I've lost 4 stone since the middle of July (just over five months) and certainly expect to have lost another stone by the middle of Feb, so if you're starting off very overweight and have the right, positive, mindset now then I think five stone in eight months is actually very comfortably managable.
I've been doing a very simple take on intermittent fasting (18:6) - no complicated rules, just no calories in the fasting hours, eat lunch and dinner in the eating hours, and mostly but not entirely avoiding bread and processed sugar and mostly avoid snacking on anything but unsalted nuts and fruit. Since October I've also been walking an average if 6km per day (some days 3km, some days 12km, some days 6km, depending on work shifts and kids etc.)
That's it really - no money paid out to the diet industry, no Apps, no gym, no equipment except walking clothing, no calorie counting. For me the key is to keep it simple and not over think. I do still drink alchol a few nights per month, adjusting eating window to fit.
However I also finished a very stressful life phase pretty stressful life phase in early July, and essentially a switch flicked in my brain and I was just mentally lighter and ready to soet my health out - I hadn't had head space to cope with one more thing before that, and was stress eating, which I was just able to stop overnight when the stress ended.
Good luck - its very possible.