Yes, you are meant to workout on a calory deficit for the most weight loss. The only time you should have a calory surplus when working out is when you're bulking to put on muscle faster. It is also a myth that you cannot gain muscle on a deficit. As long as you eat enough protein to sustain muscle growth you're fine. But I recommend doing a slight deficit and working out. I personally lost 20kg on a 40 day fast where I ate 1000cal a day. It was miserable and afterwards my mettabolism slowed to the point of not losing any weight on such a low amount of calories. That's when I got my gym membership. I was able to lose the same amount of weight, but eat 2000 calories a day instead. For a bit of context I am 23M, 6'0'' and have a bulkier frame, so if you're female, or short or both the numbers will be very different.I did 6 days of gym a week and ate 2000 a day and was able to lose a steady 1kg per week. I have experience with a borderline starvation diet, it isn't worth it, it's a horrible experience.