There are 1 million diet, fitness, weight loss books and methods out there but when we look at the big rocks, there are 3 main ways to lose weight.
Let's look at reducing your energy/calorie intake first.
According to many experts and Asker Jeukendrup, currently a visiting Professor at Loughborough University, UK and the Director of mysportscience, reducing your energy/calorie intake is the most important factor for weight loss.
Low-fat diets and energy restriction result in weight loss and are both effective over the long term.
Against current guidelines, (think low-carb mania) reducing your dietary fat can be very effective for reducing overall calories in and promotes weight loss for several reasons.
1. Fat is very energy dense and has twice the amount of energy as the same weight in carbs or protein.
2. High-fat foods generally taste very good and can lead to a tendency to eat more.
3. Fat is less satiating (less filling) than either protein or carbs.
4. Fat is very efficiently stored and requires very little energy to digest. I know that a lot of people will say "but look a KETO diet, lots of people lose weight with that."
They would be correct but only because there is a drastic reduction in carbs to make up for the increase in fat.
Personally, if you follow KETO, PALEO, ATKINS, OKINAWA WAY, PIOPPI, DUKAN, I don't know really care. If it is working for you, keep with it.
The key principle is that there is a reduction in energy into the body which makes weight loss possible.