Byrne, NM and Wood, RE and Schutz, Y and Hills, AP, Does metabolic compensation explain the majority of less-than-expected weight loss in obese adults during a short-term severe diet and exercise intervention?, International Journal of Obesity, 36, (11) pp. 1472-1478. ISSN 0307-0565 (2012) [Refereed Article]
Objective: We investigated to what extent changes in metabolic rate and composition of weight loss explained the less-than-expected weight loss in obese men and women during a diet-plus-exercise intervention.
Design: In all, 16 obese men and women (41 ± 9 years; body mass index (BMI) 39 ± 6 kg m−2) were investigated in energy balance before, after and twice during a 12-week very-low-energy diet (565–650 kcal per day) plus exercise (aerobic plus resistance training) intervention. The relative energy deficit (EDef) from baseline requirements was severe (74%–87%). Body composition was measured by deuterium dilution and dual energy X-ray absorptiometry, and resting metabolic rate (RMR) was measured by indirect calorimetry. Fat mass (FM) and fat-free mass (FFM) were converted into energy equivalents using constants 9.45 kcal per g FM and 1.13 kcal per g FFM. Predicted weight loss was calculated from the EDef using the '7700 kcal kg−1 rule'.
RESULTS: Changes in weight (-18.6 ± 5.0 kg), FM (-15.5 ± 4.3 kg) and FFM (-3.1 ± 1.9 kg) did not differ between genders. Measured weight loss was on average 67% of the predicted value, but ranged from 39% to 94%. Relative EDef was correlated with the decrease in RMR (R = 0.70, P < 0.01), and the decrease in RMR correlated with the difference between actual and expected weight loss (R = 0.51, P < 0.01). Changes in metabolic rate explained on average 67% of the less-than-expected weight loss, and variability in the proportion of weight lost as FM accounted for a further 5%. On average, after adjustment for changes in metabolic rate and body composition of weight lost, actual weight loss reached 90% of the predicted values.
CONCLUSION: Although weight loss was 33% lower than predicted at baseline from standard energy equivalents, the majority of this differential was explained by physiological variables. Although lower-than-expected weight loss is often attributed to incomplete adherence to prescribed interventions, the influence of baseline calculation errors and metabolic downregulation should not be discounted.
|Item Type:||Refereed Article|
|Research Division:||Medical and Health Sciences|
|Research Group:||Human Movement and Sports Science|
|Research Field:||Exercise Physiology|
|Objective Group:||Public Health (excl. Specific Population Health)|
|Objective Field:||Public Health (excl. Specific Population Health) not elsewhere classified|
|Author:||Byrne, NM (Professor Nuala Byrne)|
|Author:||Hills, AP (Professor Andrew Hills)|
|Web of Science® Times Cited:||20|
|Deposited By:||Health Sciences|
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