You can find an 'observational' study to promote nearly any point of view. If it's not a properly controlled peer reviewed study it's not worth anyone's time except the shills who got paid to write it up by whatever corporate group commissioned it.
Observational studies have significant problems, as I explicitly pointed out in my comment about the study. However, they have some advantages in that they are a lot easier to do for larger populations over a longer time period.
Both of these are valid scientific techniques, to inform us about what is most likely to be a healthy way to eat. There are, of course, other valid techniques, such as studying immediate metabolic effects of ingesting certain foods, and linking those to known risk factors for a variety of conditions. Science is not a single, infallible technique, it is a set of techniques which taken together are intended to give us the best approximation of the truth, though every method can fail in certain ways.
Diet is an especially difficult topic. Human bodies, human behavior, and differences between different people are quite complex. There are a lot of people who are afraid of diseases of affluence or degenerative diseases that you see coming up more often simply due to our longer lifespan. Lots of people are interested in solving these problems, and I think that a lot of people jump to over-simplifying conclusions on these topics. We've seen this played out in the past; a huge over-emphasis on low-fat diets, that seems to have left us unhealthier than ever. Warnings about dietary cholesterol, when it turns out that the cholesterol in our blood stream has very little correlation to cholesterol consumed.
Every time I hear about some new extreme diet that is supposed to work wonders, I get concerned. Low fat, low sodium, low carb, no carb, paleo, high protein, high fat, vegan, raw, gluten free, dairy free and so on. Most of these things seem to focus on some single source of evil, and claim to offer amazing benefits if you follow them. Most of those benefits don't actually play out; despite the huge push for low-fat diets over the 80s and 90s, obesity continued rising at an alarming rate. Despite the huge popularity of Atkins, "paleo", and other low carb diets over the past decade, it has continued to rise.
People keep searching for a silver bullet, and in diets, like much of life, there is no silver bullet. Eat less, exercise more, eat healthier foods like fruits, vegetables, nuts, and whole grains while reducing the amount of sugars and fats, avoiding too much processed food and so on is not some amazing new diet plan that you'll be able to sell some fancy book about, but it's pretty much the actual advice you need to follow if you want to stay healthier.
Anyhow, I see this over and over again, and then I hear from eager people who want to tell me that low-carb, no fasting, no gluten free, no lactose free diets will help them lose weight, prevent cancer, prevent heart disease, prevent Alzheimers, prevent autism or ADHD, do all of the above and more, and there's no risk, they're so healthy, why would anyone not do this? And then I read the literature, and I find that actually, this new diet has quicker effects in the first six months but is about as effective as the last fad diet was after a year, and actually it does have certain dangers, and so on.
Eat less, exercise more, keep it healthy. Beyond that, don't worry too much, and do everything in moderation. Take all dietary science with a grain of salt, since it's a tough field to study the real, long term effects of (20 year studies are considered to be long term studies, but that's only a fraction of a life, meaning that many real long term effects get very little study). Take industrial food with an even larger grain of salt, as it's more likely optimized for shelf life, profitability, or narrow nutrition claims to be able to put some particular label on it, rather than flavor and health. Don't drink soda; I don't care if it's regular or diet, or whether the sugar is corn syrup or cane sugar. Soda is always extra calories that you don't need, or extra sweetness sans calories that confuses your body. And don't drink venti mochafrappucaremelates, or whatever the hell they're called. Don't eat salty snacks on a regular basis, but don't be afraid to put a pinch of salt in your food to make it taste good. Don't have dessert with every meal, but don't be afraid to have a slice of cake at a birthday party.
Anyhow, rant over. I just get upset when I see people getting religious over some new diet fad, which in 10 years will be the diet that the people selling a new diet fad will be talking about in their "you've been lied to for all of these years. Learn how to really stay healthy and lean!"
> Eat less, exercise more
So eating above one's caloric requirement and a lack of energy are always problems of willpower?
> eat healthier foods
I think everybody can get behind this, it's like thinking of the children.
