If you can't, or won't, it is not a scientific field.
Unfortunately, like most fields it’s the junk you read about because rigor is difficult/expensive and therefore less common than BS. Just look at say fusion research and all it’s seriously flawed experiments.
Sure, human biology is (hundreds of) orders of magnitude more complicated than say going to the moon.
But at this point in 2024 we “know” a lot more about physics than we do about nutrition.
And maybe that’s because physicists, when faced with contradictory data, keep digging until they figure out the basics once and for all.
The problem is that the public doesn't want to hear it, so the media keeps running articles that make it simple like "nobody knows anything". Which is just plain false.
About the only things I see as generally accepted are to eat a varied diet (whatever that means), keep total consumed caloric content near the amount expended, eat at least the RDA of micronutrients, and drink enough water to avoid overt dehydration.
But generally - yes, afaik there's mostly a consensus that total caloric intake is the driver of amount of adiposity, that maintaining a 10%-20% body fat percentage (for men) is optimal for long term health, that most diets are close from a health and fat-loss perspective - meaning, amount of adiposity is the main driver of long-term bad health, especially as compared to individual ingredients. There are some things that are known to be specifically problematic, e.g. trans-fats, at any amounts. And there are healthier and less healthy foods, some of which we know - but total caloric intake is the only driver of body composition, and a bigger driver of body health.
Most of this is basic - probably because, as I said, I'm not a nutrition scientist myself so only understand the basics myself.
That said, a large part of the population doesn't even understand these basics either, preferring to constantly talk about and argue about specific diets, keto vs. vegan vs. whatever. And science mostly has that question covered, as far as we can tell right now.
For a more in-depth take on this from someone who actually is an expert, I recommend videos by Mike Israetel:
https://www.youtube.com/watch?v=7FM9VAH_EXw&list=PLyqKj7LwU2...
There is a long list of things that cannot be synthesized by people and must be consumed. (Elements like Potassium as well as specific nutrients like Vitamin C and Thiamine being well known.) There’s a longer list of things than can be synthesized but should largely be consumed ex:
Linoleic acid (LA), an omega-6 fatty acid, and α-linolenic acid (ALA), an omega-3 fatty acid, are considered essential fatty acids because they cannot be synthesized by humans.
The long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can be synthesized from ALA, but due to low conversion efficiency, it is recommended to consume foods rich in EPA and DHA.
There’s also a lot of basic facts that get complicated when you dig into them. For example calories produced by burning foods isn’t 1:1 with the calories available to people. Cellulose for example burns but is effectively indigestible. One way to investigate this is to have some eat something and then burn their poop, followed by many studies that do so for various reasons.
There’s also a lot of nutrition science that straddles the line with medicine. Thus there exists many specialized diets for various conditions etc.
I also tend to think there’s real nutritional science but it’s being drowned out by all the snake oil.
It reminds me of the studies they've done in Canada and the US about how natives (American Indians) die a lot of the time in the ER because they're immediately written off as alcoholics or drug-addicts, and so their complaints are evaluated through the lens of "this person just wants opiates."
This is underscored by frequently cited articles, like: "The Unreasonable Effectiveness of Mathematics in the Natural Sciences", in which math is treated as separate, but intimately related, to natural philosophy.
I think you can do math without science, but you can't do science without math.
While a scientific or engineering background might demonstrate capability to understand another scientific field, that doesn’t replace the near decade of education people in that field have.
A dedicated physicist who self-taught medicine would allow hoofs to be zebras, not horses, some % of the time.
Doctors need practice in the hospital and do an excruciating amount of rounds surrounded by senior experts.
Nutritionists? No.
Given a nutritionist who has studied the books and gotten a degree and a physicist who has studied the books and hasn't gotten the degree I would be hard pressed to choose the nutritionist
I would absolutely trust a physicist (who has done actual empirical lab work) who has deeply studied a problem in the nutrition space over someone conventionally trained in nutrition.
You may be stunned to see how little numerical sense so many in the medical field have. And as someone who grows medicinal plants and follows that literature closely, I read tons of papers in that space. It is full of experimental design flaws and dubious correlations.
I have worked on a medical device that went through clinical trials.
Cause from where I'm sitting, nutritional scientists do plenty of real science - studying a very complex problem that poses a lot of challenges to experiments, and still coming up with a lot of great results that teach us tons about nutrition.
Most people that criticize the field do so because they read a bunch of articles. Or because they're in the world of hard sciences, and are simply arrogant enough to think they know better than everyone else, even in fields they've never studied.
If you have a real scientific background and real engineering background you are way more likely to do a proper job.
It frustrates me that people think nutritional "science" is a serious scientific field. And that the "nutritional scientist" is somehow better equipped - they have barely done any real science a single day in their life.