Thank you for your interesting question. Dietary choices certainly can affect how healthy your skin looks, and your nutrition often determines how well your skin is equipped to deal with damage from environmental factors, such as sun damage.
When it comes to the diet, your skin will benefit most from foods that alkalize the body, such as fruits, vegetables (specifically leafy green vegetables as discussed in my blog "3 top foods for wrinkles"!), nuts, and legumes including chickpeas and lentils. Many nutrients present in fruits and vegetables, including carotenoids, flavonoids, lycopene, and lutein, can protect the skin from damage, which may dry out the skin and promote the development of wrinkles.
In addition to this, wholegrains may play a part in keeping the skin looking youthful. They help to support the barrier between your skin and the environment, as well as trapping moisture in cells to keep the skin hydrated, which can give your skin a "plumping" effect. Good quality sources of protein, though these are usually found in acidic foods, are also essential to keeping your skin looking healthy. Protein is an essential component of collagen, which gives your skin structure, therefore lean sources of protein such as salmon or chicken can help to keep your skin firm.
However, consumption of certain acidic foods, such as refined sugars, processed foods, alcohol, caffeine, cola, and red meats, should be limited. Processed foods and refined sugar can actually attach to protein in the skin and cause it to break down, leading to wrinkles and skin which looks older.
So, whether you have a few wrinkles already, or are still fighting them off, your skin will immediately benefit from a diet rich in fruits and vegetables, wholegrains, and lean protein, and should provide the plumping and firming affect you are looking for!