I'd say modern grains and "vegetable oil" are probably the biggest issues... heritage grains in moderation are more okay. We take in a lot of refined grains and sugars. And cook everything in oils people wouldn't recognize as food a couple hundred years ago, let alone trans fats.
That combined with a huge uptick in constantly eating all the time, sugary drinks, etc... eating 6-8 times a day. Most people can get away with 1-2 meals a day and a small snack or coffee outside those main meal(s). Longer fasting has historically been involuntary and/or religious, has other benefits that should be included pretty regularly as well.
I think animal proteins and fats are good to keep, even just eggs, butter and fish. There's a lot of nutrition in egg yolks, kidney and/or liver meat and it isn't the same from vegetable sources. Animal protein is also a bit different in terms of absorption than vegetable as well. It's not hard for people to get 100-150g of appropriate protein a day on average either and doesn't have to come from higher animals.
There is no evidence available that "vegetable oil" is unhealthy in any way, other than the calories.
There is no good evidence for example that "Omega-6" rich oils are inflammatory, quite the contrary, we've got several systematic reviews and meta analyses claiming they are not. And the n-6 : n-3 ratio is completely arbitrary (most ratios in nutrition are). We've got much better evidence for example that saturated fat does raise LDL and that LDL is causal in heart disease.
There's also nothing wrong with eating 6 times per day, unless you end up eating too many calories. If you meant to say that people eat too much, then yes, we do eat too much, but meal frequency has nothing to do with it. Many people can easily eat 4000 kcal in a single meal and those with binging problems often do, so while reducing meal frequency can be a good strategy for some people, it's a poor strategy for others. E.g. OMAD is a recipe for eating disorders.
We do agree that animal products can be part of a healthy diet, it's much easier to get adequate protein from lean meat, eggs are a good source of choline, folate, vitamin A and dairy is a good source of calcium. In the standard diets of the western worlds however, we have no shortage of animal products, what we have is a shortage of whole plants.
Modern grain varieties don't resemble their heritage counterparts. Modern wheat (since the 70's) sees something like 19x the immune response. As to seed oils, frankly I just don't see a need to support heavily processed and refined foods in general, in particular margarine and vegetable shortening.
As far as over-eating and meal frequency... hormones are part of the calculation, you can clear more calories with less hormone response in fewer meals. If you look at tribal cultures with a food abundance (near coastal fish) would only eat once a day or so. Spiking glucose/insuline more times a day isn't so great in general.
I think we're mostly on the same page... I'm more than happy to see people eat more from whole plant meals with a more nose to tail approach to meat consumption. Not to mention a huge a shift in the types and qualities of meat and fish.
I think the level of refined sugars, oils and modern grains are a big problem... so is, for that matter, poorly raised animals and mono-farming in general. Optimizing for yield and efficiency seems to have lost a lot along the way imo.
One aside, while some can eat massively in a single meal... it's very hard for most people to overeat in a single meal. Harder still to do it consuming meat/eggs/fish and greens. Calories count, calories are king in terms of what we eat... and hormone response is queen.
That combined with a huge uptick in constantly eating all the time, sugary drinks, etc... eating 6-8 times a day. Most people can get away with 1-2 meals a day and a small snack or coffee outside those main meal(s). Longer fasting has historically been involuntary and/or religious, has other benefits that should be included pretty regularly as well.
I think animal proteins and fats are good to keep, even just eggs, butter and fish. There's a lot of nutrition in egg yolks, kidney and/or liver meat and it isn't the same from vegetable sources. Animal protein is also a bit different in terms of absorption than vegetable as well. It's not hard for people to get 100-150g of appropriate protein a day on average either and doesn't have to come from higher animals.