Average Dietary Energy Intake does not Increase as BMI Increased in the National Health and Nutrition Examination Survey Data of Korea

Although the idea that obese people consume higher calorie diets is widely accepted, many dietary surveys have shown that obese people do NOT consume larger amounts of energy. We had an opportunity to study the relationship between calorie intake and obesity in Korea from the data contained in the '98 National Health and Nutrition Examination Survey of Korea. The survey was executed nationwide for two months - from Nov. 1 to Dec.30 in 1998. The survey included 10,876 (aged >10 years) subjects of whom 9,771 underwent health examinations. Surveyors visited each household and checked health status, measured anthropometry and blood pressures, collected blood and urine samples, and interviewed from the health questionnaires. Well-trained dietitians evaluated the food consumption of 11,525 subjects over the age of 1 year with the 24-hour recall method. The number of subjects from whom a complete health examination and food consumption information was obtained was 8,004. Subjects were classified by BMI (< 20, 20-22, 22-24, 24-26, 26-28, 28 $\leq$) and into newly diagnosed patients with DM (FBS $\geq$ 126 mg/㎗), hypertension (SBP $\geq$ 140 mmHg or DBP $\geq$ 90 mmHg) and hyperlipidemia (Total cholesterol $\geq$ 220 mg/㎗ or TG $\geq$ 200 mg/㎗). Our main results were as following：1) their average energy intake was 2,029.6 $\pm$ 908.5 ㎉ and BMI is 22.6 $\pm$ 3.4 kg/$m^2$；2) a comparison of nutrient intakes by BMI level did not show a significant difference of energy intake even though BMI increased (BMI, < 20： 1,999 ㎉ ∼ 28 $\leq$： 2,028 ㎉)；and 3) Even in newly diagnosed patients with diabetes, hypertension or hyperlipidemia, their energy consumption was not significantly increased as BMI increased (from BMI 20). There are several possible explanations for these results：1) Reduced physical activity caused the weight of obese people to increase even with the same energy intake；2) people underreported their energy consumption；or, people intentionally reduced their energy consumption due to self-image regarding their obesity. We might also hypothesize that there is a metabolic problem conceiving obese people, because calorie intake was not higher in obese people than in non-obese people in Korea. Further research is necessary for re-evaluating these current conclusions.