That’s new research from Wake Forest Baptist Medical Center. They found that eating foods high in iron, like red meat, increase appetite. Because iron suppresses production of leptin, the “I’m full” hormone. Leptin also slows our metabolism. And know this: Iron is the one mineral that our body can’t eliminate naturally. So, the more iron you ingest, the lower your leptin levels, and the more likely you are to overeat. So if you’re mysteriously gaining weight, try cutting back on red meat.