I have a suggestion for a sidebar widget. There are now online tools for The Hacker's Diet, though honestly this plugin rivals them, and this is much easier to install rather than relying on a third party service.
However, one thing would be nice. The online tools provide HTML code for inserting an image displaying one's weight, trend, etc. Maybe you could develop something similar, maybe displaying at least the trend, and maybe how much above the goal weight one is, and the expected date of reaching that weight, kind of like is in the dashboard. Just an idea.