As a parent of 2 children who have been overweight, about which I was 100% judged, I feel I can say with some confidence that it's a very complicted issue.
My children's weight issues were for different reasons. DS has ADHD and SPD. He was very overweight and it was very concerning for us. His weight was the result of a combination of simply eating too much and not enough exercise. He was a good eater, and we ate healthily, but the volume of food he needs meant that we were inadvertently giving him way too many calories - and he was ALWAYS asking for more food (thanks ND).
This was exacerbated by the fact that he wasn't moving as much as he should - he did extra curricular etc, but it's that constant, low level movement that's important. we put the effort in - encouraged a lot more independence so he was out and about more, found new sports groups with a focus on longer sessions and fitness, and shifted a lot of what he ate so that he could still have large portions, but they were lower calorie. Luckily, he's a brilliant eater so he doesn't care fi his plate is full of salad or full of mashed potato - he'll eat it! He's now a very tall, very sporty, very slim 14 year old who just won full colours for sport at school.
DD was notably overweight, albeit nowhere near as bad as DS. She has food intolerances, only some of which we've got on top of, and some other minor health conditions. This combination has also led to her being an annoyingly fussy eater. Her doctors have consistently assured me that she's fine, but I have worried a lot.
But again, like DS, we've encouraged a lot more movement - she attends dance classes, we get out and about a lot etc. Slowly I'm trying to introduce a more balanced diet. She's also much less bloated and prone to "holding weight" which I see defintiely happens when she IS bloated. And she's growing. She's not where I want her to be, but she's well on track.
The point is that it's complicated. And the judgement doesn't help.
Oh, and the 23% of children are overweight or obese figure? I have serious doubts about that. After DS lost all that weight AND had another growth spurt - to the point me and teachers were keeping a very close eye on him for an ED as he was starting to look TOO thin, I received the dreaded letter telling me he was obese. I couldn't believe it.
So I went digging... the NHS admits themselves that BMI figures for children who are tall or short are not necessarily helpful. Pity they didn't figure that out when they sent me the letter. If you put his weight and height at age 10 into the BMI calculator but said he was 12.... it said he was 50th percentile, and perfect. That's because as well as being on the 97th percentile for weight, he was on the same percentile for height.