The impact of high- or low-fat cafeteria foods on nutrient intake and growth of rats consuming a diet containing 30% energy as fat

The objective of this study was to determine the impact of high-fat and low-fat cafeteria foods on energy intake and body composition of growing rats. Two sets of 30 male Sprague-Dawley rats weighing either 90 g or 280 g, were each divided into two groups of eight and two groups of seven animals, matched for average weight. All animals were offered a semi-purified diet containing 30% kJ fat. After ten days, initial body composition, carcass energy and serum lipids, insulin and glucose were determined in seven rats from each age group. Seven rats in each age group continued to receive the semi-purified diet ad libitum, eight received semi-purified diet plus one high-fat cafeteria food each day and eight received semi-purified diet plus one low-fat cafeteria food each day. After 38 days, body composition, efficiency of energy retention and serum lipids, insulin and glucose were determined. Food and energy intakes were greater for rats offered cafeteria foods compared with controls. Those given low-fat foods ate the greatest quantity of food but those fed high-fat foods had the highest energy intake. High-fat foods increased fat intake to approximately 43% of energy. Low-fat foods decreased fat intake to approximately 24% kJ. There was no effect of treatment on weight gain or lean body mass of either age group. Young rats fed low-fat cafeteria foods had less body fat than their controls. There was no significant increase in body fat content of rats fed high-fat cafeteria foods. Older animals fed high-fat foods had higher serum insulin and lower serum cholesterol than their controls. The results of this study suggest that replacing high-fat snack foods with low-fat or fat-free counterparts may reduce total fat and energy intake without changing rate of weight gain or deposition of lean tissue during growth.