Originally Posted by lillypad
You make a lot of good points in your statement. However I do have to disagree with a couple of them. First, the vegetarian diet is not necessarily lower in calories. It depends on what kind of vegetables you are consuming. If you are eating primarily leaves and greens then yes you are correct. However if you are consuming beans, potatoes, and corn, it can be just as high as the average American's diet and it is still considered to be vegetarian. Oils from plant sources can also raise your total in a hurry. You have to be consuming something with some calories or you would soon wither away to nothing but a toothpick.
Next, to be on a low-carb diet you don't have to be consuming a wheelbarrow load of animal fat on a daily basis. You don't have to focus your diet on red meat or any other type of large production farm-raised animals.
A vegan diet without any animal products will be lower in calories due to the bulk needed to consume equal amounts of calories and the water content of the foods. Calories of carbohydrates are 4/gram and fat is 9/gram. Protient (in the US) is primarily tied to fat. Most proponents of low carb diets push a high fat diet to induce ketosis and the studies cited here show that the levels of fat in these ketogenic diets are very high. One site, The Omnivore, advocates a very high saturated fat diet as more to what the human species evolved to eat. Low fat, low carbs will also mean low protien unless you want to eat your fish. If there were a major shift in American eating patterns of protien tomorrow the oceans would be depopulated wastelands with no life. Just look at the situation on the Grand Banks and the Atlantic Cod.