You’ve pulled your shorts and swimsuit from the back of your closet and you’re feeling ready for summer—until you put them on, and remember those winter months you spent hiding out on the couch. Now, you’re looking for a quick fix to get in warm-weather shape, and set your calorie count in your sights. But cutting out meals is a no-no, right?
Not necessarily. Fasting is often thought of as an extreme measure that can upset your metabolism and eventually lead you to regain whatever weight you lose. But, according to some recent research, fasting may have unexpected health benefits.
Early research results
Several studies over the last few years have shown that intermittent fasting—skipping targeted meals, or avoiding eating a few days per week—may help lower cholesterol and even drop your risk for heart disease and cancer. Experts disagree whether fasting is a useful tool for weight loss, but some say calculated calorie restriction is key to success on the scale.
Dr. Luigi Fontana is a research professor at Washington University in St. Louis, and has studied the effects of fasting on both animals and humans. In animals, he says, it’s clear that cutting calories through fasting has a big impact. “Animals live up to 50% longer, and they’re much healthier,” he says. “Cancer and cardiovascular disease are prevented by these calorie restrictions, without malnutrition.” He says researchers aren’t sure exactly what triggers the health benefits, but he says it’s clear the human participants lost weight. Whether people will get the same long-term health benefits as animals, he says, remains to be seen.
Lose some, gain some
Though experts still aren’t sure whether fasting can help the heart and lower cholesterol, they do know it can help prevent diabetes. According to a study from Intermountain Medical Center in Murray, Utah, people who fasted for 24 hours at a time lost fat cells, which is key to lowering the risk of diabetes.
Dr. Krista Varady is a professor of nutrition at the University of Illinois at Chicago, and author of The Every-Other-Day Diet. In multiple fasting studies, she’s had participants try two approaches—fasting one day and eating normally the next, and alternating days of normal eating with days of a 500-calorie diet. She says her results have been clear: With both methods, people lost weight and fat cells, and ultimately lowered their diabetes risk. And surprisingly, they didn’t overeat when they could. “Usually, they only ate about 10% more on ‘feast’ day,” she says. Varady says her tests have primarily involved obese people, who are able to lose weight faster than people who weigh less. The results are significant, but not instant. Typically, obese people lost about two pounds per week, while smaller people might lose a half-pound per week.
Life in the too-fast lane
Still, fasting is not for everyone. Varady says it’s not a good idea for children or pregnant women. And not everyone is sold on the benefits of fasting. Julia Zumpano, a registered dietitian at the Cleveland Clinic, says she doesn’t think anyone should fast, unless it’s for religious purposes. People who try to lose weight this way often struggle to get results, she says, because they think they can treat themselves to a bigger portion later. Zumpano says our bodies typically function best when they can stick to a regular schedule. “Metabolically, it’s much better to eat more often, so you can keep your body burning,” she says. “When you lack nutrition for long periods of time, you’re more likely to overeat at that next meal and more likely to store calories.”