> fruits, vegetables, nuts, and whole grains while reducing the amount of sugars and fats, avoiding too much processed food
So grains healthy, fat bad? As you don't mention meat that's probably also bad? Well, it's the details that get interesting, what are healthy foods.
It's just that there have been one too many threads of people promoting some particular fad diet idea (gluten is poison! sugar is poison! soylent is the food of the future!) and I'm getting kind of sick of them. I've been hearing these fad diet ideas for years, it's just different things which are claimed to be the poison or different combinations of things or combination of restrictions which are claimed to be the be-all cure.
This thread hasn't been particularly bad, though you were a bit overly pushy about ketogenic diets and dismissive of criticisms of them earlier: "I'm not aware of any scientic data that found adverse consequences. You get a lot of resistace from health professionals because for the last decades what you eat on a ketogenic diet has been blamed for heart diseases or high cholesterol, but there never was scientific evidence to back up those claims."
> So eating above one's caloric requirement and a lack of energy are always problems of willpower?
No, there is not always a problem of lack of willpower. Metabolism plays a role, though diet and behavior play a big role too. There are certain circumstances for which ketogenic diets are appropriate, just like there are certain circumstances for which gluten free diets are appropriate; likewise, just because they are appropriate and effective in certain cases doesn't mean they are appropriate or effective for every case.
I think that for a lot of people, however, the problem is willpower. There are a lot of people who just want an easy excuse or an easy answer, when there really is an easy answer that just takes a bit more willpower.
I do believe that the low-carb, paleo, ketogenic, and likewise diet fads have at least helped combat the harmful emphasis on low-fat above all else. I recall at the height of the low-fat craze finding lots of fat free and low-fat foods that were stuffed with tons of sugar to compensate.
> I think everybody can get behind this, it's like thinking of the children.
No, I don't think everyone can get behind it. There are a lot of people who take the "you can eat whatever you want as long as it's not carbs" idea and eat way too much bacon, pork rinds, and the like.
Fresh fruits and vegetables are healthy. Eating pork rinds instead of a banana because the banana is fairly carb rich and the pork rinds are not is not healthy.
> So grains healthy, fat bad? As you don't mention meat that's probably also bad? Well, it's the details that get interesting, what are healthy foods.
I don't think dividing it into "this entire category of food is healthy, this food is not" is a good way to approach your diet. So no, I'm not claiming "grains healthy, fat bad". Both grains and fats are good for you, in moderation. Likewise meat. All of these things can be bad for you when taken to excess; eating too much meat can give you cancer (and some meats are fattier, leading to the problems with too much fat), too much fat can raise your cholesterol leading to heart disease, too much grains (especially highly refined grains) can lead to spikes in blood glucose and harm your insulin response.
What I'm saying is favor fruits and vegetables over grains, favor whole grains over refined, treat meat as a supplement, flavoring, or occasional treat rather than the central part of every meal, favor unsaturated fats (generally vegetable oils and fish) over saturated fats (generally from other animal sources), and keep refined sugar consumption very low. If you need to lose weight, eat a little less, and try to fill up a little more on things without much caloric value like greens (but don't go spending all of your time eating salads, as they generally come with dressings that consist mostly of fat and sugar, defeating the whole point).
Personally, I follow this by eating meat (of any form, fish, poultry or red meat) only about 3 times a week. I never drink soda (can't stand the stuff now that I'm not used to it any more). I generally use unsalted nuts or fruit as a snack if I need something to tide me over between meals (but don't snack often). I usually buy whole grain bread. But I cook with butter plenty (as well as with olive oil, I love sauteing food in a combination of the two), I put cream in my coffee, I enjoy the occasional juicy steak, I eat a lot of cheese (my one main vice), and I have the occasional dessert.
Now, I don't claim that my diet would work for everyone. That's why I'm not out selling it; it's just what happens to work for me. But I do think that it's good to employ an approach of moderation and avoiding thinking about food in black and white terms, unless there's a very good reason why a food should be completely banned (like if you have celiac disease, a nut allergy, or a moral objection to consuming animals).
