A 16-year-old female client is admitted to the hospital because she collapsed at home while exercising with videotaped workout instructions. Her mother reports that she has been obsessed with losing weight and staying slim since cheerleader try-outs 6 months ago, when she lost out to two of her best friends. The client is 5’4” and weighs 92 lb, which represents a weight loss of 28 lb over the last 4 months. The most important initial intervention on admission is to: