North American wolf packs can feast on bison or elk and then go two weeks before the next kill. But the wolves’ bodies and brains still perform at high levels as they hunt for their next meal, researchers say.

Humans, too, appear well-adapted to periods of hunger. This is likely a trait evolved from early human hunter-gatherers who, like wolves, alternated between periods of feast and famine.

The answer as to how the body manages this, UF researchers said, provides insight into an increasingly popular dieting strategy —intermittent fasting.

UF Health researchers said in a recent study published in the journal Obesity that emerging findings in scientific literature show intermittent fasting can be a reliable means of weight loss and may optimize physiological functioning, enhance performance and slow the aging and disease process.

To understand why, one must look to how the body essentially flips a “metabolic switch” during fasting. This means the body moves from burning glucose, or sugar, for energy to fatty acids and their byproduct, ketones. During fasting, the body converts fat into fatty acids, which can be absorbed by the blood.

Stephen Anton, PhD, the division chief of clinical research for the UF College of Medicine’s department of aging and geriatric research and
the paper’s lead author, said research indicates ketones are the preferred fuel for the brain and body during periods of fasting and
extended exercise.

Ketones, he said, are a cleaner source of energy than glucose, protein or carbohydrates, the body’s other sources of energy. That is because ketones produce fewer “metabolic disrupters,” or molecules that can harm cells.

“This switch can happen after a certain period of time fasting,” said Anton, who also is affiliated with th eUF Institute on Aging. “It’s a gradation in which your metabolism over time shifts to use higher and higher amounts of ketones for energy.”

Typically, he said, after eight to 12 hours of fasting, the levels of ketones in the blood significantly increase.

This article originally appeared on UF Health News.