> I'm genuinely curious as to what you're getting at. When you say "excess of carbohydrates", are you referring specifically to processed foods or refined sugars?
Long story short: many diseases are insulin linked. Insulin spikes highest by repeatedly eating carbohydrates throughout the day. Fiber decreases those spikes somewhat, but still doesn't compare at all to a fat-based diet or protein-based diet. There are ways to cope with an excess in carbohydrates (heavy exercise is one, fasting is another), but there is no way to cope with a lack of fat. Additionally, mitigation strategies can cause their own problems (many joggers, especially vegetarian and vegan ones, start developing iron deficiencies). The whole "it is just processed sugar" thing is just the tip of the iceberg.
>I highly doubt nuts and seeds were.
Put in perspective: foraging for nuts and seeds is a lot more difficult and intensive than hunting a giant mammal. Plus, the former is a lot more seasonal than the latter.
>But that doesn't really matter if we're talking about what we can do today.
It does. Human evolution and mutation is slow. By looking at what our primary diet was up until recently, we can understand the macronutritional and micronutritional needs of our body and how a vegetarian/vegan diet may or may not influence that.
>Things like avocados, olives, coconuts, and the above-mentioned large categories of nuts and seeds, are readily available for most people making these sorts of arguments. Plus, if you're vegetarian and not vegan, then you have access to cheese, yogurt, milk. It's easy to eat high fat and low carb while avoiding meat, so the argument for eating meat to be healthy on these grounds seems quite weak to me.
The main thing currently under scrutiny is the bioavailability and toxins (for lack of better term) of plant-based foods compared to meat. Turns out a lot of plants don't want to be eaten, and when you can't move, you start developing ways to protect yourself without requiring locomotion. Not only are various of these toxins decreasing bioavailability (zinc is a big one, eating beans with oysters is a terrible way to decrease bioavaialability of zinc), these toxins are actively causing harm and inflammation, whereas a meat-based diet is seen as the "ultimate restriction diet". Avocados, coconuts, olives and nuts stand out here, being more fat heavy, but as most of the population does not have a history with these compared to animal products, it is difficult to say its all good. Beyond that, it is very difficult to get all your minerals and vitamins just on those alone, which isn't the case for meat and seafood, which results in either tapping into the remainder of the veggies and fruit, or tapping into animal products.
Obviously, the argument is more than macros. If macros were all that mattered, you could just stuff your face with whey protein and vegetable oil and call it a day. The argument in favor of meat is a lot more nuanced and without that nuance, will be ruthlessly picked apart by the pro-vegan gang who tend to be a lot more zealous than their carnivorous counterparts (the carnivores have nothing to lose if vegan diets prove to be better, they are already on the moral low). To explain this in its entirety would take far more than a HN comment.
What's concerning is just how much meat-eaters have to play the defense. We don't know that much about vegan and vegetarian diets compared to an ancestry and entire tribes of carnivores. We put forward theoretical models devoid of animal products, using obscure plants to fill in some deficiency, but never test whether it will work on the larger scale. The ecology argument is thrown about as if people don't understand how carbon cycles work. It's humans going vegetarian and vegan which deviates from the status quo, not the other way around. We should be questioning the long term (multi-generational) effects of it as long as we haven't put hoards of people on a vegan or vegetarian diet that didn't include some shady 10 ingredient meat-replacement containing added sugar. We should also be questioning our current understanding of the "cows bad beans good" narrative, and what truly is the cause of the problem (human greed).