I’m the same age and same weight and eating 1000-1200 a day and if I try to increase I pile the weight on 😢

Very common, my wife was similar. I have managed to get her upto 1700 calories a day now, count your calories religiously, everything that goes in your mouth gets counted, even the 5 calories in a diet coke. Increase your daily calories by 50 per day, stay there for 7-10 days, then add another 50, this worked for my wife who was eating 800c a day at one point and couldn't loose weight.

is your goal to build muscle, gain psychological/mental health benefits, regulate hormonal issues, or to improve running as a skill lie sprinting or marathon running? It really depends on your goal, the type of cardio you do, and if your body has already been adapted to this cardio, as to how you can reverse diet with it. For instance, we all walk every day. Walking is cardio, but I dont actively take any extra steps so the cardio I do do, my body has adapted to with the amount of calories and macros that I eat, therefore, I can reverse diet without having to count my walking into my actual workout plan. The type of cardio also matters. Aerobic exercises such as jogging/running that are low intensity and long duration sends the opposite hormonal signal to the body that resistance training does. It tells your body to become more efficient with its caloric intake (meaning to hormonally slow the metabolism down in order to accomplish a long aerobic activity of 1+ hours). Aerobic activity burns the most calories from fat at the time of the workout, yes, but over time will also pair down any muscle mass that isnt required in the activity. In running for example, and yes there are different intensities of running, but lets consider your average person who jogs at low-mod intensity for a long duration of 1 hour each day: in this case, having less muscle means you can move lighter and more easily for an extended period of time, and also means your body will require less fuel to go farther. Since we know that the more muscle you have the more oxygen and glucose it uses, the body will naturally pair off muscle over time, which decreases the basal metabolic rate, as a response to become better at the particular aerobic activity of jogging. Combined with a caloric reduction diet, this jogger may lose 25-50+ pounds in a few months. However, this leaves them with less muscle mass and a slower metabolism, meaning once they come out of the diet, and begin eating more or go back to “regular” calories again, their basal metabolic rate is unadapted to this intake, cannot burn this many calories at the resting (non-active) state, because they have decreased their muscle mass. This means that long duration, low intensity cardio in combination with reverse dieting (which is an increase in calories), would lead to fat gain and muscle loss. Reverse dieting should be for those on a weight lifting or strength training program with the purpose of building muscle and increasing the resting metabolic rate. Otherwise, it doesnt make much sense. My suggestion is if you want to fit added cardio (cardio in addition to everyday normal walking) into a reverse dieting plan, that the cardio be any intensity you want (high intensity is best) but keep the duration low at 30mins or less per session. If you begin gaining fat or losing muscle, you’re going to have to eat more or cut down on the cardio sessions.