Very low calorie diets and hypokalaemia: the importance of ammonium excretion.

Obesity has become a worldwide epidemic and is associated with significant morbidity and mortality. More than two-thirds of adults in the United States are either trying to lose weight or prevent weight gain. Very low calorie diets, diets with energy levels between 200 and 800 kcal/day, are used commonly for rapid weight loss. These diets are generally safe and well-tolerated and have been reported to improve blood pressure, glycaemic control and lipid profiles. Minor side effects, including fatigue, constipation, nausea and diarrhoea, often occur, but serious adverse events, including death, may result if the very low calorie diets are not used appropriately [1]. Hypokalaemia may occur with very low calorie diets but is usually mild [1,2]. Below, we present a case of severe hypokalaemia, which developed after 2 weeks of a very low calorie diet. The pathophysiological mechanisms that lead to the development of significant potassium depletion are discussed.