyone who has an eating disorder or a history of eating disorders should avoid intermittent fasting. IF may too closely resemble the cycle of bingeing and purging and trigger a relapse.

If you are on medication that must be taken with food in the morning or before bed, IF may not be the best choice, but there are ways to make it work. Anyone who is pregnant or plans to get pregnant should focus on eating healthfully instead of on weight loss. Remember to check with your doctor first, if you are unsure.

To make an appointment with one of our registered dietitians, call UPMC Nutrition Services at 1-800-533-8762.

About UPMC

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