Among them are the fact that the so-called "food pyramid" was never created by scientific inquiry -- rather, it was a combination of agribusiness influence and outright government corruption.
The amount of brainwashing that goes on in our society today in this regard is hideous and infests virtually everyone. We "learn" from an early age that fats, especially animal fats, are bad for us while all that is easy and cheap to make, especially cereals, breads and similar, are good. That "margarine" and other "lighter" (but engineered) oils are good, what they displace (e.g. butter) is bad. That the word "light" on a label means that it's better for you than the same product without the "light."
So what has following this advice gotten us? Record obesity and Type II diabetes, along with heart attacks, strokes and massive and outrageous morbidity.
You government has been literally killing you.
The truth? God knows better than man. Man corrupts any time it's profitable, and boy is it profitable when it comes to this sort of thing.
What do you want to eat? What you ate before your government was around -- or any government was around.
That was not engineered food.
It was foods such as eggs, meats, fishes and unprocessed plants, subject only to being cooked.
Fat in food does not make you fat. Carbohydrates, especially easily-digested carbohydrates, make you fat because they are released quickly in the digestive system and when your body's glycogen reserves, which are modest in size, are filled the body must convert the remaining carbohydrate to fat and store it in order to avoid driving your blood sugar through the roof.
Worse, the insulin response that is necessary to this process (and to maintenance of your blood sugar level within the normal range) results in you feeling hungry when the process of carbohydrate-to-fat conversion nears completion. The hunger response is not linked to your glycogen reserve level, something that anyone who eats low-carb (and thus has low glycogen reserves all the time) can tell you is a fact.
Unfortunately if you eat when your glycogen stores are high you will immediately store all of what you take in to fat rather than using it for energy.
Now add to this how one makes a particular thing (e.g. salad dressing, etc) "light" -- you remove fats and replace them with carbs. The "light" version will actually make you hungrier and thus fatter, exactly the opposite of what you would expect!
The other problem is that everyone has claimed that saturated fats are "unhealthy" and the opposite are "good." But there is no scientific basis for this; "observational" studies are worse than useless as they identify "things" that are simply not true because they fail to isolate the causative factors. For example, you could say by observational study that water causes cancer because everyone who has cancer has consumed water. This would obviously be nonsense, but it is exactly what observational "studies" offer up all the time!
What's worse is that the other half of the claim on fats in the diet, that polyunsaturated fats are "healthy" (while the other kind are bad) may be literally killing you. Most of those oils are very high in Omega-6 fatty acids -- indeed, processed seed and vegetable oils are pretty-much where it all comes from in our diet, and none of that is natural; without industrial processing these "foods" would not exist. The really bad news is that systemic inflammation is caused by too much Omega-6 in the body, and the body's response to inflammation is to try to "fix it" under the assumption that the reason for the inflammation is some sort of intruder that doesn't belong in the body at all. That's great if the cause of the inflammation is a thorn you stepped on that is causing an infection. It will kill you if the inflammation is in your coronary arteries because you're eating crap that was engineered by man and our body responds to it as if we were eating a poison!
Finally, cholesterol. There are literal billions of dollars made every year prescribing statins to "lower" cholesterol. The problem is that cholesterol is necessary for life, that it is synthesized by the body and that most forms of it in the body are either benign or helpful. Worse is that the standard three-panel test for cholesterol (LDL, HDL and Triglycerides) is worthless because the triglyceride number is not directly measured and only one subtype of LDL is harmful in the body! The only meaningful test is one that is much more expensive and thus rarely used. At the same time statins have a litany of side effects that are in and of themselves dangerous, including cognitive impairment and muscle damage, some of which can be permanent.
As an aside counting calories is virtually guaranteed to fail. The reason is that 3,000 calories are, more or less, one pound of body mass. That is, 30,000 calories are 10lbs. If you're off by as little as 100 calories a day you will gain or lose 10lbs a year. In 10 years that's 100 lbs and that's enough excess to call anyone fat.
100 calories is about the caloric content of one banana, less than one 12oz can of sugared soda (that's ~140 calories) or ten potato chips. Can you possibly count your caloric intake in a day closely enough to be less than 100 calories "off"? No.
But your body can do this on its own if you don't destroy its hunger/satiation balance. Just as a normal human body has one teaspoon of sugar circulating in the blood stream at any given time (yes, just one teaspoon), an amount impossible to accurately regulate manually yet one that in a healthy person is automatically maintained the desire to eat or not is also automatically regulated and will maintain caloric balance on its own if you don't destroy it.
Stop listening to the crooks that have less interest in your health and more interest in selling you cheap engineered products that are very profitable for them even though they are in fact slow poisons.
The simple way of looking at this is that if whatever you're about to stick in the pie hole couldn't exist without modern chemistry you're at risk of consuming something manufactured without regard to your health and safety, but rather only with regard to someone's profit.
Am I talking out my ass? Well, you tell me -- on the left is what I was eating the so-called "food pyramid." On the right is what I have looked like for the last two years -- roughly 60lbs lighter.
I pay no particular concern to trying to "meter" calories yet my body mass has been +/- 5lbs for the last two years with zero excursions beyond that boundary.
That means that I have managed to maintain my caloric intake to within a tolerance of 50 calories a day (at the outside) and in fact it's probably closer to 20 calories -- or an amount that sums to roughly two potato chips or a couple of broccoli crowns on a daily basis.
That's obviously impossible by actually trying to count intake, as to be that accurate I'd have to have a scale with me at all times, eat only the prescribed amounts and have effectively zero error, no "snacks" or other impulse consumption and similar. Outside of a laboratory where one is confined 24x7 that's impossible.
You can choose to not be a fat bastard, no matter where you are now.
The way you choose isn't a function of how much you exercise, although you might find, as I have, that exercise is actually enjoyable, especially when you're not 50+ lbs overweight.
Your body mass is a function of what you eat and whether you listen to those who are effectively trying to slowly poison you for profit -- or not.