A ketogenic diet is an effective weight loss strategy for many. (caloriesproper.com)
That said, there are downsides to it as well, and I certainly don't think it's the best fat loss strategy for everyone, all the time. (straightforwardfatloss.com)
High fat diets are also useful to slow a strong appetite, and when eaten with lots of vegetation can be an effective weight loss strategy for some. (foodasmedicine.ca)