Keto diet has not been shown to reduce weight any more than a calorie restricted diet in the long run, however, many people find it easier to restrict carbs short term which may result in more rapid weight loss initially. Much of the initial rapid weight loss has been shown to be due to water loss which is a associated with the depletion of stores carbohydrates. Adding exercise has not been shown to assist much in weight loss but is associated with weight maintenance and an increase in insulin sensitivity. Diet and weight loss is complicated as your body will regulate resting energy expenditure based on the new caloric intake. After a lot of reading and learning I get the idea that focusing on healthy living with mild calorie restriction and increased exercise works in the longer term and that this may be supplemented by the addition of short term diets designed to drop fat faster. As always, discuss this with your doctor as any weight loss diet should take your medical history and individual needs into account.
As someone who lost over 160KG, Low carb diet of your choice diet, 50grams of carbs per day MAX, no fucking sugar ever. You may find high fat low carb (ketogenic) easier or low carb high protein (paleo-ish diet), do your research. Also any type of weight training or body weight exercise will help you keep your lean mass.