I wasn't grossly overweight but I'd crept up over the years (I'm ancient, Noonan-class ancient) and have a horrible family history of heart problems. And the fat I carried was all around the stomach, exactly the worst place. So I decided I should lose 6 to 7 kg, which I guessed would bring me down from a 38 waistband to 34. That was two years ago.
The good news is that I lost nearly 6 kg and now can wear 34 trousers, although I'm really a 35. The better news is that I've kept it off, except that this Christmas was disastrous and I put over 2 back on, which I've since just about managed to shed. I'm now working towards losing a couple more to get properly down to my original target.
My method has been the classic combination of exercise and diet. I've settled into a routine of two days cardio (1 hour, running or cross trainer), one day resistance, and one day off; repeat. And for diet the method is to count calories and keep within my limit. I have a sedentary job so it's 1450 calories per day, plus credits for whatever exercise I do. That's supposed to lose me half a kg per week, but as I usually break the limit by 100 or 200, it keeps me level. If I keep strictly within the limit then I do lose weight.
The most useful aids I've got are the Myfitnesspal and Mapmyfitness apps, and a heart rate monitor. I'm going to get a Fitbit Surge HR, which calculates calories burned in exercise and syncs them into Myfitnesspal, to adjust your limit for the day.
It was surprisingly easy to start using Myfitnesspal, which is a calorie counter, and I found it fascinating to learn how many calories various foods have. I now eat far less bread and potatoes than I used to. Alcohol is also a killer: three glasses of wine and I can kiss goodbye to the limit for that day. On the other hand, I love sashimi, and it's a great lunch with lots of protein and not too many calories.
The app tracks other things as well as calories. I watch protein and fibre and try to eat the recommended amounts every day. Unfortunately the fibre-rich foods tend to have a lot of calories, and fruit has a lot of sugar as well.
I've learnt to be very careful of the "special treat". If I have a donut or brownie one day, it's ten times as hard to resist having one the next day, and once they become regular, the scales reveal the consequences.
I intend to keep doing this indefinitely. The exercise is good for me and my arteries and blood pressure, and it's great not to catch sight of myself unexpectedly in a reflection and see the belly as the most prominent feature. I don't really miss the bread and potatoes, and the reduced alcohol has benefits that far outweigh the detriments.
I agree with those who say to avoid the fad diets, and don't expect that your initial rate of loss will continue. And it's true that what works for one won't necessarily work for another. But if you really want to lose weight then you can. You just have to realise that you're going to have to do some things very differently from the way you've done them before, and in particular you're going to have to get used to not having various things, solid and liquid, that you've been used to having and like very much. The good news here is that the longer you do without them, the less you miss them.