Children under the age of five should exercise for at least three hours per day to prevent becoming obese, new UK guidelines suggests. The British health department said in its latest report that children under the age of five, including babies who can't walk yet, should exercise every day. "The evidence suggests that physical activity, especially in the form of play, during the first five years of life is a basic and essential dimension which must be fostered, encouraged and provided. Conversely there are many opportunities for young children to spend excessive time in sedentary behavior which should be limited and replaced with more physically active options," wrote Chief Medical Officers for England, Scotland, Wales and Northern Ireland. They urged parents to take their children for swimming sessions, and let them stretch and play on activity mats. Even toddlers should walk for at least 15 minutes for any routine journey, such as to and from nursery. "For children that are not yet walking, there is considerable evidence that letting children crawl, play or roll around on the floor is essential during early years," said England's chief medical officer, Sally Davies. "Play that allows under-fives to move about is critical and three hours a day is essential," she added. "I think there are parents who are not aware how important it is for their children to be physically active for a minimum of three hours. Other parents are very busy and may not see how important it is to get that prioritization and balance right." The new guidelines come amid fears over globally growing childhood obesity and links between lack of activity and brain development disturbances. Children should reduce their sedentary behaviors by spending less time in baby bouncers, strollers and car seats, along with watching television and playing video games, the report added. Since 1980, the prevalence of obesity has doubled in adults and tripled in children. An estimated 42 million children under the age of five are overweight, 35 million of them living in developing countries, according to the World Health Organization (WHO). In addition, the rate of obesity has more than doubled over the past 20 years in most EU countries as more than 15 percent of the adults suffer from the problem. Reportedly, each year more than 35 million people mostly in low and middle-income countries die from non-communicable diseases such as cancer, diabetes and cardiovascular conditions, which have a strong association with obesity.