Why are there no traffic lights for calories?

The four nutrients food manufacturers label with traffic lights are fat, saturated fat, sugar and salt. Eating too much of these nutrients has been associated with negative health outcomes, such as cardiovascular disease. Energy per se is not associated with specific health risks, so there isn't a traffic light guide for 'Kcals'. However, it is still important to pay attention to the calories in your food to make an informed choice, especially if you are trying to lose or gain weight.