Dietary glycemic load, the mathematical product of the glycemic index (GI) of a food and its carbohydrate content, has been proposed as an indicator of the glucose response and insulin demand induced by a serving of food. To validate this concept in vivo, we tested the hypotheses that 1). portions of different foods with the same glycemic load produce similar glycemic responses; and 2). stepwise increases in glycemic load for a range of foods produce proportional increases in glycemia and insulinemia. In the first study, 10 healthy subjects consumed 10 different foods in random order in amounts calculated to have the same glycemic load as one slice of white bread. Capillary blood samples were taken at regular intervals over the next 2 h. The glycemic response as determined by area under the curve was not different from that of white bread for nine foods. However, lentils produced lower than predicted responses (P < 0.05). In the second study, another group of subjects was tested to determine the effects of increasing glycemic load using a balanced 5 x 5 Greco-Latin square design balanced for four variables: subject, dose, food and order. Two sets of five foods were consumed at five different glycemic loads (doses) equivalent to one, two, three, four and six slices of bread. Stepwise increases in glycemic load produced significant and predictable increases in both glycemia (P < 0.001) and insulinemia (P < 0.001). These findings support the concept of dietary glycemic load as a measure of overall glycemic response and insulin demand.

SummaryLow‐carbohydrate dietary patterns are re‐emerging as a popular method of weight reduction. However, their nutritional adequacy to meet the needs of growing adolescents should be considered. This study aimed to design theoretical low‐carbohydrate meal plans for clinical use in the management of adolescent obesity and assess nutritional adequacy. Meal plans were created for three levels of carbohydrate restriction (≤30, ≤50 and ≤120 g/day) without energy, protein or total fat restriction. Nutrient analysis was conducted using the FoodWorks Australia Ltd software (databases: AUSNUT 2013, AusBrands 2017, AusFoods 2017, NUTTAB 2010, New Zealand FOODfiles 2016), and compared with Australian Nutrient Reference Values for male and female adolescents aged 14 to 18 years. All low‐carbohydrate meal plans met the Recommended Dietary Intake, Adequate Intake or Estimated Average Requirements for most micronutrients at an energy intake of 6.3 to 7.2 MJ/day (1510‐1730 kcal/day). The proportion of energy from saturated fat exceeded recommendations across all models (11.3%‐17.1%). Dietary manipulation was required to minimize saturated fat and reach micronutrient adequacy, particularly for calcium in males and females, and iron for females. In practice, this may be challenging considering individual lifestyle and preferences. Therefore, the use of low‐carbohydrate diets with adolescents should be monitored by a trained professional to ensure nutritional adequacy.

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