Although some, no, most, will tout this or that "diet" and claim great results there is only one way to lose weight; assuming you have weight to lose. That is to have a calorie deficit. In other words; make sure the calories burned are more than the calories consumed.
Over the long term, not some short term crash thing, to maintain acceptable weight and fitness one must have a healthy lifestyle. A healthy lifestyle includes exercise and nutrition. (The word "diet" is actually a word of death as we use it).
For years I was able to maintain my weight and fitness at acceptable levels. Then, I changed work and social settings. I felt I was a bit fat and soft but persuaded myself I actually was doing fine. My reference was to look at others around me. A fitness exercise gave me a wake up call. It wasn't that I was doing good. It was that the overwhelming majority of the people I saw on the street were doing so bad.
I started biking. I rode spin bike in the winter and on off days during the summer. I also took up serious weight lifting to build muscle mass and with it more strength and endurance. I changed my food intake back to high protein, low fat and finished out my calorie allowance with complex carbohydrates. This eliminated about 85% of everything in the supermarket. All this staying within my calorie allowance.
The result is that over 2 years I lost 20#, increased my fitness to the point I can easily ride 25 miles over hill and dale with a lolngest so far of 55+ miles in 3 1/2 hours. I am well on the way to taking off another 10# and riding my first century this summer. I have concentrated on fitness and not weight. The weight loss came along with the fitness.
To date I have never met, nor heard of, any person who did not do the same thing and who succeeded over the long term.
Face it most people are Fat and Unfit. Most people are looking for the quick fix; take a pill, use a short term diet, etc. In fact there is no substitute for good exercise and a proper diet with foods as close to nature as possible.