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animal fats resulting in the promotion of body fat accumulation.
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Diet-induced thermogenesis is lower in rats fed a lard diet than in
those fed a high oleic acid safflower oil diet, a safflower oil diet or
a linseed oil diet.
Takeuchi H, Matsuo T, Tokuyama K, Shimomura Y, Suzuki M
J Nutr. 1995 Apr ; 125(4): 920-5

The objectives of the present study were to examine the effects of
dietary fats differing in fatty acid composition on diet-induced
thermogenesis, sympathetic activity in brown adipose tissue and body
fat accumulation in rats. Rats were meal-fed for 12 wk an isoenergetic
diet based on lard, high oleic acid safflower oil, safflower oil or
linseed oil, and norepinephrine turnover rates in brown adipose tissue
were then estimated. Whole-body oxygen consumption after the meal
indicated that diet-induced thermogenesis was significantly lower in
rats fed the lard diet than in those fed the other diets. The
norepinephrine turnover rate in the interscapular brown adipose tissue
was also significantly lower in the lard diet group than in the other
diet groups. The carcass fat content was significantly higher in the
lard diet group than in the other diet groups, whereas the abdominal
adipose tissue weights were the same in all diet groups. These results
suggest that the intake of animal fats rich in saturated fatty acids,
compared with the intake of vegetable oils rich in monounsaturated or
polyunsaturated fatty acids, decreases diet-induced thermogenesis by a
decline of sympathetic activity in brown adipose tissue, resulting in
the promotion of body fat accumulation.