The mechanism works like this..
You eat sugar.. Your blood sugar spikes.. Your skin produces oils (sebum)..
Your pancreas goes to work.. Produces insulin, Your sugar drops, skin stops producing..
When you eat meat (which contains ~30-40% fat), or a great deal of added oils (cooking oil), The Insulin that your body produces becomes significantly less effective.
So, if you eat a typical 'Murica Meal, even if the total carbohydrate quantity is low, your Sugar STAYS HIGH for much longer.. This duration leads to OVERPRODUCTION of skin oils, THUS clogging pores, Feeding bacteria, and Producing Acne..
METHOD 2:
The alternative which also works, is to reduce carbohydrates and eat ALOT of meat, no sugar, no sugar spike, no acne..
HOWEVER, This will give you Heart disease /cancer/ dementia/ Diabetes
Remember That Atkins guy was a crook, The entire time he had heart disease done in by his own bad advice, and he hid it from everyone..