Researchers looked at studies combining exercise and healthy eating for people with kidney disease who aren’t on dialysis yet. They found that combining both approaches helped people’s heart fitness improve, but didn’t clearly help kidney function itself. The review included five studies with 339 people total. While the results are promising, scientists say we need more research to be sure these combined treatments really work. This matters because kidney disease affects millions of people, and finding ways to slow it down could help them live healthier lives.

The Quick Take

  • What they studied: Whether combining exercise training with nutritional counseling helps people with chronic kidney disease better than doing just one or neither
  • Who participated: 339 adults across five different studies who had kidney disease (stages 3-5) but weren’t yet on dialysis treatment
  • Key finding: People who did both exercise and improved their diet showed better heart fitness (about 2.7 points better on a fitness test), but the studies didn’t show clear improvements in actual kidney function
  • What it means for you: If you have kidney disease, combining exercise with better nutrition may help your overall fitness and health, though it may not directly slow kidney damage. Talk to your doctor about what’s safe for your specific situation

The Research Details

Scientists searched medical databases for high-quality studies (called randomized controlled trials) that tested whether combining exercise and nutrition help kidney disease patients. They looked for studies published through September 2024 in English and Japanese. They only included studies where one group got both exercise and nutrition help, while other groups got just one or neither.

They found five studies that met their strict requirements, involving 339 people total. The researchers used special tools to check if each study was done well and fairly, looking for things like whether patients were randomly assigned to groups and whether results might be biased.

They then combined the results from these studies to see if patterns emerged. This approach is called a meta-analysis, and it’s like putting puzzle pieces together to see the bigger picture.

By combining results from multiple studies, researchers can see if findings are consistent and reliable. This approach is stronger than looking at one study alone because it reduces the chance that one study’s results were just luck. However, the researchers noted that the studies they found had some differences in how they were done, which makes the overall picture less clear.

The researchers found that while the studies were reasonably well-designed, there were some concerns: the number of studies was small (only five), the studies didn’t all measure things the same way, and some had potential biases. This means the results should be seen as helpful hints rather than definitive proof. More and better studies are needed to be confident about these findings.

What the Results Show

The main finding was that people who combined exercise with nutritional changes improved their heart fitness. Specifically, their peak oxygen uptake (a measure of how well your heart and lungs work during exercise) improved by about 2.7 points on the measurement scale. This improvement was statistically significant, meaning it’s unlikely to have happened by chance.

However, the combined approach did not show clear improvements in kidney function itself. The researchers measured kidney function using standard blood and urine tests, and these didn’t improve significantly in the combined treatment groups compared to control groups.

The researchers couldn’t draw strong conclusions about other important outcomes like survival rates, whether people needed to start dialysis, muscle mass changes, or quality of life improvements. This was because too few studies measured these outcomes, making it impossible to combine the results reliably.

While not statistically combined, individual studies suggested that the combined approach may help with muscle strength and overall physical function, though the evidence wasn’t strong enough to confirm. Some studies also hinted at quality of life improvements, but again, the evidence was limited. The researchers noted that none of the studies showed harmful effects from the combined intervention.

This review builds on earlier research showing that exercise alone and nutrition changes alone can each help kidney disease patients. The new finding suggests that combining both approaches may be better for heart fitness than doing either one alone. However, the lack of clear kidney function improvement was somewhat surprising and suggests that while these interventions help overall health, they may not directly slow kidney disease progression.

The biggest limitation is the small number of studies (only five) and the small total number of people studied (339). The studies also measured outcomes differently, making comparisons difficult. Some studies had design issues that could have affected results. The researchers couldn’t determine if certain groups of patients (like those with very advanced kidney disease) benefit more than others. Finally, most studies were relatively short-term, so we don’t know if benefits last over many years.

The Bottom Line

If you have chronic kidney disease, talk to your doctor about combining regular exercise with nutritional counseling. The evidence suggests this may improve your heart fitness and overall health, though it may not directly slow kidney disease. Start slowly with exercise and work with a kidney specialist and dietitian to make sure any changes are safe for your specific stage of kidney disease. (Confidence level: Moderate for heart fitness benefits; Low for kidney function benefits)

This research is most relevant for people with stages 3-5 chronic kidney disease who aren’t yet on dialysis. It’s especially important for those wanting to improve their overall fitness and health. People already on dialysis or who’ve had kidney transplants should follow different guidelines. Anyone with kidney disease should consult their nephrologist (kidney doctor) before starting new exercise programs.

Heart fitness improvements may appear within weeks to a few months of consistent exercise and dietary changes. However, effects on kidney function (if any) would take longer to measure and may take months to years to become apparent. Don’t expect kidney disease to reverse, but rather to slow its progression.

Want to Apply This Research?

  • Track weekly exercise minutes (target: 150 minutes of moderate activity) and daily servings of fruits, vegetables, and protein sources. Log any changes in energy levels and exercise tolerance every two weeks
  • Set a specific weekly exercise goal (like three 30-minute walks) and plan one nutritional change (like adding a vegetable to dinner). Use the app to schedule exercise sessions and meal prep reminders, and track completion rates
  • Monthly check-ins to review exercise consistency and dietary adherence. Quarterly reviews with your doctor to monitor kidney function tests (creatinine and GFR levels). Track subjective measures like energy, mood, and physical capability alongside objective exercise data

This research summary is for educational purposes only and should not replace professional medical advice. Chronic kidney disease is a serious condition requiring ongoing medical supervision. Before starting any new exercise program or making significant dietary changes, consult with your nephrologist (kidney specialist) and registered dietitian, especially if you have advanced kidney disease. The findings in this review are based on limited studies and should be considered preliminary. Individual results may vary, and what works for one person may not work for another. Always follow your doctor’s specific recommendations for your kidney disease stage and overall health status.