Overdosing on dairy
In recent years, a series of studies has suggested that dairy products, especially milk, can cause pimples, whiteheads and blackheads in people prone to acne. Researchers have theorized that naturally occurring hormones in milk stimulate the production of sebum and pore-clogging skin cells [source: Bowers]. Some experts have criticized the studies linking acne to dairy, noting that research subjects had to self-report their breakouts [source: Pappas]. Still, if you struggle with hormonal acne, which tends to appear on the chin or along the jaw line, you might consider cutting out dairy as an experiment.