Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food Science and Human Nutrition

First Advisor

Rick L. Sharp


Obesity occurs when energy intake exceeds energy expenditure over an extended period of time. Low resting metabolic rate (RMR), or expending less energy at rest than persons of equivalent body size, is considered a risk factor for weight gain leading to obesity. However, because obese persons tend to have greater lean mass (LM) as well as fat mass (FM) than do lean individuals, absolute RMR tends to be higher, rendering the detection of initial impairments in RMR difficult. Purposes of this study were to determine resting energy expenditure (REE) in lean and obese women who were matched for LM and investigate differences in activity energy expenditure (AEE) and daily patterns of activity between the two groups. Twenty healthy, nonsmoking, pre-menopausal women (10 lean and 10 obese, matched for LM) participated in this 14-day observational study on free-living energy balance. REE was measured by indirect calorimetry, AEE and total energy expenditure (TEE) were calculated using doubly labeled water, and activity patterns were investigated using two activity monitors. REE was similar in the obese vs. lean women (1601 +/- 109 vs. 1505 +/- 109 kcal/d, respectively, P=.12, adjusting for LM and FM). TEE and AEE were both lower in the obese women (2,414 +/- 126 vs. 2,698 +/- 126 kcal/d, P=.02; 550 +/- 133 vs. 943 +/- 133 kcal/d, P=.09; respectively, adjusting for LM). Obese women sat 2.5 hours more each day (12.7 +/- 3.2 h vs. 10.1 +/- 2.0 h, P<.05), stood 2 hours less (2.7 +/- 1.0 h vs. 4.7 +/- 2.2 h, P=.02) and spent half as much time being physically active than lean women (2.6 +/- 1.5 h vs. 5.4 +/- 1.9 h, P=.002). Findings from this study indicate that REE was not lower in this group of obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including modification of posture allocation, an additional 300 kcal could be expended every day.



Digital Repository @ Iowa State University,

Copyright Owner

Darcy LaRae Johannsen



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File Format


File Size

125 pages