The reason behind obesity is overeating. Figure out why people eat to excess because there are a whole myriad of reasons.
Speaking as someone who used to be obese, I did not fit the stereotype. I did not eat ready meals or "processed" foods (hate that term). I was brought up on home cooked food and am an excellent cook myself, cooking most meals from scratch using fresh ingredients and loads of fruit and veg. I love veg.
Three things were the issue with me. One, my portion sizes were humongous. I am only 5ft2 and a portion of pasta for me would have been about 120g, double what it should have been. The second issue was emotional eating - my reaction to any emotion, happy or sad, was to eat. If something good happened, I'd want to celebrate with food. If something shit happened, I'd want to comfort myself with food. I was never hungry because I just ate all the time and it didn't matter that the food I ate was "healthy". Thirdly, my mother whom I adore but who has huge issues with body image never let us have sweets, fizzy drinks, fast food or anything like that growing up so when I went to uni I went nuts and had loads of it. Feeling it was forbidden made it harder to resist.
I tried all diets, including blood sugar and all types of low carb high fat, but ultimately none of them eliminated the above problems, particularly the second and third ones.
I am now maintaining a healthy weight (3 years now) because I finally tackled those problems and my disordered eating. I see no food as "bad" now. I eat bread, pasta, sugar, full fat dairy, junk food occasionally if I fancy it. But my portion sizes are appropriate for my height and sex and, most days, I don't snack.
Today I had a blended frozen banana with greek yoghurt, honey and chocolate nut butter for breakfast. Lunch was 3 scrambled eggs with red pepper, spinach and pepper, followed by an apple. Dinner will be home made red lentil dahl with paneer and a home made naan bread. May have an ice lolly too!