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FIGURE 12-1 Schematic representation of interactions between appetite and components of energy balance. SOURCE: J. A. LeBlanc (Unpublished data, Laval University, Quebec City, 1993).
COMPONENTS OF ENERGY EXPENDITURE IN THE COLD
Basal Metabolic Rate
When the total energy expenditure for a typical subject is 2,750 kcal/d, approximately 60 percent of this total energy is due to basal metabolic rate (BMR) (1,500 kcal). Some years ago it was reported that Eskimos had higher BMR than Caucasians. It was suggested that this might be due to an increased thyroid activity induced by cold (Rodahl, 1952a, b). Subsequent work disproved this hypothesis. It was shown that the higher BMR of Eskimos was due to the high protein content of their diet. When Eskimos were made to eat a mixed diet comparable to the one consumed by Caucasian subjects, BMRs were the same for the two groups (Rodahl, 1952a, 1952b, 1955).
Thermogenic Effect of Feeding
The digestion, absorption, and storage of ingested nutrients require energy. The level of expenditure, known as the thermogenic effect of feeding (TEF), is different depending on whether carbohydrates, proteins, or lipids are consumed (Unpublished data, J. A. LeBlanc, Laval University, Quebec City, 1992) (Figure 12-2). For a comparable calorie intake, the TEF is small for fat,
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