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05/19/2016 10:06 pm ET | Updated May 19, 2016

3 Biological Reasons Children Crave Carbs (And Why It's Not Such a Bad Thing)

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You serve dinner with all the food groups and your kids first reach for the pasta, bread, rice, tortillas or whatever carb source you have on the table. After a while, you remind them of the other food on their table or plate. Maybe you get so frustrated you simply instruct them to eat some protein or veggies.

Believe it or not, a child's preference for carbs is a key barrier to raising them to have a healthy relationship with food. Not because children enjoy carbs but because parents don't always understand the why behind their preferences, and may end up drawing the wrong conclusions.

Research reveals some interesting facts about why kids eat the way they do that every parent needs to know. These three facts in particular, can help you understand why most kids are naturally drawn to the starchy and sweet stuff.

1. Carbs Signal Safe Energy

The most common explanation for children preferring sweet over bitter is that it signals a safe source of energy. According to this review in the European Journal of Clinical Nutrition:

A sweet taste in nature indicates energy, which is needed for optimal growth and development. Therefore, it would seem safe for the young to consume foods with a sweet taste. Breast milk is also sweet, and this would confirm the link between a sweet taste and safe energy.

The preference for sweetness seems to change with age according to research. In one study, school age children (9-10 years), adolescents (14-16 years) and adults (20-25 years) were given a taste test with different sucrose concentrations. The school age children preferred the higher sweet concentrations than the adolescents but the adolescents preferred higher sweet intensities than the adults. This is consistent with other studies that show that sweet preferences decline when growth is complete.

2.Carbs are Brain Food

Researchers from Northwester University set out to determine the energy costs of the brain from birth to adulthood. Using MRI and PET data, they discovered that glucose uptake by the brain doesn't peak at birth as previously thought, but during the slow period of growth between toddlerhood and puberty. During this time the metabolic needs shift from growth of the body to metabolic needs of the brain. For example, at birth 35.4-38.7% of daily energy requirements go to brain-glucose uptake but this climbs to 43.3-43.8 during childhood.

The researchers believe that this period of delayed growth in childhood evolved so the unique human brain can fully develop, not so much in size but in key processes like synaptic growth. In order to do this, the brain relies heavily on glucose, which is why a child's brain uses twice as much glucose as an adults brain does. Brain glucose requirements peak at about five years of age (almost half of daily energy intake goes to the brain!), years before adult brain size is reached.

This adds additional evidence as to why preschoolers and young school-age children are drawn to starchy carbs like bread and crackers that readily provide glucose to the developing brain.

3. Carbs Play a Key Role in Growth

Children were given sweet drinks and then categorized into high sweet preference and low preference. These two groups did not differ in by age, body weight, stage of puberty, height or gender. Where they did differ is a measurement referred to NTx, a marker of bone growth that can be detected in urine. The results showed that the children that were still growing showed a heightened preference for sweets compared to those who had stopped growing (around 15-16).

The lead researcher of the study, Nancy Coldwell, was interviewed on NPR:

Exactly how this all works is still somewhat of a mystery, but Coldwell says that one important clue lies in the discovery that growing bones actually secrete hormones that can influence metabolism. Other well-known metabolic hormones like leptin and insulin have been shown to act on brain areas that control cravings and appetites, and even directly bind to the tongue, where they affect the preference for sweet tastes. Coldwell suspects that hormones from growing bones may be doing the same thing. In other words, it's not your kid's fault he raided the cookie jar - the hormones from his growing bones made him do it.

"I don't know for sure, but I am very suspicious that the bones are somehow telling either the brain or the tongue that there is energy needed for their growth and signaling for that preference to increase," says Coldwell.

This may explain why kids on low-carbohydrate ketogenic diets for seizures don't grow as well as children on regular diets even when calorie intakes are similar.

How This Information Helps

Understanding carbohydrates play an important role in growth can be helpful, and even a relief, for some parents. Instead of assuming a child is addicted to carbs, we can understand their natural biological drive to eat them.

What can you do? Aim for that middle ground. If you restrict too much, it can result in what researchers call eating in "the absence of hunger." And when these cravings naturally decrease with age, those that were restricted may keep eating because they can instead of listening to their body. But if you allow kids free reign with food choices, their diet will be imbalanced, often too high in sugar and refined carbs.

Instead, set the eating schedule and offer a good share of quality carbs like fruits, whole grains, dairy and beans while offering sweets in a reasonable manner. Vary the food from meal to meal, but don't interfere with the choices children make from what you offer (see Satter Division of Responsibility for more on this).

The real key is understanding why eating preferences look different for kids than it does for adults. This knowledge helps you stay consistent and prevents you from falling into the feeding traps that makes for a tense table, and negatively affects a child's relationships with food and enjoyment of eating.

This post originally appeared on Maryann's blog, Raise Healthy Eaters.

Having trouble cooking one meal for the whole family? My latest book, What to Cook for Dinner with Kids, shows you how.

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