A study in Utah, where the Church of Jesus Christ of Latter-Day Saints is based, found that people who skipped meals once a month were about 40 percent less likely to be diagnosed with clogged arteries than those who did not regularly fast.
People did not have to "get religion" to benefit: non-Mormons who regularly took breaks from food also were less likely to have clogged arteries, scientists found.
They concede that their study is far from proof that periodic fasting is good for anyone, but said the benefit they observed poses a theory that deserves further testing.
"It might suggest these are people who just control eating habits better," and that this discipline extends to other areas of their lives that improves their health, said Benjamin Horne, a heart disease researcher from Intermountain Medical Center and the University of Utah in Salt Lake City.
He led the study and reported results at a recent American Heart Association conference. The research was partly funded by the National Heart, Lung, and Blood Institute.
Roughly 70 percent of Utah residents are Mormons, whose religion advises abstaining from food on the first Sunday of each month, Horne said.
Researchers got the idea to study fasting after analyzing medical records of patients who had X-ray exams to check for blocked heart arteries between 1994 and 2002 in the Intermountain Health Collaborative Study, a health registry. Of these patients, 4,629 could be diagnosed as clearly having or lacking heart disease, an artery at least 70 percent clogged.
Researchers saw a typical pattern: only 61 percent of Mormons had heart disease compared to 66 percent of non-Mormons. They thought tobacco use probably accounted for the difference. But after taking smoking into account, they still saw a lower rate of heart disease among Mormons and designed a survey to explore why.
It asked about Mormons' religious practices: monthly fasting; avoiding tea, coffee and alcohol; taking a weekly day of rest; going to church, and donating time or money to charity.
Among the 515 people surveyed, only fasting made a significant difference in heart risks: 59 percent of periodic meal skippers were diagnosed with heart disease versus 67 percent of the others.
The difference persisted even when researchers took weight, age and conditions like diabetes or high cholesterol or blood pressure into account. About 8 percent of those surveyed were not Mormons, and those who regularly fasted had lower rates of heart disease, too.
Horne speculated that when people take a break from food, it forces the body to dip into fat reserves to burn calories. It also keeps the body from being constantly exposed to sugar and having to make insulin to metabolize it. When people develop diabetes, insulin-producing cells become less sensitive to cues from eating, so fasting may provide brief rests that resensitize these cells and make them work better, he said.
But he and other doctors cautioned that skipping meals is not advised for diabetics -- it could cause dangerous swings in blood sugar.
Also for dieters, "the news is not as good as you might think" on fasting, said Dr. Raymond Gibbons of the Mayo Clinic, a former heart association president.
"Fasting resets the metabolic rate," slowing it down to adjust to less food and forcing the body to store calories as soon as people resume eating, Gibbons said.