Singel Arm:  Thirteen overweight premenopausal women aged 32 to 45 years consumed <20 g carbohydrate/day with liberal intakes of protein and fat for 2 weeks; thereafter, carbohydrate intake increased 5 g/week for 10 weeks. Serumhydroxybutyrate was correlated with presence of urinary ketones, but no relationship was found between weekly weight change and serum ketone production. Urinary ketones are detected in premenopausal women complying with a low-carbohydrate/high-protein diet and are associated with serum ketone concentration.