Low-Glycemic Index Foods Reduce Overweight/Obesity in Kids

Kids Who Eat Low-GI Goods are Less Prone to Overweight Issues

We live in a period in which overweight/obesity rates are overpowering normal body weight in kids and adults equally. While dietary factors hold primary responsibility its also our sedentary lifestyle and physical inactivity that play an equal role in triggering excess body weight in kids, adolescents and even toddlers. This excess body weight now exists as one of the biggest medical problems around the world affecting people from all walks of life disrupting their quality of living. Some of the major long-term issues include diabetes mellitus, dyslipidemia, hypertension, sleep apnea, musculoskeletal problems, gastrointestinal disease and psychosocial difficulties. Overweight/obese kids (above the age of 7) have maximum risk of growing into obese adults with increased risk of cardiovascular disease. Even the World Health Organization (WHO) shows that overweight and obesity exist as the leading cause of premature death worldwide and as a serious risk factor for mortality during adulthood too.
Obesity is nothing but body weight ranges well above the defined limits which leads to higher body mass index values and waist circumference. Statistics show that obesity rates in America have more than doubled in the past few decades and the results are almost similar elsewhere too - India is becoming one of the top countries with maximum childhood and adult obesity rates, the incidence of obesity and overweight in the Iranian population is 10.1% and 4.79% respectively and Brazil has experienced a drastic nutritional transition from decrease in malnutrition to increase in obesity/overweight rates. Though genetics and environmental factors do play an integral role in determining obesity risk in kids most researches also show that macronutrient composition of the diet is equally important to maintain normal body weight. Studies focus on dietary fats and carbohydrates too as a factor for weight control.

Carbohydrate Quality Using Glycemic Index
Some of us have heard the term glycemic index while for others it might be something new. It was Jenkins et al. (1981) who used the term ‘glycemic index’ first to define carbohydrate quality. What is this glycemic index (GI)? It is nothing but the ability of the food to increase blood glucose 2 hours after eating that kind of food. According to Jenkins GI refers to the area under the blood glucose curve measured two hours after consuming 50g of carbohydrates with respect to the results obtained by consuming 50g of glucose or white bread. The term glycemic load (GL) was introduced in 1997 to quantify the overall glycemic effect of food with respect its specific carbohydrate content in typically consumed quantities. GL is calculated by multiplying amount of GI with carbohydrate amount in grams. High GI and GI diets are rapidly digested, absorbed and transformed into glucose which pave way for higher chances of glucose fluctuations, early signs of hunger and increased calorie consumption. Meanwhile, a low GI and GL diet takes time for digestion, releases glucose and insulin slower into the bloodstream and increases satiety levels decreasing calorie consumption. Maybe some of you now remember our physician’s clinic or hospital that notifies patients on the list of low GI and high GI foods that need to be consumed and avoided. But studies on the relationship between these indices with obesity rates in individuals come up with controversial results-either supporting, rejecting or showing no changes between the indexes and obesity rates.

A meta-analysis published in 2003 shows that low glucose index (LGI) are advantageous for glycosylated hemoglobin (HbA1c) in type 1 and type 2 diabetics compared to high glucose index (HGI) diets. We do have studies showing that consumption of high GI/GL diets increased the risk of type 2 diabetes. But most of these studies focus primarily on the adult population and the study below shows the effect of LGI and LGL on anthropometric parameters, blood lipid profiles and indicators of glucose metabolism in kids and teens below 18 years of age.

Systemic Review
The systemic review was performed using the electronic databases MEDLINE and EMBASE with search terms such as ‘glycemic index’ and ‘glycemic load’. Apart from keywords other inclusion criteria were that they must be randomized control trials (RCT), age of participant <18 years of age, they must be humans and markers such as BMI, height, weight, waist circumference, hip circumference, waist-to-hip ration, systolic blood pressure (SBP), diastolic blood pressure (DBP) and fasting serum insulin (FI) must exist in the studies.

The search came up with a total of nine studies consisting of 1359 articles and 1065 participants that met the study criteria and was now eligible for meta-analysis. All the nine studies were randomized control trials (RCTs) which had a duration between 10 and 96 weeks. Results showed that:
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1. There was no effect of LGI/LGL on anthropometric data despite an analysis performed only on kids and adolescents who were obese/overweight.
2. Triglyceride (TG) levels significantly decreased in the LGI/LGL group in comparison to the HGI/HGL group but there was no effect seen on rest other blood lipid parameters
3. Measurable decrease in HOMA index (a method for assessing insulin resistance where a lower index denotes increased sensitivity to insulin and a higher index denotes more resistance to insulin) was seen following an LGI/LGL diet compared to an HGI/HGL diet.
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The review shows that an LGI/LGL diet definitely has a positive effect on TG and HOMA-indices in kids and adolescents compared to an HGI/HGL diet. Its noted that an increase in TG levels is a risk factor for atherosclerosis and cardiovascular diseases and, obese/overweight kids and adolescents were noted to contain significantly higher serum TG concentrations. Thus, this study, though it could not show any improvements in anthropometrical parameters such as body weight, BMI, BMI z-score and waist-circumference there was indeed a significant positive impact for TG and HOMA index.

Effect of Cohort Studies on Kids with Obesity
A study split participants into two teams-one team received a diet low-GI diet and the other a reduced-fat diet (emphasis was placed on limiting intake of high-fat, high-sugar and energy-dense foods while increasing consumption of grain products, vegetables and fruits). Though 190 participants were initially included only 107 remained as the others were not regular for follow-up. All the participants received medical evaluation, dietary counselling and lifestyle counselling in the presence of at least 1 parent. Each of them was called for follow-ups every month for the first 4 months and thereon, as and when needed.

In the reduced-fat intake group energy restrictions of approximately 1042 kJ to 2084 kJ per day was imposed compared to normal energy intakes. Macronutrient intake goals were set at 55-60% carbohydrates, 15-20% protein and 25-30% fats. The other diet was designed to provide the lowest GI possible but satisfying all nutrient requirements for kids. Here, there was more importance given to food selection and not energy restriction. This diet varied from regular diets mainly in the macronutrient ration where participants were asked to combine low-GI carbohydrate, protein and fat at every meal and snack. Macronutrient intake goals here were 45-50% carbohydrates, 20-25% proteins and 30-35% fats. Results showed that for each BMI tertile, the low-GI group showed a larger decrease in BMI compared to the reduced-fat group. Also, a larger percentage of patients in the low-GI group experienced a decrease in BMI compared to the reduced-fat group. Kids who were fed with reduced-fat diet showed no change in adjusted BMI whereas children fed with low-GI diet showed a BMI decrease of 1.15. A low-GI diet might promote weight loss by lowering insulin levels.

Effect of GI & GL on Brazilian Children
A study in Brazil conducted to observe the effect of glycaemic index and glycaemic load on hunger and high-energy intake and the risk of overweight/obesity and high adiposity in kids involved 5-year-old children whose adiposity, weight and nutrient index was assessed. GI of every food consumed by the kids was noted down and the kids were segregated into one of the 4 groups-under weight (7), normal weight (185), overweight (38) and obese (2). Overweight/obesity prevalence was 16.2% in the case of boys and 18.9% in case of girls. Meat, egg and margarine contain no carbs and do not contribute towards GI calculations. Only 87.7% of the foods in the food-frequency quantitative questionnaire (FFQQ) contributed to glycemic diet profile and the rest were categorized in the following frequencies: cereals and beans in 3-4*/week, milk/dairy products and sugar-added drinks in 2-3*/week, bakery products/biscuits, vegetables, fruits and sweets in 1-2*/week.

Results showed that kids from families with higher per capita income and moms with higher education levels had better glycemic profiles. Overweight group had a higher median carbohydrate intake than the normal weight group. It was generally seen that kids consumed significantly higher carbohydrate levels. They consumed more of cereals and beans followed by sugary drinks which are high in simple carbs thus contributing to an increased dietary GI. Fruits and vegetables that are low in GI and containing high fiber was consumed in lower proportions comparatively. Also, the cereals consumed were all refined ones. The study showed that the overweight group had higher GI and GL levels compared to the normal weight group.

References
Effects of Low Glycaemic Index/Low Glycaemic Load vs. High Glycaemic Index/High Glycaemic Load Diets on Overweight/Obesity & Associated Risk Factors in Children & Adolescents: https://nutritionj.biomedcentral.com/articles/10.1186/s12937-015-0077-1
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A Low Glycaemic Index Diet in the Treatment of Paediatric Obesity: https://jamanetwork.com/journals/jamapediatrics/fullarticle/350858
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Influence of Glycaemic Index & Glycaemic Load of the Diet on the Risk of Overweight & Adiposity in Childhood: https://www.sciencedirect.com/science/article/pii/S2359348216000129