research – How to define user’s problem in Clean Eating?

I’m Mai. I’m a totally fresher in UX and recently I’m working on a mentoring project (Product Design) where I need to find a solution to make Clean Eating Journey become easier. But I’m so trouble in finding their true pain points (like the one that most deserves to be solved). I’ve conducted a survey, interview and even diary study but their answer are so general, I couldn’t come to any conclusion. I guess maybe my Interview technique has gone wrong.
Do you have any ideas/solutions that might help me? I’m so stuck on this, thank you very much!