my food is just random stuff from the fridge
If staying under carbs/cals limits you have set, then no problem - all power to you!
But important to understand exactly how much/little you're consuming, and eating only from verified recipes helps with that. Ham & cheese omelette on page 20 equals 340 kcals, stir-fried cabbage with peppered mackerel on page 30 equals 280 kcals, etc. Don't have to think about it.
Most people don't lose weight on plans despite "eating less" not because diets don't work but because of failure to accurately perceive/record true amounts being eaten. Have done it myself many times - kind of "tweak" results to make the day look better. Makes me feel bit more comfortable, doesn't help me lose weight.
One of many papers on the subject:
"The main finding of this study is that failure to lose weight despite a self-reported low caloric intake can be explained by substantial misreporting of food intake and physical activity."
Another one on our collective inability to estimate intake, though far from unique to Brits:
"Britons are consuming 50 per cent more calories than they think they are, according to new research from the Office for National Statistics."