Go on a Ketogenic diet. I lost 14 kg in two months. Thereafter it flattened out and lost about 1 to 2 kg per month. Better still, almost all of that loss was round the middle. I had to buy a new belt this Saturday last. Exercise is good and from what I understand it works well with the diet, but 80 to 90 percent of weight loss is due to diet, rather than exercise. (I also had a lot more energy, but part of that may have been due to my rectifying an electrolyte imbalance. ) I also went from a pre-diabetes A1C to normal A1C in those two months.
In concept you are forcing your body to burn fat rather than glucose. There do not appear to be any downsides if you do the diet correctly. My only downside it that I have to take care to get sufficient vitamin C. What you do on this diet is two-fold. 1 You avoid sugar / carbs. 2 You eat a very wide spread of cruciferous vegetables. Veges that grow above ground is another guideline.
In avoiding carbs / sugar; you
Have zero alcohol. Strangely not difficult for me who obsessed about my single malts. I also loved a good Cabernet.
Have zero sugar. Ie cakes or any product where sugar is an ingredient.
Very low fruit. This is because of the sugar (fructose) in fruit. I currently eat lemons, limes, avocados, tomatoes. Very tiny quantities of berries and pumpkin (technically a fruit).
Very low carbs. So zero grains such as bread, wheat, oats, pasta, rice. The only carbs I have are the residual carbs in the veges and other food I eat.
Meat, fish, poultry, eggs, dairy (cream, not milk based) are all good.
There is tons of stuff on YouTube. One thing that you will be told and is worth repeating now is to clear the mind of the concept that 'fat is bad'. Like everything in life too much of anything is bad for you. Fat is not bad for you. It is essential for life. Many vitamins are not water-soluble and must have fat to enter into the system. Fat (and protein) also satisfy hunger. So I for example am on two meals a day with no snacks. I do not have pangs of hunger. If I do get peckish I have a cup of coffee with cream. That takes away any feeling of huger for a couple of hours.
This not a fad diet and not a reworking of the Atkins diet (replace carbs with fat and protein). It is based on getting full nutrition.