All kinds of cake are not Junk Food. Some cake is Junk Food. You can easily differentiate between them if you know What is cake and What is Junk Food.
What is cake?
According to the dictionary, Cake an item of soft sweet food made from a mixture of flour, fat, eggs, sugar, and other ingredients, baked and sometimes iced or decorated.
Froot cake is not junk food.

Another definition According to the dictionary,  Cake is an item of savoury food formed into a flat round shape, and typically baked or fried.
Example:  a starter of goat’s cheese and potato cakes

What is Junk Food?
Junk Food is that kind of food which is pre-prepared or packaged food that has low nutritional value.
Example: I was eating too much junk food.

potato cake is a kind of Junk food.

Many people are keep debating about considering a dessert cake junk food or not. But it’s a food with less nutrients and more calories. It’s clearly made from the sugar and fat. My favorite website regarding food says that it doesn’t come easily in the category of healthy food. But still we can conclude it by considering cake. More than junk food. For healthy cake recipes have a visit at Living Foodz website.