First of all, don't you like it when your dog leans on you? We have seen many dogs who likes to lean on their humans, usually putting their entire weight on the humans. Though it might be a slight problem if your dog is a giant breed.
So what's up with the dogs leaning on people? What we felt that this is a sign of affection and that they want to be closer to people. Because it seems to be a common instinct for us to pat or start massaging them when they exhibit physical contact.
Dogs are smart and they learn quickly that when they get close, they will get pats. And if this action is desirable to them, they will be more inclined to do it more often. Because they love it!
Some of them lean with all their weight, some sit on our feet, some sleep with their paws on us and some wants to snuggle up on the couch or bed.
All of this proves that dogs enjoys physical contact with their humans.
We read somewhere that some people say that this is an action of dominance over humans, but we beg to differ. When dogs lean on people, they do not show signs of wanting to assert dominance in any other way, one example is that she do not like it if you touch her when she is leaning on you. If not, most likely she is not seeking the so-called "alpha dog" position.
If you dislike this behaviour, you can discourage it by just walking away whenever she does it. In time to come, she will learn that you dislike her leaning on you and will slowly stop doing it.
Usually, dogs leaning are harmless and not a worry. So instead of being concerned over the leaning, why not shower your dog with love that she wants since she is probably just asking for a little affection and reassurance that you still love her. After all, everyone likes to be reminded of how loved they are, and dogs are no exception.