I dont want to talk in excessive depth about it because i'm not an expert, but it's like...the agriculture textbooks go into detail about what the nutrients do for the body and how they are broken down, in the animal agriculture class talking primarily about how to feed your animals, the plant agriculture class talking about why certain crops are grown and how the agriculture system has to meet human needs.
The animal agriculture class was the first time I experienced each macronutrient (fats, proteins, carbohydrates) being discussed in depth from the point of view of being needs that MUST be met, rather than things it's "okay" to eat "in moderation."
My college health class actually used the word "macronutrient," but it still mostly described fats and carbohydrates in terms of their calorie content and didn't go into the same amount of depth about them.
My animal agriculture class on the other hand, was the first time I'd been taught in a class that the amount of nutrition absorbed from eating food varies depending on genetics, environmental factors, what the digestive system is accustomed to processing and what it was conditioned to process during development, and mechanical aspects of the digestion process like how much it is broken down by chewing (!!). Of course it was discussing these things from the point of view of like, cows, but it was really striking to me that I'd never been taught about human digestion from this point of view, where digestion is a complex process that can be affected by various biological and environmental factors.
At the beginning of the class we did a lab where we went over feedstuff analysis, and this was the first time I'd learned about where the numbers in nutrition labels come from, the kind of tests that are done to break food down to its components.
The class discussed how the digestibility of food was analyzed by testing the food, feeding animals the food, collecting the feces, and doing the same tests on the fecal matter to determine how much of the starting nutritional content was literally just going out the other end.
This raised a lot of questions for me: I don't think Pop-Tarts are analyzed by confining a human volunteer to a small room and feeding them only Pop-Tarts, then doing lab tests on their poop. Does that mean we know even less about feeding humans than we do animals? At any rate, nutrition labels would have to be rough estimates to begin with, and then accounting for the variability in the way bodies process food, it's even less descriptive.
Now i'm in plant agriculture, and I'm learning about the different types of proteins and fats and what plants and/or animals they come from. There are different types of protein with different sources. There are...nine? I think? different amino acids that have to be consumed in the diet, and different foods contain different ones?? The reason combinations of grains and legumes are so common as staple diets throughout the world, is that this is closest to being nutritionally complete for humans???
And also protein supplements are mostly useless unless you're an Olympian or something, because the body doesn't have a way to store protein for later. If you eat protein and your body doesn't have an immediate use for it, it just gets taken apart in your liver and you pee it out. Sports greatly increase your need for energy far more than they increase your need for protein, but everyone thinks you should eat a ton of protein as an athlete and that carbohydrates are unhealthy.
I learned from the same chapter WHY fiber is important to help digestion (having texture to the stuff in your gut stimulates peristalsis which is the muscular movements that push things along).
I feel really weird and resentful about health textbooks and classes now, because it feels like they didn't want us to have the facts on how our bodies work, and instead just taught us to see certain foods as "good" or "bad," as though it was more important to be afraid of "unhealthy" food than to understand why food is needed. Health classes barely teach why food is needed.
Like, vegetables are seen as the quintessential "healthy" food, but what is traditionally seen as "vegetables" are mainly important because they provide micronutrients, fiber, and water (the water content in food is actually a big deal). There's a reason they aren't staple foods. You need carbohydrates and fats to live. Period.
I say "what is traditionally seen as vegetables" because it's an incoherent category nutritionally. Beans, sweet potatoes, and spinach are doing very different things for your body. Are beans even a vegetable? Clearly "comes from a plant" isn't the main criteria since grains, nuts, and fruits aren't considered vegetables.
So like, the "myplate" graphic (and the "food pyramid" that came before it)? Total bullshit basically.
It's really frustrating how writings on healthy eating assume you are probably already eating too much or are at risk of overeating. I learned very young about the harms of being "overweight" and eating too much of a certain nutrient. But I just realized from my reading in the plant agriculture class that I had never read a resource that teaches in the same detail about the harms of undernutrition.
It's so easy to fail to get the nutrients you need, holy shit. Particularly protein, because it isn't one thing, it's a bunch of different types of molecule pieces that are found in varying amounts in different foods. People who eat animal products or soy don't have to worry about it very much, since they are essentially complete in terms of protein, but if you are a vegan who doesn't/can't eat soy as a staple, you HAVE to be careful to eat a variety of foods that complement each other in terms of what they're lacking. There's something called the PDCAAS that rates each food by the amino acids they contain, but generally the best idea is to eat a bunch of grains and legumes.
I'm not saying that people can be "scared straight" out of developing eating disorders. But I am saying that young people can benefit from being exposed to scary information when they have the power to possibly encounter situations where that information is applicable. And the horrifying realization of what starvation is and does is such an information.
My plant agriculture text explained that carbohydrates and fats are the basic sources of energy under normal circumstances, and that it takes around 1,600 kcal per day to run your internal organs. Protein is only used for energy in unusual circumstances. When fat reserves are exhausted and there isn't any food, the body starts breaking down proteins for calories—and the first ones to go are the ones that are already all throughout the bloodstream, found in YOUR ANTIBODIES. That's right, when you run out of fat to burn off, your body starts EATING ITS OWN IMMUNE SYSTEM.
The plant agriculture book also says that digestion and energy needs vary from person to person, like literally when different people eat the same meal their blood sugar rises different amounts, and that how the body decides to store energy or use energy stores is determined by complicated feedback loops controlled by hormones. Meanwhile the average person thinks that it's a matter of "eat too much = get fat and unhealthy, eat less = lose weight and be healthier" and even the college health class I took used more or less this model.
Like people are walking around with this completely wrong idea of how their bodies work and making AWFUL decisions based upon it because the resources they have to educate them think it's more important to...make people afraid of food? I don't think it's even common knowledge that the body burns most of the calories you consume just from existing. I want to chew concrete.
Why don't we teach everyone in school why staple foods are staple foods?! Not even getting into people who are so deep into eating disorders they think carrots have too much sugar, it's so normal to do things like "cut out bread" or "cut out carbs" (????!??!) and to perceive hunger as an innately untrustworthy thing, when genuine success at dieting like this is a great way to Corn On The Kill Yourself.
I'm just kind of reeling right now at how much research and monitoring it would take to safely diet in the ways people constantly attempt to diet with NO research NO supervision NO medical testing, 100% believing that they are doing something good for their health.
If people aren't taught what a macronutrient is and why you will die without it, they will think celery sticks are a "healthy" substitute for a chocolate chip cookie, and then not understand why they feel like shit.
Also... this is slightly different, but it's connected to the problem of "people not understanding what food does to the body". In the animal agriculture class, it was surprising to me how in livestock animals, things like muscle and fat composition are strongly genetically determined. All the modern breeds of cattle, pigs, chickens, etc. used in corporate farming have been bred to be very lean and have very little fat while having huge amounts of muscle tissue, because that's what the modern consumer wants in meat.
With pigs, a lot of older heritage pig breeds were bred to store most of what they ate as fat, because pigs were used to change food waste into lard that could be added to cooking for flavor and calories. And most of these breeds either went extinct or dwindled severely to be replaced by "meat" breed pigs that don't put on very much fat at all.
With humans, "everyone knows" that the amount of fat and muscle in your body comes from what you eat and how much you exercise. But a feedlot-finished beef cow that spends the last several months of its life doing nothing but gorging itself on carbohydrates will stay lean and put on muscle because it's genetically predisposed to.
It violates common sense and yet a multi-billion-dollar industry revolves around cramming animals into a small area without much room to do anything, feeding the animals whatever crap has the most calories in it, and ending up with a lean, muscular carcass.
