Factors Influencing Body Mass Index, Appetite Control, and the Role of Glutamate and Excess Nutritional Protein During Child Development: A Review

Michael      Hermanussen; Jesus   A. F.   Tresguerres

Abstract

Obesity has become a major public health concern in this century. Yet, the widespread popularisation in managing overweight and obesity indicates that the problem of body weight maintenance has developed from an only medical into an interdisciplinary and already political problem. Current ideas about lifestyle and strategies to maintain health and weight have become dominated by increasingly popular beliefs that contrast scientific evidence. Particularly the relationship between physical activity, energy intake and body mass index (BMI) explains markedly less of the within-population variance of the BMI than commonly assumed. Instead, it has been noted that protein consumption significantly correlates with BMI explaining up to 13% of the BMI variance in young adolescents. Increasing evidence suggests that nutritional protein can stimulate food intake. Serum levels of most amino acids increase following a protein rich meal. Regions of the brain that are involved in the regulation of appetite accumulate glutamate and other small molecules. Free glutamate can be toxic for some of the essential neuronal structures of hypothalamic appetite regulation, may impair satiety and result in voracity. Protein toxicity in humans occurs at amounts beyond an intake of 200 g/d. Protein intake needs supplementation either by carbohydrate or fat in order to reduce its contribution to total energy intake to less than 40%, and the protein content of many popular high-protein weight loss diets must for the same reasons be regarded with great caution, and should particularly be avoided during pregnancy and childhood.

Keywords: Body mass index, appetite control, protein, obesity, glutamate

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