4. Discussion
obesity, TNsnack, overweight, overweight or obesity, metabolic syndrome, TG
OBESITY, INSULIN RESISTANCE, ADIPOSITY, METABOLIC SYNDROME, DYSLIPIDEMIA
This randomized parallel design eucaloric diet intervention study had several key findings. First, daily consumption of tree nuts as between-meal snacks significantly reduced total metabolic syndrome risk score in young adults, most of whom met BMI criteria for overweight or obesity and had at least one METSx risk factor at baseline. Although this is the first trial comparing consumption of tree nuts as snacks versus typical carbohydrate snacks in young adults, the reduction in MetSx score is consistent with NHANES data showing lower prevalence of MetSx in tree nut consumers [Evidence from nutrient analysis studies suggests that tree nuts offer substantial protective cardiometabolic health benefits due to their compositional characteristics [Despite being a plant based food, the high energy density (kcal/g) of tree nuts, due to dietary fat content, has raised concern for a potential weight gaining effect—especially in the current environment where young adults (20–39 years) are the age group at greatest risk for developing overweight and obesity [Along with the rise in the prevalence of overweight and obesity in young adults, data from NHANES shows the largest increase in waist circumference, a proxy for abdominal adiposity, has been occurring in the young adult age group [Another mechanism by which increased tree nut consumption could exert beneficial metabolic health effects and reduce MetSx risk is by altering lipid metabolism and reducing dyslipidemia. A systematic review and meta-analysis of 10 randomized controlled trials in persons with overweight or obesity showed significant reductions in serum LDL-cholesterol and triglycerides (TG) levels [A meta-analysis of the effects of tree nuts on glycemic indexes showed that tree nut consumption yields a modest reduction in fasting insulin levels and insulin resistance (based on HOMA-IR score), but does not change fasting glucose levels [Strengths of this study include the randomized parallel arm design and the application of a pragmatic real-world dietary snack intervention, especially at a time when the portion size and frequency of snack consumption contributes to almost one-fourth of daily caloric intake in young and middle-aged adults. Additionally, effects of tree nuts as snacks were investigated without caloric restriction, which would mask any beneficial direct effects of tree nuts. Thirdly, the intervention and support participants received from registered dietitians was similar for TNsnack and CHOsnack groups. A limitation of the study is the relatively small sample size per group which makes data analysis statistically underpowered to detect differences between groups for variables that have large variability. Thus, several data trends observed require further investigation with larger samples. Secondly, the intervention period of 16 weeks is likely too short a duration to detect changes in CT-determined morphometrics. Finally, it is well-recognized that diet assessment via self-reporting, despite using validated methodology, is susceptible to under or over-reporting bias.