Low carbohydrate diets, such as the Atkins plan, can lead to life-threatening conditions, a medical journal warned yesterday. The Lancet described the case of an obese woman who had adhered strictly to the high-protein diet for a month before being admitted to hospital as an emergency.

The 40-year-old, who had taken vitamin supplements recommended by the Atkins plan, needed treatment in the intensive care unit of a New York hospital. She had ketoacidosis, a condition triggered by the liver's production of ketones, the acids which appear during periods of starvation or when there is a lack of insulin in the body due to diabetes.

When first admitted the patient felt nauseous and was dehydrated after vomiting for several days.

She was short of breath and in "moderate distress". Four days later, after a dextrose drip, she was well enough to be discharged.

The doctors said the Atkins diet was largely to blame.

Professor Klaus-Dieter Lessnau, who led the team from the New York School of Medicine, wrote: "Our patient had an underlying ketosis caused by the Atkins diet ... this problem may become more recognised because this diet is becoming increasingly popular worldwide."

The Atkins diet maintains that you can lose weight rapidly by cutting carbohydrates entirely from meals.

For a month before she fell ill the woman admitted to the US hospital had lived on meat, cheese and salads.

She had also taken vitamins recommended by the diet.

As instructed in the original Atkins diet book, she monitored her urine twice daily. During this month-long period, she lost about 9kg (19lbs).

Commenting on the case elsewhere in the Lancet, Lyn Steffen, a doctor, and Jennifer Nettleton, from the University of Minnesota School of Public Health delivered a further warning about Atkins and other carb-cutting diets.

The pair wrote: "While the rapid weight loss seems to be an obvious benefit of the Atkins diet, bigger questions remain.

"First, is the diet safe? ... low carbohydrate diets for weight management are far from healthy, given their association with ketosis, constipation or diarrhoea, halitosis, headache, and general fatigue to name a few side effects.

"These diets also increase the protein load to the kidneys and alter the acid balance in the body, which can result in loss of minerals from bone stores, thus compromising bone integrity."