| ObjectiveThe optimum status of human energy metabolism is to achieve the balance state of energy intake and energy expenditure, which could maintain a certain body size, body composition and maintain long-term health. Because of the changes in dietary and lifestyle patterns, one third of Chinese adults were overweight and obesity, which was showed in the reports of 2002 National Health and Nutrition Survey in China. At the same time, the dietary energy intake had reduced. So we wonder if our currently recommended nutrient intakes (RNIs) for energy are applicable to the current situation. Determination of total energy expenditure is essential for establishing the RNI. In order to accumulate the basic data and assess the validity of the methods for total energy expenditure, we carried out the study in the South and the North of China.MethodsA total of 66 healthy Chinese adults were selected in this study, but four persons who did not complete the whole study were excluded. A total of 62 healthy Chinese adults aged 20-45 y were finally involved in this study (South 32, North 30).The consumption of oxygen and carbon dioxide production was determined by using the portable indirect calorimetry systems-K4b2 (Cosmed, Italy). Urine was collected during the whole consecutive 24h and then we determined urinary nitrogen (g/d). Basal energy expenditure (BEE) was calculated by Weir equation. Then we compared the measured value with estimated value, which calculated by Schoflield equation. Henry equation, Oxford equation, Liu equation and revised Schofiled equation.In the two weeks of energy balance study, we used food weighted method to obtain the net weight of each food intake of the subjects. The food samples were collected by using duplicate portion method for a cycle (3 days). The nutrients in the dietary were determined by using the national standard (Protein:GB/T 5009.5-2003. Fat:GB/T 5009.6-2003. Water:GB/T 14769-1993. Ash:GB/T 5009.4-2003). And content of carbohydrate was calculated by subtration. Total energy intake (TEI) was calculated by net weight of food intake and content of various kinds of nutrients. Total energy expenditure (TEE) was calculated by TEI and weight changes. Physical activity level (PAL) was calculated by TEE/BEE.Energy expenditure of the subjects during 7d was obtained using Lifecorder accelerometer and physical activity record (PAR). The results of TEE collected by the two methods were compared with TEE obtained by energy balance method, to evaluate the validity of the two methods.Results1. K4b2 determination of basal metabolism rate:The average of BEE was 5480±1101 kJ/d, men (6041±1063 kJ/d) was 22.81% higher than women (4919±826 kJ/d, P<0.05). BEE/FFM of men (117.6±14.8kJ/kg) was significantly lower than that of women (130.3±19.6 kJ/kg, P＜0.05). But BEE/BSA of men (3618.3±579.5 kJ/m2) was significantly higher than that of women (3240.9±480.3 kJ/m2, P<0.05). There was no significantly difference in BMR between men (4.2±0.7 kJ/kg-h) and women (3.9±0.7 kJ/kg·h).All of estimated BEEs calculated by Schoflield equation, Henry equation, Oxford equation, Liu equation and revised Schofiled equation were higher than measured value (P<0.05), while BEE calculated by Schoflield equation was highest (9.25% higher than measured value), and BEE calculated by Liu equation and revised Schofiled equation was only 4.09% and 4.16%, respectively higher than measured value. There were no significantly statistical differences in men and women, but the BEE calulated by the revised Schofield equation was still 5.45% higher in men and 2.57% in women.2. Energy balance:The average TEE was 9230±2231kJ/d, which was significantly higher in men (10934±1734 kJ/d) than in women (7605±965 kJ/d). The average TEE of south subjects was 9000±1966kJ/d, which was significantly higher in men (10320±1706kJ/d) than in women (7680±1167 kJ/d, P<0.05). The average TEE of north subjects was 9476±2492kJ/d, which was significantly higher in men (11589±1560kJ/d) than in women (7524±723kJ/d, P＜0.05). TEE of sedentary, light, moderate and vigorious physical activity level in men was 8147±1223kJ/d, 10121±1342 kJ/d,11389±913 kJ/d and 12109±1485 kJ/d, respectively. TEE of sedentary, light, moderate physical activity level in women was 7075±8893kJ/d, 7557±858kJ/d, and 8162±1047kJ/d, respectively. 3. Comparison of different methods:Comparing with the energy balance method, TEE was 8.86% lower by Lifecorder. TEE in men was 14.99%(1639±1497 kJ/d, P <0.0001) lower, while men in the South was 8.75%(P=0.023) lower, men in the North was 20.93%(P＜0.0001). There was no significant difference of TEE between energy balance method and Lifecorder method in women. TEE measured by Lifecorder in sedentary PAL of men was 13.88%(P=0.024) higher than that measured by energy balance method, but in moderate and vigrious PAL of men was 19.96% and 21.60%(P＜0.0001) respectively lower than that measured by energy balance method. There was no significant difference between the two methods in light PAL of men and the three PALs of women.Comparing with the energy balance method, TEE was 9.90% higher by physical activity record (PAR). There was no significant difference of TEE between the two methods in men. But TEE of PAR was 23.57% higher in women (P＜0.0001), while women in the South was 7.77%(P=0.021) higher and who in the North was 40.77% (P<0.0001). TEE measured by PAR in sedentary PAL of subjects was higher than that measured by energy balance method, while that in men was 20.92%(P=0.010) and in women was 50.16%(P=0.005). TEE measured by PAR in light PAL of women was 16.55%(P=0.004) higher. There was no significant difference between the two methods in moderate PAL of women and the three PALs of men.Conclusions1. All of estimated BEE calculated by Schoflield equation, Henry equation, Oxford equation, Liu equation and revised Schofiled equation are higher than measured value.2. Energy balance method can determine the energy expenditure correctly. It also can observe the state of enengy balance of subjects in different PAL, which can provide reference for establishing RNI of energy and physical activity guideline.3. TEE measured by Lifecorder of light PAL subjects is close to that of energy balance method, but when the physical activity is at the high level, Lifecorder will underestimate TEE, and the higher PAL, the more underestimated. Although 7d PAR method can estimate TEE of people in group simplely and conveniently, it has limitations in estimating TEE of individual. |
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