Eating less and less food to lose weight is a nasty cycle. I've been on that ride before. Your body is designed to adapt and survive. It will learn to survive on less food (you can only give up so much). And guess what? In case of a famine your body decides it would rather hang on to the fat and give up the muscle. So cutting your calories dangerously low or for an extended period of time eventually backfires. I'm convinced my long ago time period of eating as little food as possible blew my metabolism. Your body needs an adequate amount of good, nutrient dense, clean fuel for general operation, and even more so to power you through your workouts. So as tempting as it is to start slashing calories right and left, it's a wild cycle I would not recommend. Start first with cleaning it up and getting compliant.
Another thing to remember is that just because you lose weight, it doesn't necessarily mean that weight was fat. Hmmm.
So, for me, looks like it's more work.
More work doesn't have to mean longer work. Ramping up intensity may do the trick, such as lifting heavier, adding more sets or reps, or even doing combinations of heavy lifting plus circuits and intervals. Interval training has been shown to be very effective for fat loss (hallelujah!) and when done right it's a lot of work in a little bit of time. The beauty of interval and other metabolic work is the bang you get for your buck in terms of continuing to burn calories after the actual workout. This helps blast fat. Newbies do not need to be intimidated by resistance training or interval training. Even beginners can do it. Some of the most effective exercises are the basic ones you've been hearing about for years, and if you are just starting out you can get results from using your bodyweight for resistance. Squats, deadlifts, lunges, step-ups, rows, presses and chin-ups can do wonders. Same is true of interval training. You don't have to do wind sprints. It's relative to your level of fitness now and can progress over time.
In addition to intensity, it may truly boil down to adding more work over the course of a week to keep your metabolism fired up. I find that while 3 days of resistance training a week is effective for me and necessary for muscle recovery, it's not enough total activity for me. I am my leanest when I keep the burn going by incorporating work on the resistance days that revs my metabolism up and then adding interval training and/or select body weight workouts on the off days to keep that fire going.
Lastly, we've just got to get up and move and spend more time on our feet than on our backsides. Now it's time for me to get off the computer and go do something.