When you go on a diet, try not to set unrealistically high expectations or goals. Doing so places unnecessary wear and tear on you, especially on what you think about yourself, on your watchfulness of yourself, all of which can lead to you being too self-critical.
For example, you can be self-critical for just having slips in your thinking. It goes like this -
thought:"I feel like cheating."
Even if you don't actually follow through and cheat, you may fault yourself for just thinking this way. Or you might think of a forbidden food and lose hope.
The underlying process has to do with spoiling your mental readiness for making this important weight change in yourself. By setting unrealistically high standards, you keep the pressure on yourself to not even think wrong.
If you believe you must work at suppressing or ridding yourself of your unwanted thoughts, pressure like this can lead to depletion of your good thinking, your
mental resourcefulness, and you will be placing an unnecessarily heavy
burden on yourself.
Such an increase in self denial could lead to compensating yourself in other ways like compulsive overeating by having seconds and even thirds or other forms of emotional eating like bingeing on junk food.