Background: Metabolic rate is known to rise above basal levels after eating, especially following protein consumption. Yet, this postprandial rise in metabolism appears to vary among individuals. This study examined changes in energy expenditure in response to ingestion of a high protein, high fat (HPHF) meal versus an isocaloric high protein, low fat (HPLF) meal in underweight, normal weight, or overweight females (n = 21) aged 19-28 years.

Methods: Energy expenditure, measured using indirect calorimetry, was assessed before and every 30 minutes for 3.5 hours following consumption of the meals on two separate occasions. Height and weight were measured using standard techniques. Body composition was measured using bioelectrical impedance analysis.

Results: Significant positive correlations were found between body mass index (BMI) and baseline metabolic rate (MR) (r = 0.539; p = 0.017), between body weight and baseline MR (r = 0.567; p = 0.011), between BMI and average total change in MR (r = 0.591; p = 0.008), and between body weight and average total change in MR (r = 0.464; p = 0.045). Metabolic rate (kcal/min) was significantly higher in the overweight group than the normal weight group, which was significantly higher than the underweight group across all times and treatments. However, when metabolic rate was expressed per kg fat free mass (ffm), no significant difference was found in postprandial energy expenditure between the overweight and normal groups. Changes in MR (kcal/min and kcal/min/kg ffm) from the baseline rate did not significantly differ in the underweight (n = 3) or in the overweight subjects (n = 5) following consumption of either meal at any time. Changes in MR (kcal/min and kcal/min/kg ffm) from baseline were significantly higher in normal weight subjects (n = 11) across all times following consumption of the HPHF meal versus the HPLF meal.

Conclusion: There is no diet-induced thermogenic advantage between the HPHF and HPLF meals in overweight and underweight subjects. In contrast, in normal weight subjects, ingestion of a HPHF meal significantly increases MR (69.3 kcal/3.5 hr) versus consumption of a HPLF meal and provides a short-term metabolic advantage.

Figure 2: Mean (± SE) baseline and postprandial metabolic rate (kcal/min) among overweight, normal weight, and underweight subjects before and following consumption of a high protein, low fat (HPLF) meal.

Mentions:
There was a significant (p = 0.0003) effect of BMI classification on absolute (kcal/min) energy expenditure. This was true prior to (at baseline) and after consumption of the meals (Figures 1 and 2). Overall, individuals classified as overweight (1.20 ± 0.01 kcal/min) showed a greater level of energy expenditure as compared to individuals classified as normal weight (1.08 ± 0.01 kcal/min). Likewise, normal weight individuals showed greater energy expenditure than underweight individuals (0.92 ± 0.02 kcal/min) across all times and treatments. When energy expenditure was expressed as kcal/min/ffm, there was no difference among groups at baseline, but a significant (p = 0.0001) effect of BMI classification across all postprandial times and treatments (Table 2). However, when expressed in this manner (representing average energy expenditure over 210 minutes across both treatments), the difference in energy expenditure between overweight (0.025 ± 0.0003 kcal/min/kg ffm) and normal weight groups (0.024 ± 0.0002 kcal/min/kg ffm) was corrected. The energy expenditure of underweight group 0.022 ± 0.0005 kcal/min/kg ffm) was still significantly less than the other two groups across all times and treatments.

Figure 2: Mean (± SE) baseline and postprandial metabolic rate (kcal/min) among overweight, normal weight, and underweight subjects before and following consumption of a high protein, low fat (HPLF) meal.

Mentions:
There was a significant (p = 0.0003) effect of BMI classification on absolute (kcal/min) energy expenditure. This was true prior to (at baseline) and after consumption of the meals (Figures 1 and 2). Overall, individuals classified as overweight (1.20 ± 0.01 kcal/min) showed a greater level of energy expenditure as compared to individuals classified as normal weight (1.08 ± 0.01 kcal/min). Likewise, normal weight individuals showed greater energy expenditure than underweight individuals (0.92 ± 0.02 kcal/min) across all times and treatments. When energy expenditure was expressed as kcal/min/ffm, there was no difference among groups at baseline, but a significant (p = 0.0001) effect of BMI classification across all postprandial times and treatments (Table 2). However, when expressed in this manner (representing average energy expenditure over 210 minutes across both treatments), the difference in energy expenditure between overweight (0.025 ± 0.0003 kcal/min/kg ffm) and normal weight groups (0.024 ± 0.0002 kcal/min/kg ffm) was corrected. The energy expenditure of underweight group 0.022 ± 0.0005 kcal/min/kg ffm) was still significantly less than the other two groups across all times and treatments.

Background: Metabolic rate is known to rise above basal levels after eating, especially following protein consumption. Yet, this postprandial rise in metabolism appears to vary among individuals. This study examined changes in energy expenditure in response to ingestion of a high protein, high fat (HPHF) meal versus an isocaloric high protein, low fat (HPLF) meal in underweight, normal weight, or overweight females (n = 21) aged 19-28 years.

Methods: Energy expenditure, measured using indirect calorimetry, was assessed before and every 30 minutes for 3.5 hours following consumption of the meals on two separate occasions. Height and weight were measured using standard techniques. Body composition was measured using bioelectrical impedance analysis.

Results: Significant positive correlations were found between body mass index (BMI) and baseline metabolic rate (MR) (r = 0.539; p = 0.017), between body weight and baseline MR (r = 0.567; p = 0.011), between BMI and average total change in MR (r = 0.591; p = 0.008), and between body weight and average total change in MR (r = 0.464; p = 0.045). Metabolic rate (kcal/min) was significantly higher in the overweight group than the normal weight group, which was significantly higher than the underweight group across all times and treatments. However, when metabolic rate was expressed per kg fat free mass (ffm), no significant difference was found in postprandial energy expenditure between the overweight and normal groups. Changes in MR (kcal/min and kcal/min/kg ffm) from the baseline rate did not significantly differ in the underweight (n = 3) or in the overweight subjects (n = 5) following consumption of either meal at any time. Changes in MR (kcal/min and kcal/min/kg ffm) from baseline were significantly higher in normal weight subjects (n = 11) across all times following consumption of the HPHF meal versus the HPLF meal.

Conclusion: There is no diet-induced thermogenic advantage between the HPHF and HPLF meals in overweight and underweight subjects. In contrast, in normal weight subjects, ingestion of a HPHF meal significantly increases MR (69.3 kcal/3.5 hr) versus consumption of a HPLF meal and provides a short-term metabolic advantage.