We need lots of protein in our diet and the foods that supply these proteins are meat, fish and dairy products. Any diet that excludes these foods must be deficient in protein.
We've discussed that safe and adequate level of protein intake for the general population is 12 to 15 percent of total calories. Therefore, someone consuming 2,000 calories per day has an energy equivalent of 240 to 300 calories (60 to 75 grams) of protein per day. Also most non athletes do well with .8 grams of protein per kilogram of body weight. This can be just about met by eating nothing else but 1 cup of rice and 1 cup of beans three times a day. One package of tofu contains 53 grams of protein (not quite 1.5 cups). We mean to say here that tofu or beans can supply same level of proteins as beef or fish can. Because our body broke down all the proteins into its constituent amino acids, so important is from where the requisite amino acids come and not the source(vegetarian or non-vegetarian).