Video: Brown fat measured by thermal imaging The thermal imaging technique avoids the potentially harmful radiation which has been used in previous studies to measure brown fat in adults, and which has prevented scientists accurately measuring brown fat in children for safety reasons. By using the new technique on children as well as adults, the researchers demonstrated that children have larger stores of brown fat and produce heat much more rapidly than adults. Dr Budge said: "Brown fat does appear to be present in higher amounts in larger people than in people of lower body weight, but we think the key difference is in how active it is from person to person. "The reason this is exciting is that if you "switch on" brown fat and it uses up energy, then potentially that is one way of controlling body weight." Further studies of how brown fat responds to different food groups could enable food manufacturers to include a new category of health advice on food packaging, the researchers added. Prof Symonds said: "Potentially we could add a thermogenic index to food labels to show whether that product would increase or decrease heat production within brown fat. In other words whether it would speed up or slow down the amount of calories we burn.