6 Things to Know About Fasting Before You Try It, According to Nutritionists

The allure of not counting macros or calories coupled with the promise of weight loss and longevity has thrust intermittent fasting into the limelight. It's a trend that doesn't appear to be going anywhere anytime soon.

而潜在的健康益处的研究s and risks of this structured way of eating continues to unfold, some dietitians are heeding caution before jumping on theOne Meal a Day (OMAD),Alternate Day Fasting (ADF)orWarrior Dietbandwagon.

Here are six things dietitians want you to know before you give fasting a try:

大多数美国人正在吃由ently throughout the day. According to theCenters for Disease Control and Prevention(CDC), only 10 percent of us are getting enough fruits and vegetables and 95 percent are falling short on fiber. It's no wonder why there's cause for concern that so many want to shorten this "feeding window" to just six or eight hours — or every other day.

"Depending on how long you fast and what you eat when you are eating, fasting could lead to vitamin and mineral deficiencies in addition to an inadequate amount of macronutrients like protein, carbohydrates and fats," says Bonnie Taub-Dix, RDN and author ofRead It Before You Eat It - Taking You from Label to Table. "It's also likely that you won't meet your needs for fiber."

It's human nature to look forward to meal time and perhaps even overdo it a bit when you've gone for so long without eating.

"[When intermittent fasting], people are usually prone to eat very large meals during eating times, which can cause gastrointestinal (GI) stress leading to indigestion and bloating," says dietitianPatricia Bannan, RDN. "This is particularly concerning for people withirritable bowel syndrome(IBS), who already have a more sensitive gut."

While no one likes to feel stuffed or bloated after a meal, those with IBS are especially vulnerable. According to theInternational Foundation for Gastrointestinal Disorders, about one out of every 10 people have this condition.

You don't have to go to extremes to get results. You'll probably get better, lasting results if you don't.

Researchers in a July 2017 study published in theJournal of American Medical Association of Internal Medicinelooked at both intermittent fasters and those who just restricted calories and found that both groups lost similar amounts of weight, but the fasting group had a higher dropout rate.

By making smaller changes to our diets like monitoring our portions and incorporating more whole foods like whole grains, fruits, vegetables, legumes and lean proteins, we're making less room for the unhealthy stuff with added sugars and salt.

If you think missing your snack between lunch and dinner makes you hangry, try going 24 hours (or longer) without food. While not all types of fasting are this extreme, ADF allows you to eat unlimited amounts one day and then no food or caloric beverages the next.

"Besides the discomfort of a rumbling belly, fasting could bring uncomfortable side effects," says Taub-Dix. "Skipping meals could cause blood sugar levels to plummet making some people feel lightheaded, dizzy and weak. It can also lead to irritability and a lack of focus."

Proponents of fasting claim that hunger pangs subside over time and actually list mental clarity as a benefit of this way of eating, but these are definitely concerns worth considering.

Intermittent fastingcan do a number on our hormones. A March 2019 study published inNutrientsvalidates that excessive calorie restriction can lead a disturbance in women's menstrual cycles and a decrease in testosterone for men.

Additionally, animal studies (including this January 2013 research published inPLOS ONE)have found that intermittent fasting disrupts the reproductive cycle in females and lowers testosterone levels in males.

As with most diets, one size does not fit all and fasting it no different. Because this type of eating is so structured with set times of when to eat and when not to eat —ultimately forcing you to ignore your hunger cues — it is not appropriate for anyone with a history of an eating disorder.

There are also safety concerns with certain conditions. "People with diabetes or low blood sugar need glucose throughout the day and fasting for periods of time can have dangerous effects," adds Bannan.

According toHarvard Health, people onblood pressuremedication, or people with electrolyte imbalances should avoid fasting. Additionally, kids, pregnant women or women who are trying to conceive should refrain from this type of eating pattern.