Children whose parents lack warmth are more likely to grow up overweight or obese, according to the first study of its kind. The effects of different parenting styles on children’s weight have been determined for the first time – and suggest parental warmth is key to a healthy weight, researchers at the International Congress on Obesity in Melbourne, the biennial congress of the World Obesity Federation, will say on Wednesday. Their analysis of data on 10,000 children in the UK found authoritarian and neglectful parenting in early childhood were linked with higher weight throughout childhood and adolescence. Both types of parenting are characterised by a lack of warmth. “The effect of parenting style on a child’s weight is often considered a taboo subject,” said researcher Alexa Segal, of the Centre for Health Economics & Policy Innovation at Imperial College London. “However, a comprehensive understanding of the associations between parenting style and childhood and adolescent obesity has great potential to inform obesity policy and contribute to the development of more effective health and nutrition programmes.” Child obesity is a growing problem worldwide. In England, more than a quarter of four- and five-year-olds are overweight or obese. Researchers used data from the Avon Longitudinal Study of Parents and Children to look at the association between parenting style during early childhood and a child’s weight later in childhood and in early adolescence, late adolescence and early adulthood. Parenting style was divided into four categories based on questionnaires filled in by the parents and children. The four styles examined in the study were: authoritative (parents who maintain clear boundaries but are also warm), authoritarian (parents who maintain strict discipline and show little warmth), permissive (parents who are empathic but have few rules) and neglectful or uninvolved (parents who are emotionally uninvolved and have few rules). The analysis of two decades of data on 10,510 participants showed that youngsters who experienced authoritarian or neglectful styles of parenting in early childhood were more likely to have a higher weight than those who experienced authoritative parenting. The results for permissive parenting were not statistically significant. The lack of warmth associated with authoritarian and neglectful parenting may mean that a child’s ability to self-regulate their food intake – to eat when hungry and stop eating when full – does not develop properly, the researchers said. “Authoritarian mothers are characterised by being demanding and controlling, while having low warmth and responsiveness,” said Segal. “This could lead to them not responding to their child’s hunger cues by, for example, not allowing them to select a snack when hungry, and/or asserting control over the child’s food intake by, for example, putting them under pressure to clean their plate when they are not hungry. “This control means that the child does not develop their own ability to regulate their own energy intake, meaning they might overindulge when they have the ability. “Neglectful parenting, on the other hand, may be an issue of true neglect, where no rules are given – so children might have a free rein to select unhealthy options.” Prof Louise Baur, the president of the World Obesity Federation, said: “This study highlights the fundamental importance of parents in raising healthy children. “The world today often makes it difficult for children and families to eat well, be physically active, sleep well and cope with stress. Parents who are able to set appropriate limits for their child, while bringing warmth and sensitivity to the relationship, may be better able to help their child be as healthy as possible.” A second study presented at the conference found that people who put on just under a stone (6.35kg) in weight in midlife are significantly more likely to need a knee replacement. Women who put on 11lb (5kg) are a third (34%) more likely to need a total knee replacement, while men have 25% increased odds. The study, led by Monash University in Australia, found that even relatively small weight gains can increase a person’s chances of knee osteoarthritis, the most common cause of knee pain, and the need for a knee replacement.