The accuracy and noninvasive nature of the doubly labeled water (DLW) method makes it ideal for the study of human energy metabolism in free-living conditions. However, the DLW method is not always practical in many developing and Asian countries because of the high costs of isotopes and equipment for isotope analysis as well as the expertise required for analysis. This review provides information about the theoretical background and practical aspects of the DLW method, including optimal dose, basic protocols of two- and multiple-point approaches, experimental procedures, and isotopic analysis. We also introduce applications of DLW data, such as determining the equations of estimated energy requirement and validation studies of energy intake.

This study examined the relationship among socioeconomic factors, frequency of food away from home (FAFH) and food-consumption patterns of 1,070 housewives, and the association of those factors with obesity, using data from the third Korea National Health and Nutrition Examination Survey. Although lower intakes of fruits, meats, and fast foods were associated with seldom eating out, no consistent pattern was observed regarding the relationship between the frequency of FAFH and food consumption for all groups of housewives. Further analysis indicated that obesity rates were lower among housewives aged 20-49 years with 7-12 years of education and moderate eating-out frequency, compared to older, less educated women. It appeared that reducing the frequency of FAFH does not always entail desirable food intakes among full-time housewives in Korea. Our findings suggest that choosing healthy meals away from home is more important for housewives than refraining from eating out.

The effects of exercise training on riboflavin requirements and of riboflavin intake on endurance were examined in 14 women, 50-67 y of age, who participated in a 10-wk, two-period crossover exercise study at two riboflavin intakes, 0.15 micrograms/kJ (0.6 micrograms/kcal) and 0.22 micrograms/kJ (0.9 micrograms/kcal). Subjects exercised 20-25 min/d, 6 d/wk, for 4-wk periods on a cycle ergometer at 75-85% of their maximal heart rate. Riboflavin status was assessed by measuring the erythrocyte glutathione reductase activity coefficient (EGRAC) and urinary riboflavin excretion. Physical performance was evaluated by using a walking treadmill test to determine maximal oxygen capacity (VO2max) and anaerobic threshold by gas exchange (ATGE). Exercise significantly affected riboflavin status as EGRAC increased (P less than 0.001) and riboflavin excretion decreased (P less than 0.01) in both groups. VO2max increased significantly with exercise (P less than 0.01). However, changes in VO2max (L/min) and ATGE with exercise training were not different in the two groups. Riboflavin requirements of older women increased with exercise training, but increased riboflavin intake did not enhance improvements in endurance.

In order to develop an obesity management program for teenagers, we compared obese and non-obese girls attending high schools in terms of their dietary practices related to snack consumption. Dietary records were collected for 7 days. No significant differences were found for the average daily energy intake between obese and non-obese girls. However, the highest energy intake was greater for obese girls while not much difference was found for the lowest amount of energy intake. Obese girls had significantly lower intakes in calcium (P < 0.01), vitamin A (P < 0.001) and folate (P < 0.01). Mean energy intake from snack (594.1 ± 312.1kcal) was significantly higher for obese girls than for non-obese girls (360.1 ± 173.1kcal) (P < 0.001). A significant, positive correlation was observed between energy intake from snack and total daily energy intake (r = 0.34 P < 0.01) only for obese girls. In case of dietary behaviors, obese adolescent girls consumed significantly greater number of items for snacks and fewer foods for regular meals compared to non-obese girls (P < 0.05). This study suggested that obesity management programs for adolescents should focus on providing strategies to reduce snack through enhancing balanced regular meals.

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