To investigate the effects of parasitism and
caloric restriction on morphology (body composition, organ mass) and physiology (resting metabolism, intestinal
glucose transport capacity), we gave laboratory mice intestinal parasites (Heligmosomoides polygyrus, Nematoda), 30%
caloric restriction, or both. Calorically restricted mice had smaller body mass, enhanced
glucose transport capacity, and lower resting metabolism than ad libitum-fed mice. Parasitized mice maintained body mass, had diminished intestinal
glucose transport capacity, and greater resting metabolism than unparasitized mice. Parasitized, calorically restricted mice had smaller organ masses than parasitized, ad libitum-fed mice and did not increase their
glucose uptake rate as much as unparasitized, calorically restricted mice. There was a significant interaction between
caloric restriction and parasite status for morphological variables but not for physiological variables. Knowing the types of phenotypic changes that occur with simultaneous parasitism and
caloric restriction will provide insight into understanding human
helminthiasis in food-restricted communities and also how wild animals cope with environments where parasitism and seasonal food restriction are common.