Chung has more than 5,000 friends on his Facebook page, where he frequently posts scripture and has shared photos of his meals on a scale.
In one picture, his lunch--a sandwich, chips and a cookie-- weighed in at 15 1/8 ounces on a food scale, half of his daily allotment.
But Ayoob worries adherents of the diet, especially children, are missing out on nutrients and are being sent a potentially detrimental message that being full is equated with guilt.
"The bottom line is that you don't get enough nutrition," he said. "I make recommendations based on sound science and these are not."