please,give me a break. anyone who drinks 2 litres of coke will not stop drinking 2L of coke if it didn't come in a 2L bottle. they will drink 6 cans of coke instead.And if you make the container smaller,they will drink more of the smaller kind. Same with fast food. If you make the meals smaller,they will order more.
The problem isn't the product. The problem is people over consuming things. They are over consuming things because its convenient,cheap and tastes good. Peope work all day,the last thing they want to do is go home and make dinner.
But that's what makes the sugary drink ban so effective - it makes people realise that what they're doing is unhealthy. People are much less likely to order two smaller drinks, so they'll either buy a diet drink, stick with the smaller one or get something different altogether. Anybody buying two drinks to get around the ban cannot be under the impression that what they're doing is healthy.
People have become used to large portion sizes in western culture—particularly in America but also in the UK—and something needs to be done to break that psychological barrier. If people are hungry they will often order the largest portion size, even if they don't actually need or want that much. If you restrict the calorie content of meals and drinks then anybody wanting to exceed it has to order two meals, which is where a lot of people draw the line. It's hard to appreciate the level of denial that takes place in people who are overweight, as they often play down how much of an issue it is. Social pressure is very effective at changing peoples habits and if they're effectively made to hold up a sign to the world saying "I'm a fatty because I'm ordering two drinks" then some people will change.
The sugary drinks ban needs to just be the start, though. Restaurants need to be serving portion sizes that are medically healthy - there is no good reason as to why they should be serving 1,500 calorie meals (including drinks and sides) to an average person. I appreciate that some people have greater dietary requirements (i.e. bodybuilders, athletes, etc) but making them order two meals isn't an issue because they know it is healthy for their body. A lot of people simply don't realise how unhealthy a lot of the food is that they're ordering and some gentle social pressure can make a bit difference.