The anti-diet movement has been around since the 1960’s

At the centre of the anti-diet movement are two scientific claims.

1. The relationship between weight and overall health is unclear. It’s possible to be a healthy fat person and an unhealthy thin person.
2. Dieters end up gaining back all the weight they lost.

The data on the first claim shows it to be mostly true. A 2014 meta-analysis showed that 6 % - 75 % of those classified as obese were “metabolically healthy.” 

Studies on the second claim show that it is very rare for dieters to lose weight and maintain that weight loss.