Sinus bradycardia was observed in 10 adolescents participating in a we
ight loss diet conducted in a health centre, The precise cause was ass
essed. The subject's age ranged from 10 to 15 years and weight loss ra
nged 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, Infect
ion was suggested since 8 of the 10 adolescents had a rhinopharyngitis
a few weeks before the discovery of bradycardia, This cause was not r
etained 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 cont
aining less than or equal to 1350 kcal/day, This hypothesis was suppor
ted by the results of work reported in 1970 showing arrhythmia in very
low calorie diets, The effect is essentially related to the biologica
l value of proteins in the diet, its duration and the initial weight o
f the subjects, In addition bradycardia is frequently seen in subjects
taking hypocaloric diets or with anorexia nervosa and should be consi
dered as an adaptation to hypometabolism rather than a true heart diso
rder. Thus the biological value of the proteins and the mineral status
should be taken into consideration during the course of low calorie d
iets, even though bradycardia is frequent and does not require a speci
fic treatment Therefore heart rate and decreasing rate of weight loss
should be carefully followed during the course of low calorie diets.