Adolescents and the Impact of a Low-Carbohydrate Nutrition Plan

Most research investigating adolescents and diet/nutrition is centered on starting the day off with a hearty breakfast (Carroll, 2014), with the goal of promoting mental and physical growth and development. But maybe more research needs to be done on what exactly a hearty breakfast entails and what children are eating the rest of the day. According to the Centers for Disease Control and Prevention, the obesity epidemic in the United States continues to rise. The National Health and Nutrition Examination Survey determined that 17% of children are obese (Ogden et al., 2015). This means that an alarming 17% of adolescents have a body mass index at or above the 95th percentile for their gender and age (National Collaborative on Childhood Obesity Research).

Obesity places these children (and adults) at an increased risk for asthma, sleep apnea, orthopedic problems, high blood pressure, type 2 diabetes and altered glucose metabolism (National Collaborative on Childhood Obesity Research). Therefore, while it is important to begin the day with a big, nutrient-dense meal, perhaps it is equally important to understand what happens throughout the day after breakfast is consumed. Most people are aware of the link between poor nutrition and increased risk for diseases; however, nutrition status and eating patterns also impact academic performance, sleep, and behavior (Carroll, 2014; Wilder Research, 2014). Considering that diet is a modifiable variable, unlike the genetics that we are born with, we should examine how diet influences our life on a daily basis.

Adolescents, Low-Carb Diets, and Academic Performance

Research investigating the impact of nutrition on academic performance in children has been limited to primarily studying: a) breakfast alone rather than nutrition over the course of the day, or b) eating “healthy” non-processed foods rather than emphasizing low-carb diets in children.

Information on low-carbohydrate nutrition plans in children is limited. Here is what we know. Carbohydrates are converted into glucose for our brain and body to use as fuel (Ross, 2010). Research has shown that the quality of carbohydrates consumed does matter. Consuming low-glycemic-index carbohydrates rather than high-glycemic-index carbohydrates has been linked to improved cognitive functioning, specifically in the domains of memory and attention (Carroll, 2014). The glycemic index is a measure of the quality of a carbohydrate based on how the food affects blood glucose levels and insulin. Low-glycemic-index carbohydrates are more slowly digested, resulting in a consistent, slow increase in blood glucose or energy, rather than spikes and crashes (Glycemic Index Foundation, 2013). This slow rise in blood glucose levels prevents us from experiencing negative side effects such as dizziness, confusion and altered cognitive functioning (Ross, 2010).

In a study where approximately 350,000 participants between 12 and 18 years of age were enrolled, researchers concluded that consistency in three daily meals and frequency of non-processed foods (e.g. fruits, vegetables, milk) were associated with better academic performance. Alternatively, consuming processed foods (e.g. soft drinks, fast foods, sugar-based foods) more frequently (≥7 times/week) was associated with poor academic performance (Kim et al., 2016). Researchers theorize that consumption of fruits and vegetables results in increased antioxidant levels, resulting in improved cognitive functioning (Kim et al., 2016).

Another study investigated how the quality of an adolescent’s diet (i.e. quantity of saturated fat, fiber, sugar) affected academic performance. The diets of approximately 700 participants were categorized into three groups: unhealthy, fair, and healthy. This study similarly concluded that academic performance (i.e. higher scores in math, language, and GPA) improved when consuming a diet comprised of higher quality foods (Correa-Burrows et al., 2016).

While studies have not investigated how a high-carbohydrate versus a low-carbohydrate diet impacts academic performance in children, those who consume larger quantities of non-processed foods versus processed foods were more likely to have lower levels of carbohydrate intake per day. Processed foods are not only loaded with an abundance of sugar (i.e. simple carbohydrates that fail to keep us full), they also have little to no nutritional value. This means they provide minimal amounts of vitamins and antioxidants when compared to non-processed foods. By minimizing processed foods, children are better able to avoid glucose spikes and post-sugar crashes. These crashes can result in the brain shutting down after sugar consumption, leading to decreased academic performance and shorter attention spans.

Adolescents, Low-Carb Diets, and Sleep

Researchers have hypothesized that nutrition (macronutrient composition and timing of meals) impacts sleep quality and duration. More specifically, manipulating carbohydrates is believed to play a role in sleep quality (St-Onge et al., 2016). While a low-carbohydrate diet and its impact on sleep in adolescents has not been heavily studied, one study found that adult participants who consumed a high-fat low-carb diet (65% fat, 25% carbs, 10% protein) experienced significantly better sleep as measured on the Pittsburgh Sleep Quality Index when compared to participants who consumed a high-carbohydrate, high-protein, or mixed macronutrient diet (Lindseth & Murray, 2016). Long-chain polyunsaturated fatty acids are believed to improve sleep quality and duration. These fatty acids are said to play a role in increasing both serotonin and melatonin levels (Lindseth & Murray, 2016). In another study, participants who consumed a low-carb diet experienced increased slow wave sleep as well as improved sleep efficiency, which is defined as “the amount of time in bed spent sleeping” (St-Onge et al., 2016).

Adolescents, Low-Carb Diets, and Behavior

Nutrition is believed to play a role in the behavior of children. In fact, diet has been heavily studied as a way to manage symptoms of Attention Deficit Hyperactivity Disorder (ADHD) (e.g. inattention, hyperactivity, and impulsivity), and has been used as either a complement to or an alternative to pharmacological management. While controversial, careful attention should be paid to food additives, refined sugars, and food allergies/insensitivities to improve the symptoms of children who experience hyperactivity and behavioral problems (Schnoll et al., 2003). In a study of 88 children ages 6-13 years, researchers identified a correlation between increased sleep disturbance in children diagnosed with ADHD and the consumption of high-carbohydrate diets. These researchers found high amounts of refined sugars to be the biggest indicator of sleep disturbance, hyperactivity and impulsivity (Blunden et al., 2011).


While the relationship between diet and behavior in children is still a widely debated topic, many health professionals recommend managing spikes in blood sugar with the rationale that blood sugar spikes and crashes result in behavioral issues, including an inability to listen, decreased attention and focus, increased irritability, increased anger, and increased restlessness (Luther, 2016). A drop in blood glucose levels initiates a cascade where the body releases adrenaline, resulting in increased cortisol (i.e. the “stress” hormone) levels. During this process, the brain is affected by the changes in glucose levels (Luther, 2016). Reducing carbohydrates by limiting refined sugars and processed foods is a modifiable way to manage behavior problems in children.

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