Dieting is the practice of ingesting food in a regulated fashion to achieve or maintain a controlled weight. In most cases the goal is weight loss in those who are overweight or obese, but some athletes aspire to gain weight (usually in the form of muscle) and diets can also be used to maintain a stable body weight.
The energy humans get from food is limited by the efficiency of digestion and the efficiency of utilization. The efficiency of digestion is largely dependent on the type of food being eaten. Poorly chewed seeds are poorly digested. Refined sugars and fats are absorbed almost completely. Chewing does not compensate for the calorie content of a food that is eaten, even celery, which is primarily indigestible cellulose, contains enough sugars to easily compensate for the cost of chewing it.
Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by a gene and encoded in the genetic code. Although this genetic code specifies 20 standard amino acids plus selenocysteine and in certain archaea pyrrolysine, the residues in a protein are sometimes chemically altered in post-translational modification.
This can happen either before the protein is used in the cell, or as part of control mechanisms. Proteins can also work together to achieve a particular function, and they often associate to form stable complexes. In organic chemistry, an unsaturated compound is a chemical compound that contains carbon - carbon pi bonds such as an alkene or an alkyne.In a saturated compound these pi bonds are removed by the addition of hydrogen and no multiple bonds are present. Alkanes are examples of saturated compounds.
Fatty acids are aliphatic monocarboxylic acids, derived from, or contained in esterified form in an animal or vegetable fat, oil or wax. Natural fatty acids commonly have a chain of 4 to 28 carbons (usually unbranched and even numbered), which may be saturated or unsaturated. By extension, the term is sometimes used to embrace all acyclic aliphatic carboxylic acids.
This would include acetic acid, which is not usually considered a fatty acid because it is so short that the triglyceride triacetin made from it is substantially miscible with water and is thus not a lipid. Deficiencies in Vitamin B12, a bacterial product that cannot be reliably found in plant foods,can have serious health consequences, including anemia and neurodegenerative disease.
Although clinical B12 deficiency is rare in vegans, if a person has not eaten more than the daily needed amount of B12 over a long period before becoming a vegan then they may not have built up any significant store of the vitamin. In a 2002 laboratory study, more of the strict vegan participants B12 and iron levels were compromised than those of lacto- or lacto-ovo-vegetarian participants.
According to the US National Institute of Health, with appropriate food choices, vegan diets can be adequate for children at all ages.The American Dietetic Association also considers well-planned vegan diets appropriate for all stages of the life cycle, including pregnancy and lactation, but recommends that vegan mothers supplement for iron, vitamin D, and vitamin B12, Vitamin B12 deficiency in lactating vegetarian mothers has been linked to deficiencies and neurological disorders in their children.
The possible beneficial health effects of tea consumption have been suggested and supported by some studies, but others have found no beneficial effects. The studies contrast other claims, including antinutritional effects such as preventing absorption of iron and protein, usually attributed to tannin. The vast majority of studies have been of green tea.
However, some studies have been made of the other types of tea derived from Camellia sinensis, such as white, oolong, and black tea. Green tea has been claimed to be helpful for atherosclerosis, LDL cholesterol, cancer, inflammatory bowel disease, diabetes, liver disease, weight loss,neuro degenerative diseases, and even halitosis.