Totally agree the diet industry is evil, and I also think most of these low calorie ready meals are a waste of time, they are low in calories yes but they are not always healthy and don't fill you up.
Losing weight is very simple, all you need to do is find out what a healthy weight is for you height/age/gender is and what daily calorie intake is needed to maintain that weight. Whatever that daily calorie intake is, then that is your limit.
As long as you always have a calorie deficit below the calorific needs to maintain your current body weight than you will lose weight, this can be helped along with a good amount of exercise.
Also the most important thing is to learn about nutrition there are many foods out there that people assume are healthy but are not at all healthy. Bread for instance is high in calories, especially white bread so always eat wholemeal, same with pasta and rice always opt for wholemeal. If you like to eat potatoes, buy sweet potatoes, they are a complex carbohydrate and have slow release energy and taste great too. Obviously it goes without saying but eating plenty of veg especially dark green veg like spinach and broccoli is very good for you, and helps you feel full. Having a good source of protein is also essential, skinless chicken breast, fish such as mackrel and very lean red meat which helps with iron intake.
Starving yourself, and depriving your body of its needs with silly soup diets is never a good idea because when you starve your body you will lose weight. Though once you resume a higher calorie intake your body then holds onto to it as fat stores because it has previously been starved and it doesn't know when its next meal will be so it keeps it as reserves. This is why when people lose weight drastically often end up putting it back on plus some extra.
All that's needed is:
Healthy Diet
Portion Control
Exercise
Sorry for the long post....I have a bad habit of doing that eek!!