How fat are you?Joan Conway and her colleagues are pioneering a new method for measuring total body fat. They shine near-infrared light on the skin at selected body sites, and then, using a spectrophotometer spectrophotometer, instrument for measuring and comparing the intensities of common spectral lines in the spectra of two different sources of light. See photometry; spectroscope; spectrum. , measure the degree to which that light is absorbed or modified b irradiated tissue within 1 or 2 centimeters of the skin surface. Since fat, water and protein each absorb most efficiently different spectral frequencies, one can focus on fat's peak interacting wavelengths to gauge total body fat, explains Conway. These "infrared interactance" measurements are made at 1-nanometer intervals between about 750 and 1,100 nm. It takes less than a minute to scan the range of frequencies at each body site, using a 2-centimeter-diameter fiber-optic cable, which also transmits the tissue-altered frequencies back for analysis. Although Conway now averages readings from five sites to calculate total body fat, her data--based on a survey of more than 200 peope aged 19 to 65--show these five-site averages to be virtually identical to biceps-fat readings alone. Conway says her data show the technique is more accurate than the commonly used calipered measurement of pinched skin folds Skin folds are areas of skin where it folds. Many skin folds are distinct, heritable anatomical features, and may be used for indentification of animal species, while others are non-specific and may be produced either by individual development of an organism or by arbitrary , and is more reliable than the electrical-impedence technique (which, because it measures the body's electrical conductivity Not to be confused with electrical conductance, a measure of an object's or circuit's ability to conduct an electric current between two points, which is dependent on the electrical conductivity and the geometric dimensions of the conducting object. , can be affected by such factors as blood flow, body water content and body sales content). In fact, Conway's studies show that her technique gives fat calculations within 3 percent of the best techniques--deuterium oxide dilution and underwater weighing. Moreover, where deuterium oxide deuterium oxide n. An isotopic form of water with composition D2O, isolated for use as a moderator in certain nuclear reactors. deuterium oxide Noun same as heavy water dilution requires drawing blood and underwater weighing requires immersion in a calibrated cal·i·brate tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates 1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): pool, the infrared technique can be completed in three minutes "Three Minutes" is the 46th episode of Lost. It is the twenty-second episode of the second season. The episode was directed by Stephen Williams, and written by Edward Kitsis and Adam Horowitz. It first aired on May 17, 2006 on ABC. and may ultimately require no more than the rolling up of one's sleeve. Conway's system, the only one of its kind in existence, now sprawls sprawl v. sprawled, sprawl·ing, sprawls v.intr. 1. To sit or lie with the body and limbs spread out awkwardly. 2. across a desktop. But she expects that within tow or three years a commercial version, perhaps only the size of a thick paperback book, could be available. |
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