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Substrate utilization during exercise in formerly morbidly obese women.
N R Guesbeck1, M S Hickey, K G MacDonald
1Human Performance Laboratory, East Carolina University, Greenville, North Carolina 27858, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 22, 2001
Summary
Weight loss in morbidly obese women significantly reduces fat utilization during exercise. This impaired lipid oxidation may contribute to obesity development, highlighting the importance of metabolic adaptations post-weight loss.
Area of Science:
- Metabolic Adaptations
- Obesity Research
- Exercise Physiology
Background:
- Morbid obesity is a complex metabolic disorder.
- Weight loss surgery aims to improve metabolic health.
- Understanding substrate utilization post-weight loss is crucial.
Purpose of the Study:
- To compare substrate utilization during fasting and exercise in women after weight loss (WL) versus weight-matched controls (C).
- To assess energy intake and expenditure in both groups.
- To investigate potential metabolic defects contributing to obesity.
Main Methods:
- Participants included morbidly obese women approximately 24 months post-gastric bypass surgery (WL) and weight-matched controls (C).
- Substrate utilization was measured during fasting and submaximal exercise (absolute and relative intensities) using respiratory exchange ratio.
- Energy expenditure was assessed using the (2)H(2)(18)O method; energy intake was self-reported.
Main Results:
- The respiratory exchange ratio was significantly higher in WL during both absolute and relative intensity exercise, indicating lower fat utilization.
- Fat utilization was markedly reduced in WL women (29.7% vs. 53.2% at absolute intensity; 12.4% vs. 34.3% at relative intensity).
- No significant differences were observed in resting substrate utilization, daily energy expenditure, or macronutrient intake between groups.
Conclusions:
- Lipid oxidation is significantly depressed during physical activity in women who have undergone weight loss surgery.
- This impaired fat utilization during exercise may be a contributing factor to the propensity for developing morbid obesity.
- Further research is needed to explore therapeutic strategies targeting lipid metabolism during exercise.
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