The recipient also trusts that the medical history of the donor and her family is accurate. This factor of trust should not be underestimated in importance. Donors in the US are paid thousands of dollars; such compensation may attract unscrupulous individuals inclined to conceal their true motivations. However, a full psychological evaluation is required by most IVF clinics, giving an indication if the donor is trustworthy or not. In more cases than not, there is no ongoing relationship between the donor and recipient following the cycle. Both the donor and recipient agree in formal legal documents that the donation of the eggs is final at the time of retrieval, and typically both parties would like any "relationship" to conclude at that point; if they prefer continued contact, they may provide for that in the contract. Even if they prefer anonymity, however, it remains theoretically possible that in the future, some children may be able to identify their donor(s) using DNA databanks and/or registries (e.g., if the donor submits her DNA to a genealogy site and a child born from her donation later submits its DNA to the same site). Multiple birth is a common complication. Incidence of twin births is very high. At the present time, the American Society for Reproductive Medicine recommends that no more than 1 or 2 embryos be transferred in any given cycle. Remaining embryos are frozen, whether for future transfers if the first one fails, for siblings, or for eventual embryo donation.
Thus, when fatty acids are being broken down for energy, all of the remaining glucose is made available for use by the brain.After two or three days of fasting, the liver begins to synthesize ketone bodies from precursors obtained from fatty acid breakdown. The brain uses these ketone bodies as fuel, thus cutting its requirement for glucose. After fasting for three days, the brain gets 30% of its energy from ketone bodies. After four days, this may increase to 70% or more. Thus, the production of ketone bodies cuts the brains glucose requirement from 80 g per day to 30 g per day, about 35% of normal, with 65% derived from ketone bodies. But of the brains remaining 30 g requirement, 20 g per day can be produced by the liver from glycerol (itself a product of fat breakdown). This still leaves a deficit of about 10 g of glucose per day that must be supplied from another source; this other source will be the bodys own proteins. After exhaustion of fat stores, the cells in the body begin to break down protein. This releases alanine and lactate produced from pyruvate, which can be converted into glucose by the liver. Since much of human muscle mass is protein, this phenomenon is responsible for the wasting away of muscle mass seen in starvation. However, the body is able to choose which cells will break down protein and which will not.