Skipping meals or going longer without food, known as “intermittent fasting,” is gaining popularity but is it a trend that’s right for you?

And what is it, anyway?

Fasting, according to Marshfield Clinic Dietitian Chrisanne Urban, is abstaining from or reducing eating, drinking or both for a set time. Some fasts call for no food or liquid, may be less restrictive or intermittent. Intermittent fasting severely limits calories you take in on certain days of the week or specific hours during a day.

“Intermittent fasting goes way back,” Urban said. “A lot of fasting methods go back to religious or spiritual beliefs since certain religions required periods of fasting.

“It goes back even further, to hunters and gatherers. They had to find food, which was hard since it wasn’t readily available. It’s not difficult today to find food. That’s part of the problem.

“So, the goal with intermittent fasting is to decrease the appetite by changing the body’s metabolism by slowing it down. It’s a timed approach to eating and doesn’t specify foods to eat or avoid.”

Check with your provider

If you want to lose weight, you may like to know this method is used for weight loss, like low-carb or high-protein diets, but before you start check with your primary care provider, Urban said.

“Fasting is not suitable for everyone and not recommended for people with certain medical conditions like diabetes, high blood pressure, heart disease and for pregnant or breastfeeding women,” she said. “It’s also not suitable for kids or if you’re on certain medications, so these are compelling reasons to first talk to your primary care medical team.”

Different types of fasts

There are many different types of fasting. One is alternate day fasting, known as the 5:2 method or the Fast Diet. Five days of the week are normal eating days, while the other two consecutive days restrict calories to 500–600 per day.

Another is Eat Stop Eat. You fast once or twice a week on random days with the goal of no food for 24 hours at a time. You may eat until 7 p.m. one day then fast until 7 p.m. the following day, then eat regularly afterward.

Then there’s the Warrior Diet in which you avoid eating for 20 hours and then eat during a four-hour timeframe. Oh, and the Lean Gains fast and even more to choose from.

Urban’s conclusion to all this fasting?

“There are not many research studies proving effects of intermittent fasting,” she said. “They’re short studies with limited participants. One conclusion is an intermittent eating plan may work short term but there’s a high dropout rate.”

There’s also common sense to consider. If you follow a plan, you could have be a strong desire to overeat after fasting.

“Is it playing around with hunger hormones?” she asked. “There’s so much we don’t know about those hormones. Does it trigger something in the brain to overeat? There was a study in the Journal of the American Medical Association in 2017 with 100 overweight people assigned to one of three eating plans – a traditional diet plan restricting daily caloric intake by the same amount every day; fasting on alternate days; and do whatever you’re doing by following normal eating habits. The 12-month study showed two diet groups lost weight but fasters did not fare any better than traditional calorie counters.”

Not all these programs say you can eat whatever you want, she added.

“Words of wisdom still bear out. You still have to watch what you eat, hydrate and exercise and if you’re exercising you may not want to fast.”