Evidence presented by leading scientists at the British Nutrition Foundation’s (BNF) ‘Satiation, satiety and their effects on eating behaviour’ conference in London, shows that energy density the energy (or calories) per gram of food, may provide a key to tackling the alarming rise in obesity. By 2050, it is estimated that over a half of UK adults, and about a quarter of all children under 16 could be obese. Understanding how we can manipulate the energy density of the diet can help us maintain a healthy body weight, says Bridget Benelam, Nutrition Scientist at the BNF. We can trick ourselves into feeling full. By changing the energy density of a meal we can achieve the same feeling of satisfaction, while eating less energy than we would usually.Energy densityDr Barbara Rolls, from Pennsylvania State University, has conducted extensive research into the effects of energy density on feeling full. Speaking at the conference she said: Focusing on the energy density of the diet is an effective way of controlling hunger and reducing energy intake. A study of obese women found that a low fat and low energy density diet was more effective for weight loss over one year, than a low fat, higher energy density diet. These women lowered the energy density of their diets by eating more water-rich foods such as fruits and vegetables. They ate more food by weight, felt less hungry and more satisfied, and lost more weight. It looks like energy density is a route to a healthy weight in the long term; research has shown that a low energy density diet aids weight maintenance.To calculate energy density of a food, simply divide the amount of energy (calories) by the weight of food in grams: for example, a 180g sandwich with 360 calories would have an energy density of 360/180 = 2 calories/gram. BNF advises people to eat mostly foods that are either, very low (less than 0.6 kcal/g), low (0.6 to 1.5 kcal/g) or medium (1.5-4.0 kcal/g) in energy density, and consume higher energy density foods (4-9 kcal/g) in small amounts.To help people put our advice into practice weve developed a chart, showing the energy density of a range of foods and dishes, says Benelam. Have a liquid lunchA low energy density diet can be achieved by eating more foods with a high water content; this includes dishes where water is added during cooking, such as soups and stews, foods like pasta and rice that absorb water during cooking, and foods that are naturally high in water, such as fruit and vegetables. According to research from the US, soups can make you feel fuller than the equivalent amount of solid food. But the BNF advises people not to assume that the same effect can be achieved by just taking a drink with a meal. Studies suggest that liquids need to be added to foods or dishes to make an impact on the feeling of fullness. Some initial research using smoothies even suggests that just adding air to food/liquid can help you feel full.Bulking upResearch has also shown that people tend to eat the same weight of food each day. So, if we reduce the energy in the food but keep the weight of the food the same, we consume less energy without feeling hungrier.Fill up on fibreChoosing more high fibre foods is also important because fibre helps to keep energy density low. Also speaking at the BNF conference, Professor Rob Welch, of the University of Ulster highlights the value of fruits and vegetables as sources of fibre Not only are fruits and vegetables high in water and low in energy density, but they are also rich in fibre, which can impact on feelings of fullness in a number of ways.Go easy on the boozeMany people forget to count the calorie cost of alcoholic drinks when watching their weight but they should also be aware of alcohols effects on appetite. Research shows that drinking alcohol before or during a meal can stimulate appetite and encourage people to eat more!Following the tips from the BNF can help you reap the rewards of a low energy density diet. Sara Stanner, Science Programme Manager at the British Nutrition Foundation says: you can lose weight without eating like a rabbit! Try bulking up your meals with low energy density foods. Add more vegetables to a spaghetti Bolognese, eat bread rather than dry crackers, have a chocolate mousse rather than a chocolate bar, or add more salad into your sandwich. She adds Focussing our attention on the energy density of the diet could pay huge dividends, in terms of encouraging a healthy body weight.