I suspect most people don't weight themselves on a regular basis, they're motivated more by their looks rather than an objective measure like weight. Since looks are subjective it's easy for them to dismiss the issue for a while. It's only when they cross some boundary when they can no longer lie to themselves that they've put on weight will they step on the scale, and by that point they realise they have a substantial task ahead to get back to a normal weight. Many prefer denial rather than face up to the issue.