Year of Publication

2020

Degree Name

Master of Science in Nutrition and Food Systems (MSNFS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Dietetics and Human Nutrition

First Advisor

Dr. Kyle Flack

Abstract

Background: Exercise induced weight loss is often less than expected due to a coordinated set of compensatory mechanisms that serve to maintain energy homeostasis. The extent to which exercise frequency, duration, intensity and exercise energy expenditure (ExEE) influences the compensatory response to an exercise-induced energy deficit (energy compensation) is controversial. Determining how these variables impact energy compensation would help health care providers prescribe exercise with greater probability of creating a sustained negative energy balance and subsequent weight loss.

Methods: 44 Overweight/obese men and women (BMI=25-35kg/m²) aged 18 to 40 years were randomized to perform aerobic exercise 2 or 6 days/week or into a sedentary control group for 12 weeks. Changes in body composition and rates of energy expenditure at rest and during physical activity were assessed. Exercise sessions were evaluated for duration, intensity, and ExEE. Energy compensation was determined by comparing changes in bodily energy stores to total ExEE and expressed as both % energy compensated (compensation index, CI) and total energy compensated (kcal).

Results: No differences in energy compensation (CI or total energy compensated) were observed between groups exercising two or six days per week. ExEE, time spent exercising per week, or exercise intensity did not influence CI or total energy compensated. Greater fat mass was lost (-1.77 kg) when weekly ExEE exceeded 2,000 kcal compared to under 2,000 kcal (-0.41 kg, p< 0.05), ExEE predicted % fat mass loss (p< 0.05) when controlling for total energy compensated.

Conclusion: Greater exercise intensity, frequency, ExEE or exercise duration do not promote greater energy compensation when expressed as CI or total energy compensated. When energy compensated is held constant, greater ExEE promote fat mass loss. ExEE over 2,000 kcal/week is needed to overcome the compensatory response and reduce fat mass.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.127

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