His body mass index went from 28.8, considered overweight, to 24.9, which is normal. He now weighs 174 pounds.
But you might expect other indicators of health would have suffered. Not so.
Haub’s “bad” cholesterol, or LDL, dropped 20 percent and his “good” cholesterol, or HDL, increased by 20 percent. He reduced the level of triglycerides, which are a form of fat, by 39 percent.
That’s from this article on Mark Haub, a nutrition professor who spent two months eating… junk food:
For 10 weeks, Mark Haub, a professor of human nutrition at Kansas State University, ate one of these sugary cakelets every three hours, instead of meals. To add variety in his steady stream of Hostess and Little Debbie snacks, Haub munched on Doritos chips, sugary cereals and Oreos, too.
…Two-thirds of his total intake came from junk food. He also took a multivitamin pill and drank a protein shake daily. And he ate vegetables, typically a can of green beans or three to four celery stalks.
I got that link from this SBM article that debunks a lot of crap folk wisdom on diet (and endorses some of it), for instance:
Avoid chemicals, preservatives, and artificial sugar. This simply an appeal to the naturalistic fallacy. It’s not possible to avoid “chemicals” in your diet; chemicals ARE your diet. The same can be said for preservatives. Salt is a preservative. Added ingredients need to be evaluated on their own merits, not avoided wholesale. The same can be said for artificial sweeteners. Reno demonizes sugar substitutes claiming they “work against you just as much as white sugar does.” Yet here is no persuasive evidence to demonstrate that artificial sweeteners are harmful, or will compromise dietary goals. The same cannot be said for sugar.
Avoid all over-processed, refined foods, especially white flour and sugar. Here’s where we finally get into some specific dietary advice. This is largely reasonable, as heavily processed foods tend to be higher in salt and calories, and may also be less nutritious. There is is very little scientific debate that whole grain products are superior to those that contain mainly white flour, which is missing the most nutritious parts of the grain. There’s also good evidence to suggest many people obtain an excessive number of calories from sugar, and from refined carbohydrates in general. However, advising that all white flour and sugar be avoided is very difficult, and there’s no reason they cannot be consumed in moderation. What matters is the overall caloric balance.
Depend on fresh fruits and vegetables for fiber, vitamins, and enzymes. Fruits and vegetables are good sources of nutrients, fiber and vitamins. but so are other foods, such as grains. Insisting on “fresh” produce is unnecessarily restrictive, as frozen or canned versions can offer the same nutritional benefits. Enzymes are large proteins that act as catalysts for biochemical reactions throughout the body – but our body produces what we need, and digests the ones we consume.
There’s more at the link.
Not Unreasonable 
I’m not so keen on the clean food diet, but you’re missing on a couple points. When they say avoid chemicals, they are suggesting you read the ingredient lists on the food and if it includes chemical names, rather than names of foods, avoid it.
Also your claim that refined flour is missing the most nutritious part of the grain is not correct. It’s missing the fiber, which is not nutritious. It does help your digestion and is considered an important and healthy contribution to everyone’s diet, but provides no calories or nutrition. Also most processed while flour is “enriched” with micronutrients (vitamins). It’s still bad for you and whole grain is better but no-grain is better still.