Hmm, I came across some short and simple hadiths. Wanna know a remedy for keeping your diet in check apart from exercising? Just hold on to the words of this hadith (prophetic tradition) tightly..
نحن قوم لا ناكل حتى نجوع واذ اكلن لا نشبع
translated : We (muslims) are a nation which do not eat unless we're hungry and when we eat, never till we're full.
Basically, just don't keep feeding yourself 24/7 and eat as if you want to fill up every single space in your body. Short, simple and effective, insya-Allah.