Obviously reducing fat intake is healthy, so long as sugar isn't used as a substitute for fat, to add taste. Unfortunately, a few "low-fat" products such as low-fat yogurts, in Australia at least, focus on reduced-fat labels (e.g. 70% less fat or non-fat) for marketing purposes, but don't mention that fat taken out has been replaced by adding sugar. They have high sugar content, so won't really help you lose weight, nor are they 'healthier'.
The other point, HFCS is not widely used in Australia and in for example soft drinks. Instead we use cane sugar - here it is thought that when the body turns HFCS into energy, it creates too-high levels of the unhealthy triglyceride fats in the process. So, even though too much sugar is not good for us, the body seems to handle it better than HFCS.
That is what Lustig also claims, but not sure if Mase, who bitterly disagrees with his overall thesis, agrees.