Mild weight loss reduces inflammatory cytokines, leukocyte count, and oxidative stress in overweight and moderately obese participants treated for 3 years with dietary modification

Obesity-induced oxidative stress and inflammation are involved in the pathogenesis of cardiovascular disease. We investigated whether diet-induced, long-term, mild weight loss improved proinflammatory cytokine levels, leukocyte count, and oxidative stress. Overweight/obese participants (25 ≤ body mass index < 34 kg/m², N = 122, 30-59 years) joined a 3-year-long clinical intervention involving daily 100-kcal calorie deficits. Successful weight loss was defined as a reduction in initial body weight equal to 2 kg after the clinical intervention period. Body weight in the successful mild weight loss group (SWL, n = 50) changed 5.4% (-4.16 ± 0.31 kg) compared to 0.05 ± 0.14 kg in the unsuccessful weight loss group (n = 49). After 3 years, SWL participants exhibited significantly reduced insulin, triglycerides, total and low-density lipoprotein cholesterol, free fatty acids, and leukocyte count (P = .030). Furthermore, in the SWL group, serum interleukin (IL)-1β, IL-6, and urinary 8-epi-prostaglandin (PG)F_2α were significantly reduced (45%, 30%, and 14%, respectively). In contrast, the unsuccessful weight loss group exhibited significant increases in percentage of body fat, waist circumference, oxidized low-density lipoprotein, and tumor necrosis factor-α, as well as a significant decrease in high-density lipoprotein cholesterol. After adjusting for baseline values, the 2 groups demonstrated significantly different percentage of body fat, waist circumference, leukocyte count (P = .018), insulin, IL-6 (P = .031), IL-1β (P < .001), and tumor necrosis factor-α (P < .001), as well as urinary 8-epi-PGF_2α (P = .036). A positive correlation existed between IL-1β and urinary 8-epi-PGF_2α (r = 0.435, P < .001) and between changes in IL-6 and urinary 8-epi-PGF_2α (r = 0.393, P < .001). Long-term mild weight loss reduces inflammatory cytokine levels, leukocyte counts, and oxidative stress and may reverse the elevated oxidative stress induced by inflammatory mediators in the overweight and obese.