@hamstersarse I agree things like food environment have a lot to answer for but also poverty, lack of a decent nutrition education and many other factors
I'm vegetarian and I mostly cook from scratch inc making my own sauces, I'm in a decent home and my income is ok at the moment but I still can eat more than my body needs calorie wise if I'm not very careful - and even when I AM careful I can gain weight which is incredibly frustrating!
It's also things like pots and pans are bigger than they used to be, plates and bowls and even cutlery is HUGELY bigger than it used to be, I have small hands and a weak grip and I have real trouble finding cutlery I can manage. I've mentioned on here before my mum is still using a 1970's dinner service (which is an achievement in itself especially as dad was army and it's been moved over 20 times! 
) when I was doing ww a few years back the leader mentioned bigger plates and out of curiosity the next time I went to mums I took a dinner and side plate of mine, hers were half the size! Mine don't even fit in my cupboards properly! I've tried finding smaller services but they're out of my budget the cheap plain white ones are massive.
I put a normal, healthy portion size on one of my dinner plates and I'd say it barely covers 1/3 of the plate So it looks like there's sod all on there!
How low is your low budget though? Cos there were times I had £10/15 to do me a week for dd and I both. It was those weeks I mostly didn't eat at all.
I'm a confident cook, I understand nutrition pretty well having been at school when this was still taught and having a mum that was skilled at shopping and cooking for a family on a budget and taught us too but there's only so much you can do when money is very tight or you're in a less than ideal home as I have been on several occasions due to problems with income and mental health issues.
You would think that not eating = lose weight but it really doesn't always I had this very discussion with my dr and she explained the complexities in relation to meds I'm on and how it messes with metabolism.
I've certainly met people who really don't feel at all confident cooking from scratch especially with meat let alone offal (I'm veggie but I can cook meat it doesn't phase me) hell I've met people who won't "cook" anything beyond a microwave meal or freezer to oven stuff cos they're afraid of getting it wrong and causing upset stomachs or having a meal wasted.
Imo one of the worst things removed from the curriculum was proper home economics where kids were taught to cook from the basics and budgeting for food and the nutritional aspects involved as I was.
But yea the way food shops are laid out and stocked... the green grocery part is one of the smallest depts and certainly where I live it's the same old stuff just different varieties of the same thing - eg 20 different kinds of potatoes rather than a wide variety of different veg.
Now I know they'd argue other veg wouldn't sell but I bet they would if promoted and we had eg govt public service ads inc recipes etc
It's woeful how all this is not addressed
Demonising certain foods I don't think is useful either that's gone on for decades! I'm old enough to remember when all fat was considered evil and then we had people not consuming enough healthy fats and that caused health issues. Everything in moderation, certain foods need to be consumed together in order for optimum absorption of nutrients to occur, and things like blood sugars kept in check.
I haven't had a takeaway or a microwave meal in over a year, I don't really like chocolate, or chips, or fried food very much generally I eat healthy foods...just it used to be too much of them and too much of the calorie dense parts like carbs and fats but I haven't cut those out just I'm now eating correct portion sizes and having more veg.
The dismissive attitudes to the Mh issues around all forms of unhealthy eating on this thread is quite shocking from certain posters - except not as I'm used to seeing mental illness treated dismissively in our culture despite the campaigns to "be kind" etc
I think we have yet (as a society) to properly catch on to the idea that over eating (generally not binge eating) is very very often associated/connected with Mh issues and very often ime related to trauma/previous abuse.