There are far too many complex and fancy diets around, that just confuse everyone.
Losing weigt is a simple matter of eating well, but eating less than your body actually needs.
Most adults need about 2000 (female) to 2500 (male) calories a day. Eat more than that and you put on weight, eat less than that and you lose weight.
Some foods are obviosuly bad for you such as - sausages, creamy curries, sweets, biscuits, pork pies, food cooked in fat, crisps, mayonaise and so on. Just dont eat ANY of them. Look at the fat content of everything you buy.
Most fruit and vegetables are good for you so eat plenty of them.
Avoid sauces on food, and try to avoid procesed food and "ready made meals" (usually full of fat and calories). Try to eat a breakfast, lunch and dinner each day.
Try to do more light exercise, walk round the block each day, that sort of thing. Dont go "mad" with exercise or you weill never keep it up.
Weight takes a long time to put on, so it can take a long time to take off. Dont go for "quick fix" diets but change your eating habits and look to lose the weight gradually over a number of months or even years.
There are to many people who want a "quick fix" with a diet but it should really be a long slow process.