It is possible to make your face look thinner by using a few different types of makeup, namely foundation, concealer, and bronzer. Certain types of blush, applied correctly, can make your face look thinner as well. The key is to create the appearance of contours; a defined jawline, and high cheekbones, for example, will always give you a thinner appearance than if your face appears completely round or square. The basic idea to contour your face is to provide a lighter foundation shade all over the face, and then a slightly darker shade to create the appearance of shadows and bone structure.
When you are attempting to use makeup to look thinner, it is necessary to begin with a smooth palette. Apply concealer as needed, to areas of redness and darker areas under the eyes. Then, apply a smooth liquid or powder over the entire face in a shade that matches your natural skin tone, and blend it well along the hairline and jaw. This will even everything out and make you look wide awake and healthy. Some beauty experts then advise using two different shades of foundation to create the contoured look, but depending on your face shape, you may be able to just use one, or even some well-placed blush or bronzer.
You will want to choose a foundation that is just a little darker than the first layer of product, and therefore a little darker than your natural skin tone; apply it to areas where contours would naturally appear. Experts typically advise applying this contour shade lightly under the cheekbones, to make it appear as if you have higher cheekbones, as well as along the jawline. This will mimic the appearance of shadows, and immediately make your face look thinner. It may take some practice to achieve a natural look with this, but once you master it, it is quite effective.
Some people will then add one more step to help the face look thinner, either with a bit of bronzer, or a lighter shade for highlighting purposes. These shades, rather than being applied to the side of the face, are applied to the front such as the forehead and the chin. Again, this should be applied very lightly in order to look natural. The theory behind this is that they will call attention to the narrower part of the face, and appear to highlight the areas where the sun would hit naturally, giving the skin a healthy glow.