I would make a “Do More” goal, and call it something like “Following Eating Plan” or even just “Eating better”.
I would say the “unit” is “days”, and every night before going to bed, or in the morning if you tend to eat late night snacks or something, I would either enter a 1 or a 0. 1 means “I stuck to my eating plan”, and 0 means “I did not stick to my eating plan.”
I would set your “rate” to be an easy number for now, like 3. That means you have to stick to your plan for 3 days a week, and any days you stick to your plan beyond that count as safety buffer for later. (Being absolutely perfect would be a rate of 7, which means 7 days per week.) After you get into a good habit of entering your data, I would increase your rate to something more like 6, which means you get one “whoops” per week, or 6.5, which would be one “whoops” every 2 weeks.
(You can also choose to get a free week of safety buffer at the beginning.)
Also, if this is one of your first goals, the first time you “derail”, or mess up, you actually don’t have to pay, but the second time, you do! (Also, don’t worry. If the derail is due to a mistake or you messing around with the website trying to learn, you can email them after a derail and they won’t charge you for it.)
If you stick with it, and find out you have too much safety buffer and need to get rid of it or you won’t actually make progress on your goal, throwing away your safety buffer is called “retroratchet.” It is easy to accidentally derail when retroratcheting, but the support team has your back and can help you out.
Phew! (I really like Beeminder… I have lost nearly 40 pounds since February!)