However, lettuce and other green leader vegetables are generally very high in quality nutrition and very low in calories so you can have an ENORMOUS green salad (all kinds of different salad leaves) and you would be pushing it if you ate 200 calories.
Or you could have a Danish pastry or doughnut with virtually nothing of nutritional value in it and have eaten 300+ calories.
You can therefore eat tons of low quality foods that make you fat and unhealthy and STILL not be getting adequate nutrition. So you feel hungry and unsatisfied.
Eat lots of fibre (loads of veg. esp green veg) fruit, and whole wheat, plus legumes (beans, lentils). You really do not need much of any kind of animal products such as meat, eggs and dairy on a weekly basis. A small amount a few times a week is fine.
If you drink soda such as coke it has tons of SALT in as well as sugar so ou will end up feeling thirstier and hungrier if you drink it. Also the caffeine in coke makes you pee out any free water so you want another drink. It's basically not food but just crap that doesn't give your body anything you need except then we wonder why we are overweight?
First easy thing to do is just drink fresh water - no soft drinks or wine etc (for a while, when you want to lose weight) water has 0 calories and is what your body wants! Most other drinks (except fruit/herb teas with no milk) have lots of calories. You're drinking yourself chubby.