[Torchwatch]

In the 1970s and early 1980s American and British people were slim, they swam in speedos and played sport in short shorts. Then Coca Cola swapped out cane/beet sugar in it's drinks with fructose based corn syrup. This was intended as an ingredient cost saving but they discovered that where previously people were satisfied with one can or bottle of Coke they now demanded 2 or more drinks.
A food scientist studying this discovered that there was an optimal balance of sugars, fats and salt in food products that made the food irresistible but unsatisfying, you ate the meal but were left hungry, and went back for a second helping.
If you try to eat a tub of lard or a bag of sugar your body will say stop we're full, but if you make a delicious fat/sugar balanced cheesecake you'll keep eating it until it's gone and want more, especially if you swap out the sugar with corn syrup.
Everything you buy at fast food shops and all the processed foods you buy at the super markets have this scientific fat/corn syrup/salt ratio that allows you to keep eating and never feel full.
Suddenly in the late 1980s American and British people started putting on weight and wearing big shorts for swimming and sports to hide it. Rather admit that they were putting on weight they declared wearing speedos and short shorts was gay.
There was a sportswear fashion change because the food scientists altered everyone's food without them knowing so they'd eat more and still not be satisfied.