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The Plateau Effect in Waist Circumference and Body Composition: The Rule of First Order Change
Author(s) -
Hargrove James L.,
Heinz Grete
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.872.3
Subject(s) - waist , circumference , anthropometry , zoology , mathematics , plateau (mathematics) , kinetics , body weight , body mass index , statistics , medicine , endocrinology , chemistry , biology , physics , geometry , mathematical analysis , quantum mechanics
Dieters and weight‐lifters find that rates of weight loss or weight gain are rapid when a new training program is started, but that the rate diminishes until a plateau is reached. The plateau can be explained if anthropometric measures follow apparent first order kinetics in which change is modeled with a fixed input (food or new synthesis of body mass) and first order rate of loss. We used statistical software to test whether rates of change in body proportion from The Biology of Human Starvation by Ancel Keys et al.(1950) follow first order kinetics. The study began with 2 wks of food intake of 3400 kcal that was decreased to 1600 kcal for 24 weeks. Thereafter, food intake was increased in steps back to normal levels. Essentially all anthropometric and physiological measures showed rapid initial change that slowed as the study progressed. The data for body mass, fat mass, waist and limb girths, strength and urinary N excretion fit well to models based on first order (exponential) decline. First order rate parameters were not identical for different indices. For example, the rate parameter for waist circumference was 0.11 wk −1 but for fat mass it was 0.049 wk −1 . During the refeeding phase, the regain also fit a model based on first order kinetics. The data are consistent with the concept that a number of anthropometric and physiological variables can be modeled on the assumption that change follows first order kinetics.