I can not stay on a diet?

i eat like crazy like you think you can eat not like me im literally always hungry like take this for example this is what i just ate for diner not all day just dinner Chinese food 6 burritos a bag of chips oh and a whole plate of brownies a Arizona tea and some coconut juice but i don't really get it im not fat but im not skinny im 5 feet and weigh 120 pounds but i don't really have a chubby stomach i have pretty chubby thighs though like the way i eat people say i should be obese so like are there any tips to stay on a diet and not eat as much because i heard its unhealthy