Figure 1.

Changes from baseline in energy balance and homeostatic systems during maintenance of a 10% or greater reduced body weight and responsiveness to exogenous leptin in individuals who initially had obesity or never had obesity (9). Energy expenditure owing to physical activity is calculated as the difference between direct measurement of 24-hour energy expenditure and measurement of resting energy expenditure plus diet-induced thermogenesis. Eating behavior, including energy intake, is examined by visual analog scales during a fixed liquid formula meal, kilocalories of the liquid formula consumed to reach satiation, and functional MRI (fMRI) studies of brain responses to food. Assessments of autonomic nervous system activity were made by analyses of heart rate variability during sequential blockade of the PNS and SNS with atropine and esmolol, respectively, and by 24-hour urine catecholamine excretion. Skeletal muscle contractile efficiency was measured by graded bicycle ergometry. MHC and SERCA muscle gene expression studies were done by mRNA quantification in biopsies of vastus lateralis muscle. Entries in bold are at least partially reversed by leptin repletion in weight-reduced individuals. MCH, myosin heavy chain; PNS, parasympathetic nervous system; rT3, reverse T3; SERCA, sarcoplasmic endoplasmic reticulum Ca⁺⁺-dependent ATPase; SNS, sympathetic nervous system; T3, triiodothyronine; T4, thyroxine; TSH, thyroid stimulating hormone.