hose of you who are thinking about doing a ketogenic diet have some incredibly serious reading and studying to do. You have to know how many carbs your body requires to enter ketosis... no more, no less. You have to know when your body is in ketosis and what to look for, and how long you have to be in ketosis to reach optimal fat loss. Not only that, but you'll be wasting away muscle the first week or so as well.
As for the 1 set to failure, your muscles need MUCH more stimulation than that to grow. Try doing 3-4 sets, the last set always repping until failure.
Lifting weights is an integral part of losing fat. More muscle = higher metabolism = lower bf%. If you plan on doing just cardio to lose fat, you can say goodbye to any extra muscle you have too. Lift weights prior to cardio exercise.
And don't forget to eat. Eating is good, especially carbs. Your body NEEDS carbs, and depriving your body of it can lead to serious health risks. Eat 6-7 small meals a day, and eat until you are no longer hungry. Eat good foods, like oatmeal, meats, veggies, etc. etc. I worry about a lot of people "trying to get back into shape" and doing it very dangerously. Many people are looking for a short-term fix. Fitness is a life-long lifestyle, not just a 1 or 2 week fad. If you only plan on doing something until you lose an inch or two, you might as well just stop right here. If you are serious about it, then you better get your ass in the gym 5 or 6 times a week.
Imagine how awesome your body would be if you spent even a fraction of your time in front a computer at the gym. While you are sitting there getting fatter, somebody is at the gym getting stronger, leaner, faster...