[Bradycardia during treatments of weight loss]

Sinus bradycardia was observed in 10 adolescents participating in a weight loss diet conducted in a health centre. The precise cause was assessed. The subject's age ranged from 10 to 15 years and weight loss ranged from 8 to 24 kg over a period ranging from 8 to 23 weeks. None of the subjects had taken drugs with a bradycardic effect and search for toxic agents in the blood and urine was negative in all cases. Infection was suggested since 8 of the 10 adolescents had a rhinopharyngitis a few weeks before the discovery of bradycardia. This cause was not retained due to the lack of any signs of infection or inflammation and negative virus serology. Nutritional status was therefore retained as the most likely cause in these adolescents who were eating a diet containing < or = 1350 kcal/day. This hypothesis was supported by the results of work reported in 1970 showing arrhythmia in very low calorie diets. The effect is essentially related to the biological value of proteins in the diet, its duration and the initial weight of the subjects. In addition bradycardia is frequently seen in subjects taking hypocaloric diets or with anorexia nervosa and should be considered as an adaptation to hypometabolism rather than a true heart disorder. Thus the biological value of the proteins and the mineral status should be taken into consideration during the course of low calorie diets, even though bradycardia is frequent and does not require a specific treatment. Therefore heart rate and decreasing rate of weight loss should be carefully followed during the course of low calorie diets.