Energy efficiency of fat could be higher than what we currently recognize Lee, Jongsam (Ph.D.) Research Center for Exercise and Sports Sciences, Daegu University

The characters of FAT (Forbes et al., 1945) The nutrient of maximum energy value Palatability & “staying quality” to diets A carrier of fat-soluble Vit. (i.e., A, D, E, & K) Provides the essential fatty acid (i.e., linoleic [18:2] & linolenic acids [18:3] ) The composition of tissue lipids Insulates, supports and cushions vital organs Nutritive reserve for energy as needed Diminishes the energy expense of utilization of the nutrients with which it is associated

Does fat contain more physiological energy than CHO & protein in our bodies? Fat contain 2.25 times more metabolizable energy values than CHO & protein (9 kcal vs. 4 kcal)?

Protein contains average 16 percent of nitrogen (16.0) (17.5) (16.7) (16.0) (17.7) (17.2) (% of N.)

Non-oxidized energy material in the urine For every gram of nitrogen in the urine, there is non-oxidized material sufficient to yield 7.9 calories of energy For every 6.25 grams of protein consumed, therefore, there would be 7.9 calories of energy in the non-oxidized materials of the urine, or ~1.25 calories per gram (7.9 ÷ 6.25 = 1.26)

Propor- tion of total nutrients’ actual

(69.8 kcal∙d -1 ) (62.1 kcal∙d -1 )

Diets were contained 2, 5, 10, & 30% of fat, and provided isocaloric by compensating adjustment of CHO contents g gg g

To determine the energy expense of utilization (specific dynamic effect) of complete diets as affected by fat contents Using the open-circuit, respiratory quotient method of Haldane The diets contained 2, 5, 10, and 30% of fat, and fed as to supply identical quantities of energy, protein, and vitamins

The ME of corn oil for the chick is 8.8 kcal·g -1 (Oscai, 1982; Am J Physiol. 242) The apparent values for corn oil so calculated In Exp 1 were 9.4kcal·g -1 (20% corn oil + 100% EI) 11.0kcal·g -1 (20% corn oil + 75% EI) 10.9kcal·g -1 (20% corn oil + 50% EI) In Exp 2 were 10.9 kcal·g -1 (10% corn oil + 75% EI) 12.1 kcal·g -1 (20% corn oil + 75% EI) These values are 107 to 136% of the known ME of corn oil, and have a mean of 124%

Fat(spry) supplement amount(g) x 2.25 times = sucrose supplement amount(g)

4 Corn oil

Each increment of 100kcal in food intake resulted in a gain of 55 kcal in the obese (fa/fa) rats compared to 32 and 33kcal for the Charles River and Zucker lean(fa/?) rats Equal increments in food intake produced larger gains in total body energy, mainly fat, in the obese rats than in the Charles River or the Zucker lean rats

O 2 consumption was significantly reduced in genetically obese mice when compared to their lean littermates When the lean littermates became obese following hypothalamic lesions, they consumed significantly more O 2 than their genetically obese siblings

Marshall & Mayer (1954) Am. J. Physiol. 178: The storage of excess energy in the form of fat in obese animals results from Hypoactivity Hyperphagia Decreased energy expenditure Increased efficiency of food utilization

The metabolizable energy requirement for maintenance of lean and fat rats at 200 g would be 29.9 and 22.9 kcal The efficiency of utilization of metabolizable energy for growth, and for lean and fat rats

298.8 (68.8 vs kcal) (69.8 vs kcal) (60.9 vs kcal) (59.0 vs kcal) (58.1 vs kcal) vs kJ∙d -1 (69.1 vs kcal∙d -1 ) ↓16.5% vs. ↓1.7% vs kJ∙d -1 (59.3 vs kcal∙d -1 )

298.8 (69.8 vs kcal∙d -1 ) ↓12.4% vs. ↑2.9% (62.1 vs kcal∙d -1 )

Comparison of calory intake when either Atwater & Bryand’s value (9.0Cal·g -1 ) or Donato & Hegsted’s value (11.1Cal·g -1 ) was applied MaleFemale 2,500kcal∙d -1 Total Calory Intake 2,000kcal∙d -1 kcalgramkcalgram 1, CHO (55E%)1, * FAT (30E%) * ** ** Protein (15E%)30075 CHO, carbohydrate; FAT, fat. * 9.0kcal∙g -1 was adopted; ** 11.1kcal∙g -1 was adopted

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