ENERGY RESTRICTION DECREASES NUMBER OF CIRCULATING NATURAL-KILLER-CELLS AND SERUM LEVELS OF IMMUNOGLOBULINS IN OVERWEIGHT WOMEN

We examined the effects of energy restriction on immune response and a lso compared the effects of low fat (LF, 18.6 E%) and high fat (HF, 40 .7 E%) diets during energy restriction on immunological parameters. Te n overweight women were fed the HF diet for 42 days (PI) to maintain t heir body weights. For the next 84 days (P2), the energy intake was re duced to 50% of the intake during P1 for all the women, five of them w ere fed the HF diet and the other five the LF diet. For the last 35 da ys of the study (P3), subjects remained on their respective diets, but the energy intake was increased to maintain BW to the level reached a t the end of energy restriction. Serum concentrations of IgG, IgA, IgM , C3 and C4, numbers of lymphocytes and their subsets, blastogenesis o f peripheral blood mononuclear cells cultured with phytohemagglutinin, concanavalin A and protein A were determined several times during the study. Delayed hypersensitivity skin (DHS) response to seven recall a ntigens was determined towards the end of each study period. None of t he parameters studied were different between the HF and LF dietary gro ups. During energy restriction the subjects lost an average of 7 kg in the LF group and 9 kg in the HF group. Energy restriction caused a si gnificant (P < 0.005) decrease in the serum concentration of IgG, IgA, C3, and the number of circulating natural killer (NK) cells. An incre ase in energy intake during P3 reversed some of the decreases caused b y energy restriction, but the levels did not return to pre-restriction levels during these 35 days of refeeding adequate dietary energy. The numbers of circulating lymphocytes and their subsets with the excepti on of NK cells, serum levels of IgM and C4, and the DHS response monit ored 48 h after the application of antigens were not affected by energ y restriction. Health status of the women in our study did not seem to be compromised; however, it could be compromised under more drastic r estrictions or with moderate restrictions in high risk subjects.