- Cutting ultra-processed foods improved weight, cholesterol and insulin sensitivity.
- Both meat-based and vegetarian diets delivered similar metabolic health benefits.
- Older adults ate fewer calories naturally when meals focused on whole foods.
We all want to live long lives, but what about living healthy lives? The concept of “healthspan” refers to the years we spend in good health, free from chronic disease. It’s a goal many of us share, and our metabolic health plays a role in achieving it. As we age, our cardiometabolic function, which includes things like blood sugar control and cholesterol levels, often declines.
A recent study published in Clinical Nutrition provides compelling evidence on how dietary changes can enhance healthspan.
How Was the Study Conducted?
Researchers at South Dakota State University explored how diet quality affects metabolic health among adults aged 65 and older. They designed an 18-week, randomized controlled trial where they provided all meals to the participants. This controlled feeding approach allowed them to precisely track what everyone ate.
The 36 participants were split into two groups, each following one diet for eight weeks before switching to the other. Both diets were designed to be aligned with the previous Dietary Guidelines for Americans, 2020-2025, but they differed in their primary protein source:
- An omnivorous diet featuring minimally processed lean pork as the main source of animal protein. This diet was also designed to be plant-forward, with plenty of vegetables, fruits, whole grains, and dairy products like yogurt and milk, plus eggs. No other meats or poultry were included during this phase, and all dishes avoided added preservatives or artificial ingredients.
- A lacto-ovo vegetarian diet centered on lentils as the primary protein source. This pattern included beans, chickpeas, split peas and a variety of lentil-based dishes, complemented by dairy (like cottage cheese, strained (Greek-style) yogurt or milk), eggs, vegetables, fruit and whole grains. Like the omnivorous diet, all ingredients were minimally processed and meals were prepared without artificial additives.
The most important part of the study was that both diets drastically reduced the amount of ultra-processed foods (UPFs) the average participant consumed. At the start of the study, nearly 50% of the participants’ daily calories came from UPFs. During the intervention, this was reduced to just 11 to 14%. Throughout the study, researchers tracked key health markers like body weight, body fat, blood sugar, cholesterol and levels of certain hormones that regulate metabolism.
What Did the Study Find?
The results were surprisingly consistent across both diet groups. Despite not being told to restrict calories, participants naturally ate fewer calories and experienced health improvements. This suggests the benefits weren’t about choosing meat or lentils, but rather about ditching many ultra-processed foods in favor of whole, minimally processed foods.
Here are some of the key findings:
- Weight loss: Participants lost an average of 3.8 to 4.4 kilograms (about 8 to 10 pounds) during the study without intentionally dieting.
- Reduced fat: Visceral fat, which is the harmful fat surrounding organs, decreased by about 13%. Total body fat also declined significantly.
- Improved insulin sensitivity: Insulin resistance, a precursor to type 2 diabetes, dropped by 24%. This means participants’ bodies became much better at managing blood sugar.
- Better cholesterol levels: Participants saw significant reductions in total cholesterol and LDL (“bad”) cholesterol—those reductions can lower the risk of heart disease.
- Favorable hormonal shifts: The study noted changes in two key metabolic hormones. FGF21, a hormone linked to energy regulation and longevity, increased. At the same time, leptin, the hormone that signals fullness and is tied to body fat, decreased.
Limitations
While these results are exciting, it’s important to consider a few limitations. First, the study included only 36 participants (a relatively small sample size), making it harder to draw broad conclusions for all older adults. In addition, most participants were white, college-educated, and lived in rural areas in the Midwest, which limits how well the findings might apply to a more diverse or urban population. Another limitation is the study’s relatively short duration of 18 weeks, so we don’t know if these improvements would be sustained over several years. Larger, longer, and more diverse studies are needed to confirm these findings and understand their long-term impact.
How Does This Apply to Real Life?
This study’s findings show that you may not need to follow a rigid, restrictive diet to improve your health. The key is to focus on diet quality. Ultra-processed foods, like packaged snacks, sugar-sweetened drinks, fast food and ready-to-eat meals, are engineered to be delicious but often lack essential nutrients while being a source of added sugar, unhealthy fats and excessive amounts of salt.
By replacing these ultra-processed items with whole or minimally processed foods, you can make a major impact on your well-being. The study also shows that you can achieve these benefits with different dietary patterns, whether you eat meat or prefer a vegetarian lifestyle. The common thread is the emphasis on whole foods, which can help you get the nutrients you need every day.
To reduce UPFs in your diet, you can swap your ultra-processed snacks for a handful of nuts, a piece of fruit, or some strained (Greek-style) yogurt. You can also cook more at home: preparing your own meals gives you complete control over the ingredients.
Our Expert Take
This recent study published in Clinical Nutrition explored the effects of two nutrient-rich diets that both focused on reducing ultra-processed food intake. Over 18 weeks, participants experienced meaningful benefits, including weight loss, reduced body fat, improved cholesterol levels and enhanced insulin sensitivity, regardless of whether their protein source was meat or lentils. These improvements appeared to be driven by a shift to minimally processed foods and cutting out packaged, nutrient-poor options.
The research delivers a clear and encouraging message: improving your metabolic health and extending your healthspan is within reach. While diet is just one piece of the longevity puzzle, it plays a vital role. By focusing on a diet rich in whole, nutrient-dense foods and reducing ultra-processed products, you can support your body’s ability to function at its best.