Reviewed by Dietitian Jessica Ball, MS, RD
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Key points
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Cutting out ultra-processed foods improved weight, cholesterol and insulin sensitivity.
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Both meat-based and vegetarian diets provided similar metabolic health benefits.
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Older adults naturally ate fewer calories when meals focused on whole foods.
We all want to live a long life, but what about living healthy do you live? The concept of “span of health” refers to the years we spend in good health without chronic disease. It’s a goal many of us share, and our metabolic health plays an important role in achieving it. As we age, our cardiometabolic function, which includes things like controlling blood sugar and cholesterol levels, often declines.
A recent study published in Clinical nutrition provides compelling evidence of how dietary changes can improve longevity.
How was the study conducted?
Researchers at South Dakota State University explored how diet quality affects metabolic health among adults age 65 and older. They designed an 18-week randomized controlled trial in which they provided participants with all meals. This controlled feeding approach allowed them to track exactly what everyone was eating.
The 36 participants were divided into two groups, each following one diet for eight weeks before switching to the other. Both diets were designed to align with the previous Dietary Guidelines for Americans, 2020-2025, but differ in their primary protein source:
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A omnivorous diet featuring lightly processed pork as the main source of animal protein. This diet was also designed to be plant-based, with plenty of vegetables, fruits, whole grains, and dairy products like yogurt and milk, plus eggs. No other meat or poultry was included in this phase, and all dishes avoided the addition of preservatives or artificial ingredients.
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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 foods, supplemented with dairy (such as cottage cheese, yogurt, or strained (Greek-style) milk), eggs, vegetables, fruits, 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 (UPF) consumed by the average participant. At the start of the study, almost 50% of participants’ daily calories came from UPF. During the intervention, this was reduced to only 11 to 14%. During the study, the researchers tracked key health markers such as 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 improvements in health. This suggests that the benefits were not related to the choice of meat or lentils, but rather to giving up many ultra-processed foods in favor of whole, minimally processed foods.
Here are some of the main findings:
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Weight loss: Participants lost an average of 3.8 to 4.4 kilograms (about 8 to 10 pounds) during the study without dieting on purpose.
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Reduced Fat: Visceral fat, which is the harmful fat around your organs, decreased by about 13%. Total body fat also decreased significantly.
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Improved insulin sensitivity: Insulin resistance, a precursor to type 2 diabetes, decreased by 24%. This means that the participants’ bodies became much better at managing blood sugar.
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Better cholesterol levels: Participants saw significant reductions in total cholesterol and LDL (“bad”) cholesterol—these reductions can reduce the risk of heart disease.
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Favorable hormonal changes: The study observed 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 linked to body fat, decreased.
limitation
Although these results are interesting, it is important to consider several limitations. First, the study included only 36 participants (a relatively small sample size), making it more difficult to draw general conclusions for all older adults. In addition, most participants were white, college educated, and lived in rural areas of the Midwest, which limits how well the findings might apply to a more diverse or urban population. Another limitation is the relatively short duration of the study, 18 weeks, so we do not know whether these improvements will 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 in real life?
The findings of this study show that you may not need to follow a rigid, restrictive diet to improve your health. The key is to focus on your diet quality. Ultra-processed foods such as packaged snacks, sugar-sweetened beverages, fast foods, and ready-to-eat meals are designed 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 have a major impact on your well-being. The study also shows that you can get these benefits with different eating patterns, whether you eat meat or prefer a vegetarian lifestyle. The common thread is an emphasis on whole foods, which can help you get the nutrients you need every day.
To reduce UPFs in your diet, you can swap 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
This recent study published in Clinical nutrition explored the effects of two nutrient-dense diets that both focused on reducing the intake of ultra-processed foods. Over 18 weeks, participants experienced significant benefits, including weight loss, reduced body fat, improved cholesterol levels and increased insulin sensitivity, regardless of whether their protein source was meat or lentils. These improvements appear to be driven by a shift to minimally processed foods and the elimination of packaged, nutrient-poor options.
The research provides a clear and encouraging message: improving metabolic health and extending health span is within reach. While diet is only one piece of the longevity puzzle, it plays a vital role. By focusing on a diet rich in whole, nutrient-dense foods and cutting back on ultra-processed foods, you can support your body’s ability to function at its best.
Read the original article on EatingWell