This Everyday Habit May May Slow “Metabolic Aging,” Study Suggests
If you've spent any time in health circles lately, you've probably heard the phrase "biological age" thrown around alongside expensive testing panels, longevity supplements, and highly specific eating protocols. But a recent study1 suggests the most meaningful lever for metabolic health over time may be far more straightforward. It's the overall quality of your diet on a daily basis.
About the study
The objective of this study was to examine whether higher diet quality is associated with healthier markers of metabolic aging and whether systemic inflammation may help explain that relationship. Researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES), a large, ongoing U.S. health study, looking at 15,314 adults aged 20 and older across a 15-year period.
To see whether their findings held up in a different population, they also looked at an independent group of 833 adults who had routine health checkups in Shandong, China, between 2024 and 2025.
Diet quality was measured using the Healthy Eating Index-2015 (HEI-2015), a validated scoring tool that measures how closely a person's eating habits align with the U.S. Dietary Guidelines. Higher scores reflect more fiber, unsaturated fats, vitamins, and minerals, and less refined carbohydrates, trans fats, and added sugar.
The researchers then compared participants' diet quality scores with two markers linked to metabolic aging:
- HOMA-IR, a measure of insulin resistance
- AIP (atherogenic index of plasma), a marker associated with cardiovascular risk and lipid metabolism
They also examined a marker of systemic inflammation called the Systemic Immune-Inflammation Index (SII).
Better diet quality was linked to healthier metabolic markers
The results showed that people with higher diet quality scores tended to have lower levels of insulin resistance and more favorable lipid-related markers (like cholesterol). These associations appeared in both the U.S. and Chinese cohorts, suggesting the relationship was reproducible across two distinct populations.
The researchers also found that the relationship was largely linear, meaning that progressively better diet quality was associated with progressively healthier metabolic markers throughout the observed range.
While the association with lipid metabolism was relatively modest, the findings support a broader body of research linking overall dietary patterns (not just individual foods or nutrients) to cardiometabolic health.
Inflammation may be part of the connection
One of the more interesting findings was that systemic inflammation appeared to partially explain the relationship between diet quality and metabolic aging markers.
Specifically, the SII accounted for a small but meaningful portion of the association between healthier diets and better metabolic outcomes.
This aligns with what researchers already know about inflammation's role in metabolic health. Chronic low-grade inflammation has been linked to insulin resistance, impaired glucose control, and disruptions in lipid metabolism.
Researchers note several ways higher-quality diets may help support a healthier inflammatory environment, including:
- Providing more fiber that supports beneficial gut bacteria and short-chain fatty acid production
- Delivering polyphenols and other plant compounds with anti-inflammatory properties
- Increasing intake of omega-3 fats, which may help regulate inflammatory signaling
- Reducing oxidative stress throughout the body
That said, inflammation likely represents just one piece of a much larger puzzle.
What this study can & can't tell us
The researchers are transparent about the study's limits. Because it's cross-sectional, it cannot establish that eating better causes improvements in these markers, only that the two tend to go together.
The HEI-2015 was developed based on U.S. Dietary Guidelines and may not fully capture the nuances of traditional Chinese dietary patterns, which limits how directly the two groups can be compared.
The Chinese hospital group was also a convenience sample of people seeking routine health exams, not a representative sample of the broader population.
Dietary data in both groups relied on self-reported recall, which comes with the usual memory limitations. And while SII is a useful composite marker for inflammation, it doesn't capture the full picture of how the immune system interacts with metabolism.
What higher diet quality actually looks like day to day
So what does this mean for your diet? Prioritize the foundational components of healthy eating.
- More whole grains: Oats, brown rice, quinoa, and whole wheat bread over refined white flour products
- More vegetables and legumes: A wide variety of colorful produce, including leafy greens, cruciferous vegetables, and fiber-rich beans and lentils
- More fruit: Whole fruit over juice, prioritizing variety
- More lean protein and seafood: Fish (especially fatty fish like salmon and sardines), poultry, eggs, and plant-based proteins like tofu and tempeh
- More healthy fats: Olive oil, avocado, nuts, seeds, and omega-3-rich foods like walnuts and chia seeds
- Less added sugar: Fewer sweetened beverages, packaged snacks, and ultra-processed foods
- Less refined carbohydrates and trans fats: Fewer white bread products, fried foods, and highly processed packaged items
It's also worth noting the polyphenol content of this type of diet. Foods like berries, olive oil, green tea, dark chocolate, herbs, and colorful produce are rich in plant compounds that have been associated with anti-inflammatory and metabolic benefits in prior research.
The takeaway
While the findings of this study may sound intuitive (yes, eating healthier supports metabolic health and improves inflammation), it's findings reinforce what that healthy eating pattern includes—across two distinct populations. And it adds to the research showing that the cumulative effect of whole-food eating patterns over time, rather than any single food.