One possible counter argument to that is, yes it possibly could be, by the outlets being there anyway, allowing temptation to be there, and also people wanting the food, by what the food is. If Hamburgers had a filling of say Hummus, how many people would eat them then?
Woudl be a nice way ot get some Carbs and healthy Fats in your food, but the taste could maybe be likened to a deep fried dog turd, or something like that.
I read a comment by someone once, saying they used to eat that stuff sometimes, but owing to them moving house, to a location that was nowhere near a Fast Food outlet, they hadn't eaten any for about 3 years.
True people will eat it if it's there, and often of their own free choosing, and I admit I've done it before and would again if I felt like it, but I'm in control, and coupled with my lifestyle, occasionally having one or two hamburgers without trimmings, won't send me or my body up the creek without a paddle.
Also seductive merketing doesn't help. That's why Britain has now adopted, a no junk food ads before 7PM rule, on channels with advertising based incomes, in order to reduce the ability of children to watch such ads.
At least some junk food people have tried to change their ways.
I must commend the Walkers Crisps people, for their efforts in the last 4 years to do this.
Their Crisps now have less Salt, about 70% less Saturates, and contain Sunseed. So they may now have product you could reccomend as a now and again thing, without some parents thinking oh heck what am I letting my children do?
Funny enough briefly on the subject of ingesting bad things, one guy many months ago in Britain, e-mailed a news network, (who had asked on air for peoples views about Fizzy drinks), and said he didn't think the drinks represented a risk to his kids teeth, as he made his kids drink the fizzy stuff with straws, as he put it, "allowing the Sugar to bypass their Teeth."
The response of both presenters was pretty much, I doubt that, but nice to think so all the same

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You are totally right though, people eating it is pretty much voluntary. Marketing however seductive is not subliminal, or done with some kind of "Clockwork Orange" style brainwashing treatment, (Malcom McDowell may eat Fast food, I wouldn't know

), nor is marketing done with people coming round to your house, and then forcing fried meat down your throat by assaulting you, or making you do it with a Gun to your head.
Problem is though, the alternatives.
You could go somewhere like an eatery, or restaurant, that might be open at 12:00PM, and might serve say a Steak and a Baked Potato, effectively a Beef and Carbs alternative to Hamburgers, but you'll pay at least about £6.50 for the meal no doubt, and depending on the Steak cut you order, up to £10.50, rough price range for a good standard outlet. Obviously snootier outlets possibly with a no child policy, you'll pay over the odds.
For the same amount of Beef and Carbs at Mc'D, probably about £1.95 or less, for two Hamburgers and no trimmings, both scenarios exclude a drink, and probably at least 10 minutes less waiting time, so for price and convenience, Fast food places will win out, even if better alternatives are available during things like workers Lunch breaks.
P.S. Good to have you on board

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A good body comes from hard work.