Have you ever noticed a sudden change in your mood and appetite when late afternoon rolls around? Many people have experienced a predictable and routine change in their mood and energy level between around 3:30 to 5:00 pm. But just what causes this strange phenomenon that makes us seek out carbohydrate-rich foods? More importantly, should we give into these cravings for carbohydrates or find ways to distract ourselves to avoid reaching into the cabinets or rummaging through the fridge for a quick carb fix?

Believe it or not, there is a scientific explanation behind your diminished mood and energy level. Blame this lack of control over your eating habits on the combination of the time of day and changes in the level of serotonin (the feel-good hormone) in your brain. Serotonin is a chemical produced in the brain that stabilizes your mood and regulates your appetite. Signs that your serotonin level has decreased include irritability, impatience, fatigue, inability to concentrate, anger, and a depressed mood. Naturally, our bodies send signals for us to consume carbohydrates during this dip in serotonin because carbohydrates increase your brain's production of serotonin. This series of biochemical reactions in your brain is similar to the mood-boosting effect of antidepressants.

Late afternoon hankerings for sweet or starchy foods may be worse for those who are dieting or limiting their carbohydrate intake. People on high-protein, low-carbohydrate diets tend to have stronger cravings for carbohydrates than people whose diets are comprised of the recommended percentages of macronutrients (carbohydrate, fat, and protein). People stuck on the low-carb diet craze tend to experience intense cravings for starchy foods because they've deprived their bodies of this much-needed nutrient. In fact, carbohydrates should be the most abundant macronutrient in your diet and are the preferred fuel of your brain and nervous system.

The key to keeping your serotonin level (and your waistline) in check is to eat nutrient-rich foods at the right times and in proper portions. If your craving for carbohydrates in the late afternoon doesn't cause you to go on an out-of-control eating binge, have a small snack containing about 30 grams of carbohydrate. Your brain will provide a much-needed surge in serotonin in approximately 20-30 minutes after ingesting a carbohydrate-rich snack. However, there is no need to down an entire carton of ice cream to remedy your decreased energy and diminished mood because your body doesn't require a large amount of carbohydrates to cause an increased production of the feel-good chemical serotonin.

Like all healthy, portion-controlled snacks, aim for something with fewer than 200 calories. A medium apple, a handful of pretzels or low-fat crackers, or a snack-sized bag of microwaveable popcorn will do the trick. Carbohydrate-rich snacks do not have consist of high calorie, high fat, nutrient-poor choices. Aim for starches that are low in fat (fat slows the production of serotonin) and nutrient-dense. Where people get into trouble with satisfying their afternoon carb cravings is when they eat out of boredom, stress, or temptation, and choose high calorie foods such as potato chips, cookies, pastries, chocolate, or ice cream. Enjoy healthy carbohydrates in proper portions.