system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why was I taught all about "The food pyramid" during school but later in life I found out it was apparently all wrong..?
gpt
The fact is our bodies are very, very complicated and the science has been dead wrong over and over regarding them, especially in regards to nutrition. 

Up until about 10 years ago it was assumed that fat makes you fat and cholesterol intake clogs your arteries. 

As it turns out, the only biological signal to the liver to store fat is sugars/carbohydrates. Fat on the other hand, in the absence of much sugar, is used as fuel (particularly for the brain) and discarded. 

Cholesterol on its own is not bad, it's a required nutrient in fact.

During the low/no fat diet fads of the 80s and 90s people thought they could gorge themselves on low/no fat chips and cookies and lose weight. How wrong we were on something so simple to test. 

Science has become religious for some  (especially around these parts) and they've misunderstood it to be gospel rather than "this is what we think we understand about X at this point in time". Because of this dogmatic thinking, the food pyramid many of us followed and became overweight following was making us all into sugar/carb addicts or worse, diabetics, and nobody wanted to stand up against the scientific authorities  (particularly the USDA)