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Restrictive diets often are prescribed for preventing and managing disease. But new evidence suggests that periodically shunning food and drink altogether is good for your health.
A pair of studies by cardiologists at Intermountain Medical Center found that fasting lowers one's risk of coronary artery disease and diabetes. Skipping meals also caused changes in cholesterol levels and reduced other cardiac risk factors such as blood sugar levels, weight and triglycerides, the chemical form of fat, the studies show.
The discovery is a cultural curiosity in Utah where many members of The Church of Jesus Christ of Latter-day Saints fast for one day each month. It may also have clinical applications.
It's not time to start a fasting diet just yet. More research is needed to understand the body's short- and long-term responses, said the lead researcher, Benjamin D. Horne, director of cardiovascular and genetic epidemiology at Intermountain Medical Center in Murray.
But Horne believes taking regular breaks from food could one day prove to be useful medicine.
He will present his findings Sunday at an annual meeting of the American College of Cardiology in New Orleans. The research piggybacks on another Intermountain Healthcare study in 2007 that found people who skip meals once a month are about 40 percent less likely to be diagnosed with clogged arteries than those who don't.
This year, to "verify that what we found was more than a statistical anomaly," Horne said his team surveyed another 200 people, patients and healthy volunteers. Among those who said they routinely abstain from food and drink for extended periods of time, 63 percent had heart disease, as diagnosed by X-rays showing clogged arteries. By comparison, 75 percent of those who didn't fast had plaque-filled arteries.
Fasting was also linked to lower rates of diabetes.
To rule out the possibility that people who fast simply live cleaner lives and benefit from other good habits, Intermountain researchers then studied the effects of fasting on the human body. In a clinical trial, they asked 30 people who had no history of fasting to go without food for 24 hours. Participants ingested nothing but water "not even gum," said Horne.
Blood tests and other measurements run before and during the fast showed dramatic swings in certain biomarkers for heart disease.
Fasting drove participants' total cholesterol levels up: low-density lipoprotein cholesterol (the "bad" cholesterol) and high-density lipoprotein cholesterol (the "good" cholesterol) rose 14 percent and 6 percent, respectively.
A form of stress, fasting causes the body to release more cholesterol, allowing it to switch from glucose to fat as a source of fuel.
This decreases the number of fat cells in the body, which is important "because the fewer fat cells a body has, the less likely it will experience insulin resistance, or diabetes," Horne explained. "It's generally thought this [switch] happens after three days of fasting, but these data suggest it happens earlier, within the first 24 hours."
Fasting also triggered an increase in human growth hormone, a protein that in adults helps regulate metabolism and preserve lean muscle, said Horne. Hormone levels increased an average of 1,300 percent in women and nearly 2,000 percent in men.
Also not surprisingly, participants' triglycerides and blood sugar levels dropped and there was some weight loss.
Maureen Newman, an occupational health nurse from Sandy who has been volunteering for the American Heart Association for 25 years, said it's "gratifying" to know studies are being done on how to prevent heart disease, a leading killer of men and women worldwide.
But she cautions that fasting can have downsides, especially for people with chronic health problems such as diabetes and kidney disease. And fasting for long periods to lose weight can backfire by lowering your metabolism, Newman said. "Anytime you're doing something different with your diet, you want to clear that with a physician."
How much fasting is recommended, for how long and for whom are issues Horne hopes to further explore. Most immediately, the Intermountain team plans to screen for more metabolic factors in blood samples stored from its recent trial. Also in the works is a human trial with coronary artery-disease patients.
About the IHC research
Intermountain Medical Center cardiologists tested fasting on the human body and found it reduces risk factors for coronary artery disease.
Researchers got the idea after analyzing medical records of patients who had angiograms between 1994 and 2002 in the Intermountain Health Collaborative Study, a health registry. They noticed Mormons were less likely to have heart disease than non-Mormons and, after accounting for the effects of tobacco use, designed studies to explore why.