'Right' Time vs. 'Wrong' Time continued...
The only variable, she says, was when the food was consumed.
Arble can't say for sure why the mice that ate at the ''wrong'' time gained so much more weight. ''We speculate that it's the interplay between body temperature, metabolic hormones such as leptin, and the sleep-wake cycle," she says.
For humans, nighttime is a time for rest, as the body temperature declines, she says. "Eating at night is contradicting your body's natural circadian rhythm,'' she says. "The leptin levels are starting to rise, and are supposed to be discouraging you from eating." Rising leptin levels suppress appetite.
She is hopeful that other researchers will focus on the same concept in human studies. "If it turns out to be a major factor,'' she says of the food timing, ''it will be a great way to help weight maintenance and maybe weight loss. It would be a fairly simple behavior modification, to move the time you are eating."
But night-time eating would be one factor among many contributing to weight gain, Arble tells WebMD. "I don't want people to read this study and think 'Oh, I can eat as much as I want as long as it's the right time of day.'"
''Eating too much late at night is not good," says Arline D. Salbe, PhD, a senior research fellow at the Kronos Longevity Research Institute in Phoenix, who has also researched and published on the topic.
''In a simple but elegant study design using mice, Arble [and her colleagues] have confirmed our own results in humans that nighttime eating is a risk for weight gain," says Salbe. "As modern lifestyles continue to modify work and sleep patterns, the risk of weight gain from nighttime energy intake becomes more relevant to greater numbers of people," she tells WebMD.
In her own study, Salbe and her colleagues evaluated the food intake of 94 people over a three-day period while they stayed in a clinical research unit and were allowed to eat as much as they wished. They found that 29 were night eaters, defined as those who ate between 11 p.m. and 5 a.m. on at least one of the three days; 65 were not night eaters.