Researchers looked at data from over 31,000 Americans to understand if eating a high-fat diet increases the chances of developing kidney stones. They found that people who ate more fat had about a 23% higher risk of getting kidney stones compared to those who ate less fat. This connection stayed true even after accounting for other health factors. While this is interesting news, scientists say we need more long-term studies to fully understand how diet affects kidney stone formation and what changes people should make to their eating habits.

The Quick Take

  • What they studied: Whether eating a diet high in fat makes it more likely for someone to develop kidney stones
  • Who participated: Over 31,000 Americans of various ages and backgrounds who participated in a national health survey between 2007 and 2020
  • Key finding: People who ate high-fat diets had a 23% higher risk of kidney stones compared to those eating lower-fat diets. This finding was statistically significant, meaning it’s unlikely to be due to chance alone
  • What it means for you: If you’re concerned about kidney stones, reducing fat intake might be worth discussing with your doctor. However, this is one study showing a connection, not proof that fat causes stones. Talk to a healthcare provider before making major diet changes

The Research Details

This was a cross-sectional study, which is like taking a snapshot in time. Researchers looked at information collected from thousands of Americans through national health surveys conducted between 2007 and 2020. They used questionnaires and interviews to ask people about their eating habits (specifically how much fat they consumed) and whether they had ever been diagnosed with kidney stones.

The researchers then used statistical tools to look for patterns—specifically, whether people who ate more fat were more likely to have kidney stones. They adjusted their analysis to account for other factors that might affect kidney stone risk, like age, weight, and other health conditions, to make sure the fat connection wasn’t just due to these other factors.

This type of study is useful for finding associations between diet and health conditions, but it can’t prove that one thing directly causes another.

Understanding dietary risk factors for kidney stones is important because kidney stones affect about 1 in 11 people worldwide and can cause serious pain and health problems. If we can identify foods that increase risk, people might be able to prevent stones by changing what they eat. This study looked at a very large group of people over many years, which makes the findings more reliable than smaller studies.

This study used real-world data from a well-respected national health survey, which is a strength. The large sample size (over 31,000 people) also makes the results more trustworthy. However, because it’s a cross-sectional study, it only shows that high-fat eating and kidney stones are connected—it doesn’t prove that eating fat causes stones. People who eat high-fat diets might differ in other ways that also affect kidney stone risk. The study also relied on people remembering and reporting their diet, which can be inaccurate.

What the Results Show

Out of the 31,059 people studied, about 9.7% (roughly 3,000 people) had a history of kidney stones. When researchers compared people with high-fat diets to those with lower-fat diets, they found that high-fat eaters had a 23% increased risk of kidney stones. In statistical terms, this means the odds ratio was 1.23, with a confidence interval of 1.06-1.42, and the p-value was 0.008—all of which indicate this finding is unlikely to be due to random chance.

The connection between high-fat diet and kidney stones remained even after the researchers adjusted for many other factors that could influence kidney stone formation, such as age, sex, body weight, physical activity, and other dietary factors. This suggests the fat connection is independent of these other variables.

When researchers looked at specific subgroups (like different age groups or genders), the relationship between high-fat diet and kidney stones was consistent across all groups, meaning the effect wasn’t stronger in some populations than others.

The study didn’t report major secondary findings, but the consistency of results across different subgroups suggests the high-fat diet effect is fairly universal across different types of people. The researchers noted that high-fat diets are known to cause chronic inflammation and changes in gut bacteria, which could be the biological mechanisms explaining why fat intake might increase kidney stone risk.

This study builds on previous research showing that certain dietary patterns—particularly the ketogenic diet, which is very high in fat—are associated with kidney stone formation. The findings align with what scientists know about how high-fat diets affect metabolism and inflammation in the body. However, most previous research focused on specific diets rather than overall fat intake in the general population, so this study provides new information about the broader relationship between dietary fat and kidney stones.

This study has several important limitations. First, it’s cross-sectional, meaning it’s like a photograph rather than a movie—we can see associations but not prove cause and effect. Someone with kidney stones might have changed their diet after diagnosis, so we can’t be sure if high-fat eating caused the stones or if the stones caused people to change their diet. Second, the study relied on people’s memories of what they ate, which can be inaccurate. Third, the researchers couldn’t account for all possible factors that might influence kidney stone formation, such as hydration levels or family history. Finally, the study was observational, so there could be unmeasured differences between high-fat and low-fat eaters that explain the results.

The Bottom Line

Based on this research, people concerned about kidney stone prevention might consider moderating their fat intake, especially if they have other risk factors for kidney stones. However, this is a moderate-confidence recommendation because the study shows association, not causation. Anyone with a personal or family history of kidney stones should discuss dietary changes with their doctor or a registered dietitian. General healthy eating guidelines already recommend limiting saturated fat, so this finding aligns with existing nutrition advice.

This research is most relevant for people who have had kidney stones before, those with a family history of kidney stones, or people with other risk factors like obesity or certain metabolic conditions. Men are more likely to develop kidney stones than women, so this may be particularly relevant for men. People following very high-fat diets (like ketogenic diets) should be especially aware of this potential risk. However, the findings don’t mean everyone needs to drastically change their diet—they suggest that moderation in fat intake may be one factor in kidney stone prevention.

If someone reduces their fat intake, they wouldn’t expect to see immediate changes. Kidney stone formation is a gradual process that develops over months or years. If dietary changes do reduce kidney stone risk, it would likely take several months to years to see a measurable difference in stone formation rates. This is why long-term dietary consistency matters more than short-term changes.

Want to Apply This Research?

  • Track daily fat intake in grams and monitor any symptoms related to kidney health (such as back pain, painful urination, or blood in urine). Set a target based on dietary guidelines (typically 25-35% of daily calories from fat) and log meals to see patterns in fat consumption.
  • Users could set a goal to identify and reduce high-fat foods in their diet, such as fried foods, fatty meats, and full-fat dairy products. The app could suggest lower-fat alternatives and track progress toward a more balanced fat intake while also monitoring hydration (important for kidney stone prevention).
  • Establish a baseline of current fat intake, then gradually reduce it over 4-8 weeks while tracking any changes in symptoms or health markers. Monitor trends monthly and adjust goals based on progress. For those with kidney stone history, correlate dietary changes with any medical follow-ups or imaging results over time.

This research shows an association between high-fat diets and kidney stones but does not prove that fat causes kidney stones. This information is for educational purposes and should not replace professional medical advice. If you have a history of kidney stones, are experiencing symptoms like severe back pain or painful urination, or are considering significant dietary changes, please consult with your healthcare provider or a registered dietitian. Individual risk factors vary greatly, and what applies to the general population may not apply to your specific situation. Always discuss dietary modifications with your doctor, especially if you have existing health conditions or take medications.