In the right quantities, meat is good for you. We evolved to eat and digest it for a reason. Unfortunately, the average American diet consists of entirely too much meat, especially red meat, and not enough of other food groups, so it's deceptively easy to say a vegetarian diet is clearly healthier. But this is not necessarily so; vegetarians who do not carefully monitor their intake of protein and other nutrients can suffer from malnutrition. It happens that people who have chosen a vegetarian diet are typically more attentive to what they consume, making them, on average, healthier than someone who hasn't made any specific choices about their eating.

A diet philosophy is only as good as the effort one is willing to put into it. Someone who eats meat regularly but sparingly, limits oils and sugars, and ensures they eat enough of the other food groups is probably going to be comparably healthy to a vegetarian or vegan with the same commitment to eating well.

You can get by as an ovo vegetarian no problem, but other than that there are things in meat that your body cannot do without.

I suppose it depends on what purpose you're building your diet around. For me, vegetarianism definitely isn't the best choice.

To get the best nutrition, you need a balanced, variety of foods. *

A vegetarian diet gives me gas ;)

I'd like to make an argument from taste.

While a vegan diet can compare to an animal-based one nutritionally (See: link) I would argue that it cannot successfully replicate many of the flavours and textures that a lover of food might enjoy, further I would argue that the taste of certain animal-based dishes, and indeed most of the flavours we obtain from animals' meats, oils, secretions, and bones are worth saving in our culture's food preparations.

For example, in soups the most important component is the base. The base is most often a stock made using bones and marrow with vegetables. You can use only vegetables in the base but you will be missing a vital savoury component. Some cooks use demi glace in place of, or along with, the base. It isn't as simple as using soy or mushrooms for the missing savoury component, because these products have their own flavours. You are at this point trying substitution.

In gravy and sauces, a vital ingredient is the butter, lard or meat drippings (fat). If you use only a vegetable-based oil, you will be sorely disappointed with the result as compared to its animal-based equivalent (also, NEVER use margarine in a roux). The next component is either stock prepared as mentioned in the preceding paragraph, milk, or another ingredient like tomato sauce. In the vast majority of cases you will need a bone-based stock.

In sweet baked goods texture is often heavily influenced by butter, margarine may act as a substitute but it produces its own texture effect (usually chewier, or fluffier/softer). In certain goods you CANNOT substitute (anyone who has made a croissant for example knows this) because it is a matter of chemistry. Eggs are another vital ingredient that is very tricky to emulate the chemistry of by substitute, but from my experience there are some clever substitutes that may solve certain problems that eggs are required for in the dish (such as using starch, or guar gum-containing marketed substitute, to create some degree of binding). If you're making a meringue, an inferiour substitute is singed liquid marshmallow.

As a matter of meat itself, it is very difficult to emulate meat so that it doesn't taste like a substitute. This is the holy grail, as a matter of fact, for the vegan chef. For example, if you wish to emulate ground meat it isn't as difficult as a cut of steak. This is because ground meat has most of its texture stripped away, so it's merely a matter of creating firmness, savoury flavour, and the proper mouthfeel. To this end many vegan chefs have successfully emulated ground meat, which is laudible, using mushrooms, yeast and soy extracts, cereals and grains, and varieties of tofu. What hasn't been done is the full emulation of a steak or cut of meat, because for obvious reasons the texture simply cannot be replicated in a kitchen. I should add that by sheer fortune the sulfur-shelf mushroom, otherwise known as the chicken of the woods, is supposedly a very convincing substitute to poultry in taste and texture. I cannot confirm this through personal experience, as the only time I found one, it was too old and grew too high on an oak tree for me to use.

Candies are the final item I wish to mention. It is clear that one may obtain easily dark chocolate that is free of animal products, indeed only poor-quality dark chocolate has milkfat, however milk chocolate itself requires animal products, as does fudge. I am not convinced that one can easily substitute these ingredients without compromising the product. Perhaps the product most likely to suffer are truffles and other heavy cream-based candies, as the filling requires a fat that gives a silky texture and cream seems to work best for this.

There's nothing wrong with a vegetarian diet, if you do it right. (I do know one girl who had to stop due to medical reasons; she was trying to eat more beans, nuts, etc. but her body wasn't taking it well.)

But there's nothing that makes it better than an omnivorous diet. Meat is okay, even good for you in proper quantities (as it is with many types of food). An only white meat diet might be good to try out. But a monitored, balanced diet with a proper quantity of meat is very healthy, and is not worse than a vegetarian diet.

Fasting is the way to go. A diet of vegetables is healthy but it is not going to reduce the weight.