[wizofaus]

"fresh vegetables are more expensive since their shelf lives are a lot shorter"

Certainly if you have sufficient storage, it's possible to buy meat in bulk quite cheaply, some of which might even be cheaper per kg (or per calorie?) than many vegetables, but if you stick to in-season vegies and cook them sensibly (into dishes that last a while), on average they're still going to be cheaper than meat. Plenty are in the order of $1-$2/kg in Aus. (potatoes, onions, pumpkin etc.) - I don't know any meat that cheap.

[drorco]

I'm no dietitian but how much nutrition there actually is per 1kg of beef compared to 1kg of potatoes/pumpkin/onions, etc.?

My sister is vegan, and whenever we have a vegan meal, I'm already hungry 2 hours after the meal. On the other hand, if I eat a burger for lunch, I might not be even hungry by dinner time. Again, I'm not a dietitian so I'm pretty ignorant about these things, but if it has to do with proteins, I think the ROI for meat proteins is going to be a lot higher compared to vegetables.

I realize this gets complicated, but just another counter argument for ROI of meat compared to vegetables.

[wizofaus]

Certainly meat tends to have much higher fat and protein density, and hence calorific density than vegetables, but the latter invariably have higher carbohydrate content (meat is essentially 0). Multigrain bread can have much the same calorific density as beef, and nuts are often considerably higher (admittedly, they're typically quite pricey per kg, though not more so than quality cuts of meat). I've personally not observed any significant difference in the quantity of food I eat between vegan/ vegetarian/meat-based meals, though I very rarely eat meals that meat makes up more than a small percentage of. It's actually the micronutrients you need to be more aware of if you're on a strictly vegan diet, which are unlikely to make a difference in food cost (e.g. B12 supplements are about $9 for a gram, but that can last you months).