For products that have a visible effect, these ads show your customer the tangible difference the product makes in their lives.
Note: Facebook ad policy states that “Ads must not contain “before-and-after” images or images that contain unexpected or unlikely results. Ad content must not imply or attempt to generate negative self-perception in order to promote diet, weight loss, or other health-related products. Ads for health, fitness or weight loss products must be targeted to people 18 years or older.”
In other words, don’t do this with any health-related or ingestible product.