Ultra-processed foods cause obesity and metabolic risks

Find out how ultra-processed foods promote obesity and metabolic risk, and why adopting a Mediterranean diet can help turn the tide on this growing health problem.

study: The close relationship between ultra-processed foods and obesity among adults in southern Italy. Image credit: Rinma Bondarenko / Shutterstock

In a recent study published in the journal nutrientsa group of Italian researchers investigated the relationship between ultra-processed food (UPF) consumption, obesity, and obesity measurements among adults in southern Italy.

background

Obesity is a global public health challenge, and food processing plays a key role in its rise. Modern food systems are shifting diets toward energy-dense UPFs that are highly palatable, low in nutritional value, and rich in calories. UPFs identified by the NOVA classification include snacks, soft drinks, and processed meats, which are associated with increased obesity rates. Although research suggests a strong association between UPF intake and obesity, limitations of observational studies, including reliance on survey tools not designed to assess food processing, warrant further research. It is necessary. These studies often rely on simplistic measures such as body mass index (BMI), highlighting the need for more robust methods to better understand health effects.

About research

The study was carried out at the outpatient clinic of the University of Naples Federico II IP “Dietary Therapy in Transplantation, Renal Failure and Chronic Pathology”. Data was collected from 175 participants aged 18-65 with a BMI of 30 kg/m² or more recruited from October to December 2021. Participants were stratified into three groups based on BMI: Class I obesity (BMI 30-34.9 kg/m²), Class I obesity II obesity (BMI 35-39.9 kg/m²), and Class III obesity (BMI 35-39.9 kg/m²). BMI ≥40) kg/m2). Exclusion criteria included bedridden status, pregnancy, cancer, dementia, depression, breastfeeding, diabetes, and neurological disorders.

Anthropometric measurements such as weight, height, and waist circumference were collected according to a standardized protocol. Body composition was assessed using bioelectrical impedance analysis, and subjects complied with pre-measurement conditions including fasting, avoidance of caffeine and physical activity. Additionally, biochemical parameters such as triglycerides, HDL-cholesterol, and triglyceride-to-HDL ratio were evaluated as markers of insulin resistance. Blood pressure was measured according to European Society of Cardiology (ESC) guidelines.

For nutritional assessment, we used PREvención con DIetaMEDiterránea (PREDIMED) and NOVA Food Frequency Questionnaires (NFFQ) to assess adherence to the Mediterranean diet and UPF intake. Obesity was analyzed using indicators such as waist-to-height ratio (WHtR), lipid accumulation product (LAP), visceral adiposity index (VAI), and cardiometabolic index (CMI). Statistical analysis was performed using SPSS, and significance was set at p < 0.05.

Research results

A total of 175 participants (36% male, mean age 43.3 ± 12.6 years, BMI 42 (95% CI: 37-47)) were analyzed to assess dietary habits in relation to BMI. Most participants were married and attending high school, and there were no statistically significant differences in sociodemographic characteristics, physical activity, or education level between BMI groups. However, individuals with higher BMI values ​​were more likely to reside in small and medium-sized cities compared to those in the lowest BMI group who lived primarily in metropolitan areas (p < 0.05).

UPF consumption significantly increased with BMI in both percentage and absolute values. UPF consumption accounted for 18.2% (95% CI: 16.7-23.5) in group 1 compared to 26.2% (95% CI: 26.6-32.5) in group 3 (p < 0.01). Daily UPF intake increased from 274.2 g/day (95% CI: 241.5-495.5) in group 1 to 526.2 g/day (95% CI: 575.9-802.8) in group 3 (p < 0.001 ). Soft drinks emerged as the main culprit, with consumption more than doubling in group 3 compared to group 1 (p < 0.01). The higher BMI group also showed increased intake of sweets, chips, sausages, salty snacks, ice cream, and nuggets (p < 0.05 to p < 0.001); MPF intake decreased significantly (p < 0.001).

Adherence to the Mediterranean diet (MD) was low across all BMI groups, with a significant decline observed as BMI increased. Group 3 participants had a PREDIMED score of 5 (95% CI: 4.8 to 5.3), reflecting lower MD adherence compared to groups 1 and 2 (p < 0.005).

Further analysis divided participants into tertiles based on UPF consumption and revealed a significant trend for younger participants in the highest UPF tertile (p < 0.05). Increased UPF consumption was associated with increased body mass index, including WHtR, VAI, LAP, CMI, and waist triglyceride index (WTI) (p < 0.001). WHtR increased from 0.6 (95% CI: 0.6-0.7) at T1 to 0.7 (95% CI: 0.7-0.8) at T3. VAI and LAP values ​​were significantly increased, with the latter increasing from 80.4 (95% CI: 65.9-91.4) at T1 to 113.6 (95% CI: 95.3-129) at T3. These findings highlight a clear link between increased UPF intake and obesity-related adverse outcomes.

conclusion

In summary, this study revealed that there was a positive association between UPF intake and obesity, and increased UPF intake was associated with higher body mass index and lower MD adherence. The main driver was soft drinks, whose consumption increased with BMI, followed by processed snacks and ready-to-eat foods. The high palatability, high energy density, and additives of UPF can promote overeating, visceral fat accumulation, and metabolic disorders. Furthermore, this study also highlights the higher cardiometabolic risk observed in participants with elevated WHtR and VAI indices. Elevated indices such as WHtR and VAI in high UPF consumers highlight increased cardiometabolic risk.

The authors point out limitations such as the retrospective nature of the study and the lack of assessment of stress levels and sleep quality, which may influence obesity outcomes. These findings highlight the need for public health strategies that promote traditional diets such as the Mediterranean diet and limit UPF intake as part of obesity prevention.