This comment sums up an alternative to the Fuhrman approach that is more fat heavy:
" ... based on what I've read and the lectures I've listened to over the last year, I'd say that the low carb, high (healthy) fat, moderate protein (LCHF) diet works for more people with type 2 diabetes than Fuhrman's diet, BUT his diet DOES work well for type 2 diabetics too. Which diet works best for you likely will be influenced by what your ancestors ate. If you enjoy eating grass-fed, pastured meat, free range poultry and eggs, and wild seafood, try the LCHF diet first. If you prefer a whole food, plant-based diet (vegan or vegetarian) try Fuhrman's diet first. Of all the books written on the low carb diet, Mark Hyman's book, The Blood Sugar Solution, is probably the best because it goes into greater detail on all aspects of a healthy diet, not just low carb. ..."
Basically, the "Fat makes you fat" meme (which led to eating lots of refined carbs) has been terrible for our health! Our brains are mostly fat. Healthy fats are an important part of any diet, although we can argue about the best sources of them.
The "Banting diet" (later variant is the Dukan diet) builds on that protein/fat alternative -- but a problem with that approach healthwise is that too much protein and meat from badly raised animals can cause other health issues in the long-term (as well as ethical issues). Of course, it still may be better to get rid of diabetes first anyway you can and then worry about preventing cancer later when you feel better...
I also think Fuhrman is probably low on his iodine and vitamin D recommendations. And his general advice may not be a good match some few people with specific needs from genetics or microbiomes.
In general, Fuhrman's history as a world-class athlete in training may also bias him towards expecting so much that some people give up entirely (so, there is social / psychological aspect of all this that is somehow missed -- perhaps intentionally) whereas they may have done better with a lesser approach. I also agree it is very easy to backslide when only one family member makes the change and is constantly confronted with other people in their space with SAD eating habits.
Another interesting discussion with a specific disagreement with Fuhrman vs. McDougall even within broad agreement:
"The similarities between these 2 doctors and their dietary approaches are far greater than their differences."