A controversial weight-loss debate is whether you are more likely to gain weight when you eat at night. Both sides have their own explanations, but the science behind it is complicated and difficult to test. Is it a myth that you gain weight when you eat at night, or is it a myth that it does not matter?
Sleeping
During the night, metabolism significantly slows, but the body is still working. The heart is beating, the blood is circulating, the lungs are functioning and the brain is active. Unless you wake up and have a snack, the food that you ate from the previous evening or night must be enough to satisfy you for eight to 10 hours. It can be said that your body undergoes an "overnight fast."
Controversy
Many experts, such as ones at Columbia University, claim that the body processes calories the same no matter the time: 2,000 calories is 2,000 calories regardless of when they are eaten, and "late night binges" are the more pernicious threat. Others claim that calories are more likely to be stored as fat during sedentary periods of repose during the night when the body isn't using as much energy. Bodybuilder Tom Venuto states that your body is more likely to release insulin at night and store energy as fat when other energy stores are full.
Study
A study conducted by researchers at Northwestern University and published in the journal Obesity tested bedtime eating conditions on mice. Although they were fed identical diets and performed similar amounts of exercise, the mice that had eaten during normal sleeping hours gained more weight than mice on a normal eating schedule. There are two important caveats, however. Both groups of mice were fed diets that contained 60 percent fat, an abnormally high amount, and gained weight; the control mice gained 20 percent weight, and the mice who ate during the night gained 48 percent. They did not test a normal diet. Second, human studies will still need to be conducted because each animal is different. For example, mice are nocturnal, so the study had to be done during the day.
Considerations
Fred Turek, director of the Center for Sleep and Circadian Biology at Northwestern University and the senior author of the study, states that humans evolved to forage between sunrise and sunset. They could not store their food or hunt easily during the night. It is also a period associated with low activity. Many late-night shift workers are known to have a higher risk for obesity, diabetes and other health problems. However, not all researchers agree. Another study by the Oregon National Primate Research Center was conducted on rhesus monkeys, which are a common model for studying primates. It found no changes in monkeys who ate at night. But this was an observation of the monkeys and not a rigorous study, so it is difficult to interpret the results.
Recommendation
The average human eats 24 to 65 percent of daily calories at night. This is probably more than at any point in history. Research has been contradictory, so be cautious. Eat a moderately sized meal with a restrained carbohydrate intake at least two hours before you go to bed.
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