Social class and adolescent obesity First, the good news: childhood obesity in the US has plateaued, recent research shows. Now, the bad news: a new study reveals a significant and growing class gap between the well-off and disadvantaged. In a study published today (Tues jan 14) in the Proceedings of the National Academy of Sciences, Harvard University researchers found that between 1999 and 2010, obesity began to decline among higher socioeconomic status youth but continued to increase among those of lower status. The better-off also had higher levels of physical activity and a greater decrease in caloric intake compared to disadvantaged youth. The researchers used data from two long-term US national health surveys, the National Health and Nutrition Examination Survey and the National Survey of Children’s Health. More vitamin D produces stronger babies Children are likely to have stronger muscles if their mothers had a higher level of vitamin D in their body during pregnancy, a University of Southampton study has found. This greater muscle strength is likely to track into adulthood, says lead researcher Dr Nicholas Harvey, and potentially help to reduce the burden of illness associated with loss of muscle mass in old age. Among nearly 700 mothers in the later stages of pregnancy, high vitamin D levels were related to higher grip strength in the child. High, but not dry Contrary to a commonly held belief, drinking up to four cups of regular coffee a day may not upset the healthy fluid balance in your body. New research from the University of Birmingham's School of Sport, Exercise and Rehabilitation Sciences, published in PLOS ONE, shows that moderate coffee drinking does not result in dehydration, and in fact contributes to daily fluid requirements just as other fluids do. Fifty male participants were tested in two phases, separated by a 10-day wash out period. First, they drank four mugs (200 millilitres) of either black coffee or water per day for three days, then they switched. The researchers found no significant difference in total body water or any of the blood measures of hydration status between them.