Comparison of Diets

There are a lot of diets that are very similar.  I think you could have a number of columns that you could put an X in to describe a feature.

Features
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Restrict salt?
Allow olive oil?
Allow vegetable oil?
Emphasize low-fat or nonfat dairy?
Allow cheese?
Include lean meat?
Allow beans?
Emphasize starch (rice and potatoes)
Limit calories to 1200 (or 1500) per day?
Encourage fiber in the form of wheat germ or flax seed?
Limits bread?
Limits fruit?
Limits sugar?
(more to follow)

List of Diets to review
===============
Vegan
Vegetarian
flexitarian
Daniel Plan
Whole30
Dash (also Dash/Med  and Dash/Weight loss)
Mediterranean
Dukan diet
(more to follow)

I will review one per post and try to give each a fair shake.

Dukan Diet
The first one on the list is the Dukan Diet, because it is ranked last on the list of the US News and World Report Diets.  The first on their list is the Mediterranean Diet.  My thesis is that they are actually not that different.

Home page: https://www.dukandiet.com/

My impression of the Dukan Diet is that it is similar to the keto diet except it limits fat.  It allows for unlimited lean protein.  It avoids fat, for example: non-fat dairy only; no skin on chicken; only limited salad dressing.  Phase One (Attack) doesn't allow any vegetables.  It requires oat bran, presumably for the fiber.  Phase Two (Cruise) allows vegetables on alternate days, but doesn't allow any bread.

The distinguishing characteristic of a Dukan diet is the emphasize on lean meat avoiding fat.

My comparison to the other diets is based on the Cruise phase days where vegetables are allowed:
restricts salt?  no
allows olive or vegetable oil?  no (except for 1 teaspoon daily for salad dressing)
emphasizes low-fat or no-fat dairy?  yes
allows cheese?  no (except for no-fat cottage cheese)
Include lean meat? yes 
Allow beans? no, not on the Cruise phase
Emphasize starch (rice and potatoes)?  no
Limit calories to 1200 (or 1500) per day? no, this has no calories counting as long as the plan is followed
Encourage fiber in the form of wheat germ or flax seed? yes
Limits bread? yes, bread not allowed until the consolidation phase
Limits fruit? yes, fruit not allowed until consolidation phase
Limits sugar? yes, sugar not allowed.  Sugar substitutes are

What are the criticisms of the Dukan diet?
It is pricey.  The food (only lean meat and non-fat dairy) is expensive.  Plus you really should buy the book and get coaching at $29.95 per month.
No clinical trials.  This is probably the biggest concern of nutritionists.
Excess protein.  Too much protein with limited carbs can force the body to do gluconeogenesis, where the protein is basically treated as a carb and turned into glucose.  There is also a concern about kidney stones for some people.
Strict rules.  Especially on the first two phases.  (But I think all diets have rules by definition).

Why is it ranked so low?  Unknown, but probably because there haven't been any clinical trials, and because on the first phase it avoids vegetables.

I think the proper comparison is the Cruise phase vegetable days and it is actually similar to other plans on those days.

Update:
What kind of meat is allowed on the Dukan diet?  (This is my understanding based on what I have read).  Fast food hamburgers are not allowed because they are not high-quality and have too much fat.  Only get  the lowest percentage of fat, which is 93% lean/7% fat.  These will be more expensive.  Steak is allowed but trim the visible fat. Also get lean turkey or ham lunch meat.  No bacon, except for turkey bacon.
Are french fries allowed?  No, the Dukan diet tries to limit fat intake.
Are nuts allowed?  No, not on the cruise phase because they are too high in fat.
Is coffee allowed?  yes