New Delhi: Intermittent fasting may help shed some extra kilos in the short term, but such regimens may not be without their risks, a new study, published in Diabetes & Metabolic Syndrome: Clinical Research and Reviews, has suggested.Intermittent fasting involves limiting the hours for eating to a specific number of hours each day, which may range from a 4- to 12-hour time window in 24 hours.In the study, researchers who analysed long-term health outcomes for close to 19,000 US nationals with varying daily eating durations found that participants who ate for less than eight hours per day had a 135% higher risk of cardiovascular mortality (death due to heart and blood vessel diseases) compared to those with a typical 12-14-hour eating period.Further research is required to understand whether the risk of cardiovascular mortality is attributable to the short eating duration itself or residual confounding resulting from its contributing factors, the study says.Dr Anoop Misra, chairman Fortis C-doc and the editorial head of Diabetes and Metabolic Syndrome: Clinical Research and Reviews journal, said people who follow intermittent fasting tend to eat whatever they want in the non-fasting period, including junk food. “Some studies have shown increased low-density cholesterol (LDL) in such cases is a known risk factor for cardiovascular mortality,” he said.The enthusiasm for intermittent fasting must be tempered with careful risk assessment. “Until more long-term data are available, especially on hard outcomes like cardiovascular events (e.g. heart attacks), intermittent fasting should be individualised and ideally supervised, particularly for people with pre-existing health conditions, and applied for short term only,” the doctor said.Nutritionists say extreme dieting can lead to long-term nutritional deficiencies, including proteins, vitamins, minerals & electrolytes. “In some cases, sudden death due to arrhythmias (irregular heartbeat) and chronic inflammation are also possible. Magnesium deficiency can lead to serious cardiac events,” Dr Ishi Khosla, a clinical nutritionist, said.