What Jackman was experiencing, Dubost said, was symptomatic of dehydration - which, if ignored, can carry ramifications such as brain damage, seizure, and, in extreme cases, death.
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"This isn't something that should be taken lightly," Dubost said. "Unfortunately, a lot of people look at what celebrities do and think they can take it on as well, but that's really not the case."
While Dubost sees no benefits in complete fasts, others think that a milder form of fasting could help certain populations. Intermittent fasting, proponents say, produces a milder stress on the body similar to exercise.
"Exercise is an energetic stress, where you have a marked increase in energy expenditure," said Mark Mattson, chief of the laboratory of neurosciences at the National Institute on Aging. An approach like intermittent fasting may work in a similar way, he says, "by putting an energetic stress on the body, but in kind of the opposite way, through reduced energy availability."