The suggested period is about 10 -14 days. You need to increase your Basal Metabolic Rate. The combination of run-weight training-cycling/swimming is meant for that precisely.
The main issue is not the subcutaneous fat, rather, it's the visceral fat, that is, the one around your internal organs. To target that, you need a sustained program of exercise as also careful diet balance. The aim is to eat everything and more frequently but in smaller portions and at regular intervals along with increased BMR.
How your body consumes energy is broadly - carbohydrates, if shortage, use proteins, if shortage, use fats. Now this is the broad biochemical pathway. So you have to target this pathway.
When you increase your tempo of exercise from walking to running, you are increasing your BMR. Coupling it to weight training with emphasis on reps and NOT load increment, will increase your BMR at micro level in muscles too. That shall help in greater mobilisation of your 'reserves of energy' which will be fats, even long after you have actually stopped physical activity. Cycling as far as you can on road (and not gym) or swimming if you can for about 500 meters will further accentuate this.
Remember that the body needs only 30 mins for restitution and it is fit to go, but the brain needs 8 to 10 hours to reset itself, hence our sleep is 8 to 10 hours. The sleep itself is more to do with brain's restitution than body's.
So, concomitantly, reduce carbohydrates. I am saying reduce not eliminate it. Your Oats/porridge will provide you with adequate Carbs as also various fruits (your brain uses Glucose and only as last resort shifts to Ketones). Then you need to increase your proteins in order to compensate for various pathways in body. So, when you are doing your weight training and exercise, your protein intake will be diverted to remodelling of your muscles at microlevel to compensate for increased activity. The reduced availability of carbohydrate derived glucose and proteins will force the body to mobilise reserves of glucose - which are stored as fat. Hence, the suggestion as above.
If you go on a hunger strike, the worst time is from 36 to 48 hours, when you feel the hunger maximally. Thereafter, the body's 'scavenging' pathways kick in.
Keep your microsurgery off here, the problem with surgeons is, they miss the broader picture. ... there is no requirement of a 5-0 here, not doing a LIMA CABG
If you could not get it, it is ok. We can write it off to neurofibrillary tangles somewhere, eh?
Who it was meant for, got the message.
Have fun!