Dietary fat affects weight loss and adiposity during energy restriction in rats.

This study examined the effect of dietary fat during food restriction on weight loss, body composition, and adipose tissue lipoprotein lipase activity (ATLPL). Rats previously fed a high-fat diet were divided into four groups. One group served as baseline controls. The other three groups were fed diets of 12%, 28%, or 45% fat, restricted (R) in amounts to equal 75% of their previous ad libitum energy intake. After 10 wk, body weight loss and reduction of adiposity were significantly less in the 45%-R group compared with the 12%-R group (weight P < 0.05; adiposity P < 0.01). Rats fed restricted amounts of the high-fat diet (45%-R group) retained adiposity equivalent to baseline control rats. ATLPL activity was increased in the 45%-R group compared with baseline control rats. Further studies are needed in humans, but these results suggest that body composition will not be normalized with reduction of energy intake unless dietary fat is also reduced.