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- NEW YORK - People
who don't eat anything until around dinner time, but who can't stop eating
until almost morning, may have a new eating disorder that is quite unlike
either anorexia or bulimia nervosa, investigators suggest.
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- A report on "night-eating syndrome" is published
in Wednesday's issue of The Journal of the American Medical Association.
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- Dr. Grethe Stea Birketvedt from the University of Pennsylvania
School of Medicine in Philadelphia, and colleagues from there and from
the University Hospital of Tromso, Norway, compared behavior in 10 obese
subjects whose eating behavior was characterized by lack of appetite in
the morning, followed by a large consumption of calories during the evening
and at night, with that of 10, similarly obese control subjects who were
not night eaters.
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- Although the amount of food consumed by the two groups
was only "modestly" different, "the pattern of daytime and
nighttime food intake of the two groups differed dramatically," the
researchers point out. For example, night eaters recorded 9.3 eating episodes
during the 24-hour study period compared with 4.2 eating episodes recorded
by controls.
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- Between 8 p.m. and 6 a.m., "night eaters consumed
56% of their (daily) energy intake compared with 15% consumed by the control
subjects," investigators add. On average, night eaters also woke up
far more often during the night than did controls, and on approximately
half of these awakenings, night eaters would consume roughly 250 calories
in the form of a snack " 70% of which was in the form of carbohydrates.
In comparison, none of the controls ate during their nighttime awakenings,
the team points out.
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- In a related study, Norwegian investigators compared
hormonal patterns between 12 night eaters and 11 overweight subjects who
did not eat at night, again over a 24-hour period. Seven out of the 12
night eaters in the Norwegian study were not obese.
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- "As in the behavioral study,... nighttime awakenings
were far more common among the night eaters... than among the controls,"
the Norwegian investigators observe.
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- Compared with controls, the group also found that blood
levels of the hormones melatonin and leptin did not go up to the same extent
as they did in controls. Melatonin is thought to help people fall and stay
asleep, while leptin is believed to suppress appetite.
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- Between 8 a.m. and 2 a.m., levels of cortisol, another
hormone, were also higher in night eaters than in controls.
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- "Contrary to the usual pattern found in depression,
the mood of the night eaters (also) fell during the evening," the
group adds.
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- Birketvedt told Reuters Health that night eaters are
quite distinct from people with the eating disorder bulimia nervosa, who
may eat huge amounts at one sitting but who do not snack all the time.
In contrast, night eaters, "eat little until dinner time, after which
they can't stop eating almost until the morning," she said.
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- When night eaters wake up in the middle of the night,
"they also wake up wanting to eat, not particularly because they are
hungry but because they have this urge to eat," Birketvedt added.
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- Birketvedt estimated that up to 1.5% of the adult population
in many countries including the United States have this pattern of disordered
night eating. Because so many people are affected by the syndrome, "these
findings are important," she felt.
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- In an accompanying editorial, Dr. Joel Yager from the
University of New Mexico School of Medicine in Albuquerque, suggested that
more study is required "before the exact importance of these findings
is known."
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- He also expressed reservations about whether supplemental
melatonin or leptin suggested by investigators as potential treatments
for night eaters "will prove clinically useful."
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