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Discrepancy between self-reported and actual caloric intake and exercise in obese subjects
S W Lichtman1, K Pisarska, E R Berman
1Department of Medicine, St. Luke's-Roosevelt Hospital Center, Columbia University College of Physicians and Surgeons, New York, NY.
The New England Journal of Medicine
|December 31, 1992
Summary
Obese individuals who struggle to lose weight often underreport their calorie intake and overestimate physical activity. Their energy expenditure is typically normal, not the cause of diet resistance.
Area of Science:
- Obesity Research
- Metabolic Studies
Background:
- Some obese individuals fail to lose weight despite reporting very low caloric intake (<1200 kcal/day).
- Two primary hypotheses for this diet resistance include low total energy expenditure and underreporting of caloric intake.
Purpose of the Study:
- To investigate the reasons behind apparent diet resistance in obese subjects.
- To differentiate between low energy expenditure and inaccurate intake reporting as causes of failed weight loss.
Main Methods:
- Studied 224 obese subjects, comparing a group with a history of diet resistance (Group 1) to a control group (Group 2).
- Evaluated total energy expenditure, thermic effects of food and exercise, and actual energy intake using indirect calorimetry and body composition analysis over 14 days.
- Assessed self-reported physical activity and eating behaviors.
Main Results:
- Subjects with diet resistance (Group 1) had total energy expenditure and resting metabolic rate within predicted values.
- No significant differences in the thermic effects of food or exercise were found between groups.
- Group 1 significantly underreported caloric intake (47%) and overreported physical activity (51%).
- Group 1 subjects perceived a genetic cause for obesity and frequently used thyroid medication.
Conclusions:
- Failure to lose weight in some obese individuals is primarily due to substantially higher energy intake than reported, not abnormalities in thermogenesis.
- Overestimation of physical activity also contributes to the discrepancy between reported and actual energy balance.
- These findings highlight the importance of accurate dietary assessment in managing obesity.