Some models use sunless tanning products to maintain a year-round tan, as it’s not always possible to get regular sun exposure. Sunless tanning products work by applying a colourless solution to your skin that contains DHA (dihydroxyacetone). This reacts with the amino acids in your skin to produce a brown pigment. The results usually last for around a week before you need to re-apply. Others may use tanning salons and sunbeds to keep on top of their tan.