Eating too much is the cause of obesity. If you consume more energy than you expend in physical activity, you will gain weight. There's a big fuss right now about whether it's carbohydrate or fat that causes people to get fat. But i think there's a vast amount of evidence that eating too much makes people gain wat really, it's that simple. Large proportions definitely have more calories. We love sugar. Everybody would be healthier eating less sugar.