As someone who has had multiple obese people in the family (grandparents, uncle) and myself who lost 11 stone I can certainly say that it is possible. There are numerous routes you can take as many have outlined already.
I lost my first two stones doing Keto (Low carb) in three weeks (water weight included) and then transitioned to a VLCD with my doctors supervision since my hunger was killed after going low carb. 700 calories a day was pretty easy. I did this for 3 months and lost an additional 5 stones. So 7 stones in around 4 months, I went from 26 stone to 19 stone. From then on I did a combination of VLCD days and higher calorie (no more than 1200) keto days. From 23 stone on wards I'd try to walk 2-4 miles a day 5 times a week and just continued until I hit 16 stone then went to the gym and I've been pumping iron ever since.
My grandmother did SW and went from 19 stone to 10 stones in just over a year. My grandfather who "WAS" diabetic with type 2 did Keto for over a year and went from 23 stone to 15 stone in just over a year, was cleared of his diabetic medicine and can now enjoy a balanced diet again.
The one thing I'd say is that regardless of what method you choose, eating real food is the key. Whilst I did go the VLCD route because I just HAD to shift some of the weight quickly, going Keto made me pay attention to cooking meals from scratch. Likewise, my grandparents also started off by simply cooking from scratch and avoided as much processed food as the possible.
Zero drinks and no added sugar squash were my lively hood and didn't cause my to have any cravings so you should be good with that. I will say though, not having junk in the house was a major help. If I was hungry, I had to COOK lol, no microwave dishes or frozen Iceland meals. It meant getting out some meat and seasoning from scratch.
Oh yeah, MyFitnessPal and a food scale are so helpful. As for my Uncle he's just started to calorie count and has lost 13lbs in a month. Still has treats here and there but always has a healthy dinner and he swears by downing 2 tablespoons of Apple Cider Vinegar before sweets snacks to stop his blood sugar from rising and causing more food cravings. I take it too since I have noticed I feel full for longer after having some before lunch (If I'm at home) and dinner. It has to have "The Mother" in it as well