Do you head to the refrigerator before bedtime for a late-night snack? Snacking is a big part of American culture. In fact, many people are eating smaller, snack-sized meals rather than a few larger ones. Eating a few healthy snacks during the day helps to curb hunger, but late night snacking and snacking at bedtime may not be good for your health or your waistline. Here’s why.
Does Snacking at Night Lead to Weight Gain?
According to the USDA Department of Agriculture’s Weight Information website, weight control is about how much you eat, what you eat, and how much physical activity you get, not when you consume your calories. On the surface that makes sense, but a number of studies show that eating later in the evening has metabolic effects that influence weight control. Insulin sensitivity, a marker for metabolic health, is typically higher earlier in the day and declines later in the day. When insulin sensitivity goes down in the evening, it’s easier for your body to store fat.
A study involving 420 healthy participants in Spain who were trying to lose weight suggests meal timing DOES influence weight loss. In this study, participants who ate their primary meal of the day before 3:00 P.M. lost more weight than those who ate their main meal later, despite the fact they ate the same number of calories and engaged in similar amounts of physical activity.
Why is the Desire to Have a Bedtime Snack So Common?
Did you know some people consume half of their daily calories at dinner and afterward? What drives people to nosh so late at night? According to a study published in the journal Obesity, the desire for late night snacks may be a vestige of early ancestral times when food was scarce and consuming calories when food was available equated with survival. This study suggests our human biological clock and circadian rhythms drive us to nibble at night.
Despite its possible survival advantages, the drive to snack at night may be counterproductive since your body is best primed to burn fat when you’re active during the day. After dinner, your body goes into “rest and relax” mode where it winds down to prepare for sleep. That’s when insulin sensitivity drops and your body can more easily store fat. Hormones that control hunger, fat storage, and glucose metabolism are regulated by circadian rhythms controlled by an internal biological clock that lies in a portion of the brain called the hypothalamus. This part of your brain, called the suprachiasmatic nucleus, is like the director of the hormonal orchestra. The suprachiasmatic nucleus is closely tuned to environmental signals, for example, whether it’s light outside or dark. In response to these signals, it turns genes on and off that produce hormones that control appetite.
Does science support this idea? A study carried out at Oregon Health and Science University showed hunger tends to peak at around 8:00 P.M, whereas most people are least hungry when they first get up in the morning. In a sense, biological clock and circadian rhythms work against us by making us hungry when our bodies are least capable of handling nutrients from a metabolic standpoint.
A recent study carried out in rodents showed mice that ate a high-fat diet only during a restricted time period each day, between 9 and 12 hours, gained less weight than mice given access to food at all hours, even when though they ate a similar number of calories. Even when the mice were allowed to “splurge” by eating high-fat meals two days a week (similar to a cheat weekend), the mice that ate within a restricted time period during the week gained less weight than their counterparts. Eating at all hours of the day and evening, at least in mice, isn’t conducive to weight control.
Many people these days lead lives similar to the mice in the study. They eat at all hours of the day and night and stay up long after the sun goes down. At one time, human biological clocks were “set” by light and dark cycles. These days, biological clocks are no longer set to sunrise and sunset. Instead, we expose our eyes to artificial light and computer screens, sometimes into the wee hours of the night, thereby disrupting our natural biological rhythms. Some experts believe this partially explains the rise in metabolic disorders like insulin resistance. Modern-day brains still haven’t adapted to being out of sync with the natural environment.
Other Problems with Snacking at Night
Research shows late-night snackers often don’t make healthy food choices. The late-night snack menu is more likely to include foods high in fat and carbs. Plus, distracted and mindless eating is the new norm with many people munching in front of a computer screen or while watching television.
How Can You Tame the Late-Night Snacking Beast?
Keep a food journal and monitor how much you’re eating and the composition of your diet. If you’re skipping meals and restricting calories during the day, you’re going to feel ravenous at night. Skipping breakfast is a no-no. Some studies show breakfast skippers consume more calories later in the day.
Make sure you’re getting enough dietary protein and fiber-rich foods to keep you feeling full and satisfied. Hold off on processed carbs, foods and beverages with added sugar and carbs that are low in fiber. These foods take your blood sugar on a roller coaster ride that can trigger cravings.
Lastly, trade that late-night snack time for more sleep. Skimping on sleep has been linked with weight gain and metabolic problems in a number of studies.
If you do need a snack before bedtime, make it high in protein. There’s a big difference between having a brownie before bedtime and a protein-rich bowl of cottage cheese. If you’re hungry in the evening, choose your snack wisely.
The Bottom Line?
Make healthy snacks a part of your diet, but don’t let late-night snacking become a habit. Instead, focus on winding down after dinner and making time for sleep.
Women’s Health. “How to Cut Out Late Night Snacking” December 31, 2013.
WebMD. “Diet Truth or Myth: Eating at Night Causes Weight Gain”
Oregon Health and Science University. “Study explains what triggers those late-night snack cravings”
The Scientist Magazine. “Out of Sync” (September 2013)
Science Daily. “Another Case Against the Midnight Snack: Researchers Tinker with a Time-Restricted Diet in Mice and Find It’s Remarkably Forgiving”
Harvard School of Public Health. “Sleep Deprivation and Obesity”
Obesity (Silver Spring). 2008 Mar;16(3):643-53. doi: 10.1038/oby.2007.118. Epub 2008 Jan 17.
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