Immune response to obesity and moderate weight loss.

OBJECTIVE

To study the effect of moderate energy restriction (4.19-5.44 MJ or 1200-1300 kcal per day) in obese females on a variety of both innate and adaptive immune function measures including mitogen-stimulated lymphocyte proliferative response, and monocyte and granulocyte phagocytosis and oxidative burst. Obese and nonobese subjects were also compared at baseline.

DESIGN

Measurement of body composition and immune function was conducted in all subjects before and after a 12-week diet intervention period for the obese subjects, with data analyzed using a two (obese and nonobese groups) x two (pre- and post-study) repeated measures design.

SUBJECTS

Thirteen obese (42.3 +/- 0.8% body fat) and 10 nonobese (21.2 +/- 1.0%) healthy, normoglycemic, premenopausal females.

MEASUREMENTS

Pre- and post-study body composition, nutrient intake, and immune function, with the reducing diet monitored through weekly random 24-h dietary recalls.

RESULTS

Data from this study indicate that despite large differences in body fat mass between the obese and nonobese groups, immune function, as measured in this study, was similar between groups. Weight loss, however, even though relatively moderate (9.9 +/- 1.4 kg), was associated with significant decreases relative to the nonobese in several measures of T, B, monocyte and granulocyte function.

CONCLUSION

These data do not support the contention that mild-to-moderate obesity is associated with alterations in immune function. The data are consistent, however, with the viewpoint that weight loss, even at a moderate rate, is associated with a decrease in the function of certain aspects of the immune system.