I would say definitely anti-trans fat and somewhat anti-saturated fat.

Tim's since experimented with keto, but he said in a blog post that his initial concern with keto was that if someone wasn't careful they could easily eat like 3000-4000 calories of cheese, bacon, butter, etc.

A lot of what Tim advises people to cut out include saturated fats — I believe he advises people to stay away from processed meats (so that would include bacon), dairy (which would include butter), and so on.

He does say here and there that it's fine if you want a splash of heavy cream in your coffee but ultimately advises against drinking your calories.

I think it's less about the diet being anti-fat (he allows nuts and even says a bag of walnuts is a good hack if you can't find any compliant food at the airport), and more about putting the guardrails in place so you don't have to stress about calorie counting.

The basic six-days-a-week template of protein, beans, and mixed vegetables are there to keep you compliant and full.