Honestly I do think 2-3 cokes and Maccas twice a week probably does more damage than you'd hope. Eating those instead of water/a home cooked meal probably runs you an extra 4-5,000kJ a week in fat and sugar which, if consistent will see weight gain.

But obviously it depends on how active you are, plus I don't think it's up to the supermarket to ensure that people eat healthily.