I think the benefits of "low fat" may have been dulled by how literally people took that message, and what companies replaced the fat with.

Most available "low fat" products compensated by adding sugar. Lots of sugar. That way it still tastes nice, but its healthy right?

Just like fruit juice with "no added sugar" (concentration via evaporation doesn't count) is a healthy alternative to soda right?

In truth your body is perfectly happy converting sugar to weight, with the bonus that it messes up the insulin cycle.

At a fundamental level consuming more calories than you burn makes you gain weight. Reducing refined sugar is the simplest way to reduce calories (and solves other health issues.) Reducing carbohydrates is next (since carbs are just sugar, but take a bit longer to digest). The more unprocessed the carb the better.

Reducing fat (for some, by a lot) is next (although reduce not eliminate. )

Both sides want to blame the other. But the current pendulum is very much on the "too much sugar/ carbs" side of things.