We purchase a specific brand of Instant foods, Soft drinks etc because of pressure of the situation. True?

there is no such diet drink it part and parcel of the marketing strategy and by diet there is never any change in the body change or health. According one should go for regularly food & drink [milk /water / and lot fiber and natural food and avoid smoking drinks & drug and diet drinks

Yes. it is true depending on the urgency and availability we buy.