I think most of us forget that the role of food is actually to be fuel for the body. The food industry is just trying to confuse us and they use all kind of tricks to make us buy their products. The reality is that we have a very good idea what is the right fuel for us. For most of the human history we ate simple fresh foods and our body evolved to function the best with this type of fuel. The best is to eat foods that are in season with maybe the one exception being the vegetables.
The food industry confused us to such a degree that common sense does not apply to food anymore. For example, in diabetes (which affects 1 in 10 adults in US) carbohydrates increase blood glucose. The common sense would be to avoid carbohydrates in diet, but the food industry convinced everybody (including medical professionals) that we need just to set some arbitrary limits for carbohydrate intake in diabetes. Imagine that you put diesel into your gas engine car and then you go to your mechanic. The mechanic is going to fix your car first time. But you put diesel again and again. By the third or forth time the mechanic will just give up. Also the mechanic is never going to tell you just to just add less diesel into your gas car. In diabetes we lost our common sense and the medical professionals just tell people to use the wrong fuel (carbohydrates) but relatively not too much of it. And then the medical professionals just keep patching the engines (various organs) damaged by uncontrolled diabetes day after day…
One of the organs that is greatly affected by the wrong fuel is the liver. Our livers are the first stop for the digested ingredients in the food. According to the paper by Younossi Z et. al. Hepatology. 2019: “Over the past 2 decades, nonalcoholic fatty liver disease (NAFLD) has grown from a relatively unknown disease to the most common cause of chronic liver disease in the world. In fact, 25% of the world's population is currently thought to have NAFLD. Nonalcoholic steatohepatitis (NASH) is the subtype of NAFLD that can progress to cirrhosis, hepatocellular carcinoma (HCC), and death.”
Part of the problem in US is that we never had a unitary food culture. This is a theory described in the book “The omnivore’s dilemma” by Michael Pollan. According to Michael Pollan: “So violent a change in a culture’s eating habits is surely the sign of a national eating disorder. Certainly it would never have happened in a culture in possession of deeply rooted traditions surrounding food and eating. But then, such a culture would not feel the need for its most august legislative body to ever deliberate the nation’s “dietary goals”—or, for that matter, to wage political battle every few years over the precise design of an official government graphic called the “food pyramid.””
Eating simple fresh foods can prevent a lot of diseases. But once you got a disease a great effort needs to be done to reverse the disease. The sickest somebody is the biggest the effort required. For example, in diabetes type 2 related to obesity things have been going badly for so many years that it will take years to reverse it with a very strict dietary approach. And maybe the metabolism will never be back to healthy level in people with long standing diabetes. But at least we have to try.