Gender differences in health and illness In developing countries, most studies show preferential food allocation to males over females. Nonetheless, some studies have found no sex differences in the nutri- tional status of girls and boys (20-22), and others have described differences only at certain times of the life- cycle. For example, research in rural Mexico found no nutritional differences between girls and boys in infan- cy or preschool, but school-going girls consumed less energy than boys. This was explained by the fact that girls are engaged in less physical activity as a result of culturally-prescribed sex roles rather than by sex bias in food allocation (23). Studies from developing countries of gender differ- ences in nutrition in adulthood argue that household power relations are closely linked to nutritional out- comes. In Zimbabwe, for example, when husbands had complete control over all decisions, women had signifi- cantly lower nutritional status than men (24). Similarly, female household heads had significantly better nutri- tional status, suggesting that decision-making power is strongly associated with access to and control over food resources. Access of women to cash-income was a positive determinant of their nutritional status. In rural Haiti, the differences in nutritional status for male and female care-givers were examined for children whose mothers were absent from home during the day. Those who were looked after by males, such as fathers, uncles, or older brothers, had poorer nutritional status than chil- dren who were cared for by females, such as grandmoth- ers or sisters (25). Ethnographic research conducted by the authors revealed, however, that, while mothers told the interviewers that the father stayed home with the children, it is probable that the father was, in fact, absent most of the day working and that the children were cared for by the oldest child, sometimes as young as five years of age. The involvement of both men and women in nu- tritional information and interventions is key to their successful implementation. Unfortunately, in most de- veloping countries, women are selected for nutritional education because they are responsible for the prepara- tion of meals. However, they often lack access to nu- tritional food because men generally make decisions about its production and purchase. Similarly, men may not provide nutritional food for their families because they have not received information about nutrition. The participation of both men and women is, there- fore, fundamental to changing how decisions about food are made and food-consumption patterns and nutrition families (26). The study in rural Haiti referred to above also found positive outcomes through the formation of 49 men’s groups which received information on nutrition, health, and childcare. These men, in turn, were resourc- es for education of the whole community (25). The gender differences are also found in the social determinants of nutrition in industrialized countries, al- though their manifestations are different. For example, gender plays an important role in determining risk fac- tors for eating disorders, which influence nutritional out- comes. The most common of these are anorexia ner- vosa, bulimia nervosa, and binge eating (BED) (27-28). The root causes are only partly understood. Biomedical and psychological theories include hormonal imbal- ance, malfunctioning of serotonin in the brain, genetic explanations, and emotional problems expressed by ab- normal relationships with food. Sociocultural explana- tions include the emphasis placed on the ‘ideal’ female body shape in western society. Experts agree that a key factor is the desire to please others. These character- istics are linked to ‘negative femininity’—behaviours associated with passivity, dependence, unassertiveness, and low self-esteem. Dieting and bingeing may be used for improving body image and self-esteem. Concern with body image is particularly strong in adolescence where the differences in calcium intake and a more sed- entary lifestyle are pronounced (29). Results of a study of 1,755 adolescents in the United States also showed that, during adolescence, intake of fruits and vegeta- bles was generally low for both boys and girls and that their consumption was related to consciousness about controlling their weight (30). Among men, dieting and bingeing seem to be more common among gay men and sports competitors than in heterosexuals (31). Many studies have demonstrated the effect of so- cial support on nutrition in older adults, with a positive impact being seen among those who are married, espe- cially men (32-34). This has been explained by several factors—the greater likelihood to skip meals when liv- ing alone, or to eat filling but unhealthy products and snacks. Women who are alone may not be able to af- ford an adequate diet, or they may be less motivated to cook for themselves when they are accustomed to providing for others (35-36). The gender differences in nutritional risk were stud- ied among an older sample of black and white com- munity dwelling residents in Alabama, USA (37). The study took into account social support, social isola- tion, and social capital as possible determinants of nu- tritional risk. Social capital was defined to include neighbourhoods, trust people felt in their security, and religion. The study found important gender and racial differences between different groups, black men being