Dr Atkins was rather cautious about the fat fast - he suggested first checking that metabolic resistance was not as a result of a sluggish thyroid - he suggested testing the body temperature before getting out of bed with a clinical thermometer, and if the average of several days testing was under 97 then it was a certain indication of thyroid problems which needed addressing.
Next he suggested going 'hard induction' - just almost carbless foods, meat fish eggs cheese.
He argues against fasting as a means to lose weight as it usually ends up with a reduced lean body mass after the fast, and a rapid regaining of weight as fat in the following days. Some of the few small trials done using low carb back in his day showed that low carb high fat resulted in a greater loss of fat than fasting, or low calorie diets which were still high in carbs - so he was backed up in his warnings on low intake of foods being potentially bad news.
One of the small meals suggested involved half an avocado, meat and mayonnaise, and another was egg and pork rinds - another was something with caviar.
