FASTING during the day and eating a large evening meal may raise levels of high density lipoproteins (HDLs) - the 'good' fats which protect against heart disease - say researchers at Ben Gurion University, Israel. In a study of a tribe of Muslim Bedouins, they found that HDL levels were higher during the religious festival of Ramadan, when Muslims abstain from food and drink during the day and have a large communal meal in the evening. When the Bedouins resumed their normal diet of three or four meals a day, HDL levels dropped by up to 30 per cent, the researchers write in the American Journal of Clinical Nutrition.