My first guess is that those who were young adults of the 80's were raised in a lower carb, higher fat culture - not LC as such, but they didn't have the fat phobia and carbs pushed on them from the time they were little kids, so if they ended up gaining a lot of weight, they didn't gain it as early in life.

The young adults of today have had low fat and high carb pushed on them from shortly after birth. My theory is that if you start that sort of diet earlier in life, then you're going to suffer the consequences of it earlier in life too.


Since they've been eating a healthy low fat high fiber diet, of course no one can possibly figure out what's causing them to gain weight on less food with more exercise.