Keto can be used as a weight maintenance tool. If you don’t have too much to lose and struggle to maintain a low carb approach year-round it can be done this way.
The downside of moving from a high carb SAD (Standard Australian Diet) to Keto is you will need to go through the fat adaption phase each time you move your energy systems.
Keto is more than just a fad diet; it is a way of teaching your body to use a ‘new’ energy system, fat. It may be a better idea to maintain a low carb (modern Keto) way of eating all year round but allow your carbs to creep up to 100 or 120g per day from time to time. Then drop them down again.
This way you will have all the health and performance benefits of Keto but still enough flexibility to not feel ‘trapped’ by your way of eating.
If you want to drop a significant amount of weight quickly and are prepared to be disciplined you can do so by dropping carbs below 20g per day and increasing your fat intake to 70- 80% of total calories per day. Many people will adopt this method to get in shape for a major event, like a wedding, or if they need to lose weight for medical reasons.