Normal cardiac rhythm during hypocaloric diets of varying carbohydrate content.

Cardiac arrhythmias have been implicated in the deaths of 17 morbidly obese individuals subsisting on a collagen hydrolysate preparation ("liquid protein") during a modified fasting regimen for weight loss. Serious cardiac arrhythmias have been noted in three of six subjects studied prospectively within 28 days of starting a similar regimen, which used an inadequate protein source and was nearly devoid of all essential minerals. A comparative study of three 28-day weight loss diets of varying carbohydrate, protein, and energy content (450 to 820 kcal/day) but employing protein of good quality and adequate in micronutrients did not disclose substantial diet-related arrhythmias in five subjects on each of the three diets. The incidence of arrhythmia seen with liquid protein diets is not likely to be related to the absolute energy or carbohydrate content of the modified fasting regimen itself.