Researchers studied 10 young adults with high blood pressure to see if eating unhealthy food at different times of day affected their health. They found that eating a Western-style meal (high in salt, sugar, and fat) in the evening caused the body to hold onto salt overnight and kept blood pressure elevated at night. In contrast, eating the same meal in the morning allowed the body to get rid of extra salt during the day and had less impact on nighttime blood pressure. This small study suggests that when young people with high blood pressure eat unhealthy foods might be just as important as what they eat.

The Quick Take

  • What they studied: Does eating an unhealthy Western-style meal (salty, sugary, fatty foods) at different times of day affect blood pressure and kidney function in young adults with high blood pressure?
  • Who participated: 10 young adults (average age 26 years, half male and half female) who had elevated blood pressure or early-stage high blood pressure
  • Key finding: Eating an unhealthy meal in the evening caused the body to hold onto salt overnight and kept blood pressure higher at night, while eating the same meal in the morning allowed the body to eliminate salt during the day and had less impact on nighttime blood pressure
  • What it means for you: If you have high blood pressure, eating unhealthy foods earlier in the day may be better for your blood pressure control than eating them at night. However, this is a very small study, so more research is needed before making major changes to when you eat

The Research Details

This was a small controlled feeding study where 10 young adults with high blood pressure participated in two different meal scenarios. In one scenario, they ate a Western-style meal (high in salt, sugar, and unhealthy fats) in the morning, and in the other scenario, they ate the exact same meal in the evening. The meals had the same number of calories so researchers could fairly compare the effects of timing. The researchers measured how much salt the participants’ bodies got rid of through urine over 24 hours and monitored their blood pressure continuously throughout the day and night using portable monitors. Each participant did both scenarios so researchers could compare how their bodies responded to the same meal eaten at different times.

Our bodies have internal clocks that control many functions, including how we handle salt and regulate blood pressure. This study is important because it looks at whether eating unhealthy foods at the wrong time of day might be especially harmful for people with high blood pressure. Most previous research focused on what people eat, not when they eat it. Understanding the timing of meals could help doctors give better advice to young adults trying to control their blood pressure.

This study is small (only 10 people), which means the results might not apply to everyone. However, it was carefully controlled—all participants ate the exact same meals with the same calories, just at different times. The researchers used objective measurements like 24-hour urine collection and continuous blood pressure monitoring, which are reliable ways to measure these health markers. The study design (crossover) where each person did both scenarios is strong because it reduces differences between people. The main limitation is the very small sample size, so these findings need to be confirmed in larger studies before making major health recommendations.

What the Results Show

When participants ate the unhealthy meal in the morning, their bodies got rid of more salt through urine during the day (0.84% compared to 0.35%). This is actually a good thing because it means their kidneys were working to eliminate the excess salt. However, when they ate the same meal in the evening, their bodies held onto salt overnight instead of getting rid of it (0.48% at night compared to 0.39%), which is concerning. Blood pressure during waking hours was higher after the morning meal (126/80 mmHg compared to 121/77 mmHg), but the evening meal caused a different problem: blood pressure stayed elevated at night instead of dropping as it normally does. The morning meal caused higher daytime blood pressure, while the evening meal disrupted the normal nighttime drop in blood pressure that usually helps protect heart health.

The next morning after eating the evening meal, resting blood pressure was slightly higher (121.8 mmHg compared to 119 mmHg). The researchers noticed that after the evening meal, the body appeared to be protecting itself by storing salt, which may have prevented even higher nighttime blood pressure spikes. This suggests the body has protective mechanisms, but these mechanisms may not be enough to fully prevent the harmful effects of eating unhealthy foods late at night.

Previous research has shown that eating unhealthy Western-style foods is bad for blood pressure and kidney function, but most studies didn’t look at whether the time of day matters. This study adds to growing evidence that our body’s internal clock (circadian rhythm) affects how we process food and regulate blood pressure. Other research has shown that eating late at night is associated with weight gain and metabolic problems, and this study suggests it may also affect blood pressure control differently than eating the same foods earlier in the day.

The biggest limitation is that only 10 people participated, which is a very small group. Results from such a small study may not apply to everyone, especially people of different ages, races, or with different types of high blood pressure. The study only lasted a short time, so we don’t know if these effects continue over weeks or months. All participants were young adults (average age 26), so results may not apply to older people. The study only tested one type of unhealthy meal, so we don’t know if the timing matters for other foods. Finally, the study was done in a controlled setting where people ate exactly what researchers gave them, which is different from real life where people make their own food choices.

The Bottom Line

If you have high blood pressure, try to eat unhealthy foods (high in salt, sugar, and saturated fat) earlier in the day rather than in the evening. However, the best recommendation is to eat fewer of these unhealthy foods overall, regardless of timing. This evidence is moderate strength because it comes from a small study, so talk to your doctor before making major changes to when you eat. For now, focus on eating more healthy foods like fruits, vegetables, and whole grains, and reducing salt intake throughout the day.

This research is most relevant to young adults (ages 18-40) who have been told they have elevated blood pressure or early-stage high blood pressure. If you have normal blood pressure, this study suggests it’s still good to avoid eating unhealthy foods late at night, but the timing may be less critical. People with more severe high blood pressure or other heart conditions should definitely talk to their doctor about meal timing. This research is less relevant to older adults, as the study only included young people.

You might notice changes in blood pressure within days to weeks if you shift when you eat unhealthy foods, but the most important changes happen over months and years. The best approach is to gradually reduce unhealthy foods overall while also paying attention to when you eat them. Don’t expect dramatic improvements from timing alone—the biggest benefits come from eating healthier foods in general.

Want to Apply This Research?

  • Track the time you eat meals high in salt, sugar, or saturated fat, and note your blood pressure readings at different times of day (morning, afternoon, evening, and night if possible). Look for patterns between when you eat unhealthy foods and when your blood pressure is highest.
  • Set a goal to eat any high-salt, high-sugar, or high-fat foods before 6 PM instead of after dinner. Use the app to log these meals and set reminders to eat dinner earlier. Gradually replace evening snacks with healthier options like fruit, vegetables, or nuts.
  • If you have a home blood pressure monitor, check your blood pressure at the same times each day (morning, afternoon, evening) for 2-4 weeks while tracking meal times. Compare your blood pressure patterns before and after shifting when you eat unhealthy foods. Share these patterns with your doctor to see if timing changes help your specific situation.

This research is from a small pilot study with only 10 participants and has not yet been confirmed in larger populations. The findings are preliminary and should not replace medical advice from your doctor. If you have high blood pressure or are taking blood pressure medication, talk to your healthcare provider before making significant changes to when you eat, especially if you’re considering changing meal times as part of your treatment plan. This study does not provide medical advice, diagnosis, or treatment recommendations. Always consult with a qualified healthcare professional about your individual health situation.