Melanocytes could intervene in fat metabolism for muscles in the following way.
Melanocytes may be related to the temperature of the seasons and the temperature of the blood to keep fats in a very liquid state and optimal for the muscles.
When blood temperature drops, muscle becomes harder and fat molecules become more solid. In this case the melanocytes stop generating heat.
When we play sports and consume 150 grams of fat in an hour, a tan could occur and if we do not consume 150 grams of fat per hour, the tan is less even if you go out in the sun.
On cloudy summer days you can say that the sun rises when you consume 150 grams of fat and loses its strength depending on how you recover from those calories.
When melanocytes and blood temperature drop, the fat molecules become harder and it facilitates rest, sometimes with anxiety, until it gradually warms up and facilitates the formation of atmospheric water.