This comment is a little late, but as someone who has had 17 piercings altogether, has 7 currently, and is quite well-versed in the art of piercing, I just had to weigh (teehee) in. Okay, so the thing about navel piercings is that they can be kinda finicky and you have to have a certain navel to ensure longevity. For a navel piercing to last, there should be a little overhang of sorts. Here's a quick album I made to show what I mean. As you could see in Achtung's album, the person's fat was pierced. It isn't sitting where it should and the jewelry is of very shitty quality. The butterhuffer can look forward to rejection, migration, irritation, etc. So if a fatty wants a navel piercing that MIGHT last, they'd need to use a certain type of jewelry called a J-curve and will need to be pierced deeper. It should also be noted that sometimes thin people aren't well-suited for navel piercings, either, especially those with outies. But when you're thin, you have better options. A J-curve is one of them, but some thin people will choose a surface anchor (sometimes referred to as a 'dermal') or an inverse navel piercing instead! The more you know...