I read "The 150 Healthiest Foods on Earth" (Jonny Bowden) recently and took from it this extremely condensed diet advice: "Avoid grains and industrial processing." Grains have near-zero nutrition, and industrial processing is the source of a lot of questionable practices.
On this diet, which I've followed just a few weeks, I cheat all the time, but I feel and perform better in ways that I can quantify at the gym: more strength, better endurance. Noticeable improvements every time I've gone, so far.
This is the annoying thing about diet/nutrition advice, and why "The Hacker Diet" is really appealing to me, even if it's a little simplistic -- it's at least logically consistent and has some rationale behind it, even if it's a flawed one.
Most diet advice is vague and full of generalizations and never backed up. It makes sense, but you hear often opposing viewpoints made in the same hand-wavy fashion. For instance:
Okay, why avoid grains? Are some grains worse than others, or are they all magically bad? Either way, why, and what evidence supports it? Does this apply to any carbohydrate, or just strictly grains? What's wrong with industrial processing, and is there evidence to prove it? Does it apply to everything that could possibly be considered industrial processing, or just certain types of industrial processing that are particularly bad? Is it possible to make up for whatever negative effects it (anything one is advised not to eat) has, and does it apply to 100% of people, or a set of people that you make a set of assumptions about?
I'm not attacking your viewpoint specifically -- I think you're most likely right -- but this is just why I have a hard time believing most diet advice. It's always so wishy washy, and it always brings up more questions.
Another example: advice around drinking soda. There are many types of sweeteners used in diet sodas, and lots of studies done on their effects on humans and other mammals -- none particularly damning. But no one giving nutrition advice will say "avoid ingredient X because Y", they'll say "avoid (vague category of food which may or may not contain ingredient X)". And then someone else will come along and say the opposite. And then there's always some link to some study done in the 1940's that's since been discredited or something.
It is like a safe harbor provision. If you exclude processed foods and grains, then you are in a relatively safe place food-wise, though not perfectly safe of course.
If you do eat processed foods, then you take your chances or you must spend a lot of time educating yourself about various ingredients and the studies about them.
carbohydrates are all nothing but sugar, they do nothing for you. Grains are particularly bad because they not only don't provide anything but sugar but they also prevent the absorption of minerals(in the link he explicitly calls out oat meal but others do it as well). Studies show that cutting out grain(note some grains are ok mostly freshly processed grains are bad. Sour dough is OK) will make your teeth immune to tooth decay and any cavities you have will heal themselves.
It's going to be lower quality than unprocessed fresh food, for several reasons:
1) Food spends longer between harvest and mouth, so any nutrients that are lost over time will be reduced in the final product.
2) Food crops are of varying quality, and the highest quality will go directly to places people will see it (e.g. tomatoes in the supermarket vegetable section) and the lower quality (less ripe, overripe, blemished, part squished or bruised) will go to the industrial processing where it ends up not being noticable (e.g. XYZ in tomato sauce).
3) There's a lot of scope for badness to be included in processed foods. When dealing with trailer loads at a time, detailed checks are impractical so contaminants become more possible. Food processing is factory work which is generally low skilled, low paid and long hours, so there's more room for things like poorly cleaned machinery, accidental contamination by people, gross fooling around, a nod and a wink and sod the overbearing health and hygiene rules when workload is high.
4) Labelling laws in some countries only require ingredients of more than X amount to be included, so there is room for contents that you don't know about and therefore can't choose whether or not to eat.
5) Industrial processing is full of bizarre things. Who eats cotton? Nobody. So how come it's OK to put cottonseed oil in food? Why is nickel used as a catalyst in the making of margarine? Nobody uses nickel as an ingredient or as a material for cooking utensils.
6) It exists to make money, not to make you healthy. Food processing is better if it takes cheaper ingredients and makes a more expensive desirable product. They are hacking your perceptions, studying flavouring and colouring and mouth-feel and so on, to make something look and taste nicer, while not actually doing you more good (or even, less harm).
and is there evidence to prove it?
I think this comes under the side of "prove God doesn't exist". Humans lived for a long time without mass food processing, and now we have it it's accepted as fine and the suggestion is that we have to prove that it's bad. Surely the default state is to be without food processing, and supporters should have to prove why it's good? (Apart from the fact that it makes lots of money, that is).
Is it possible to make up for whatever negative effects it (anything one is advised not to eat) has
Who knows? Ask yourself why some 70 year olds are out hill walking, travelling, working, are healthy-albeit-old and some are demented, plagued with ill health, bedridden, seriously forgetful, suffering arthritis, heart disease, loss of balance, etc.
On this diet, which I've followed just a few weeks, I cheat all the time, but I feel and perform better in ways that I can quantify at the gym: more strength, better endurance. Noticeable improvements every time I've gone, so far.