As you say look at your diet, drink more water and or herbal teas( I do this when I feel hungry just in case it was thirst not hunger !) instead of caffeinated drinks.
I often have my last meal of the day at around 7pm and not eat again till 8 or 9 in the morning. Also look at the Hay way of eating, it's not a CC diet it's just a slightly different way of eating. Works well for weight loss.
There are exercises you can do yourself for your chin too. Google them!