Your body has an internal clock that helps control how you use energy and stay healthy. Scientists wanted to see if the foods you eat—especially proteins, fats, and carbs—could affect how this clock works. They studied 19 adults and found that what you eat might influence your body’s clock genes differently depending on whether you’re at a healthy weight or overweight. The connections between food and your body’s clock seem to change throughout the day. While these results are interesting, scientists need to study more people to be sure these patterns are real and helpful.

The Quick Take

  • What they studied: Whether the types of food you eat (proteins, fats, and carbohydrates) affect the genes that control your body’s internal clock and daily rhythms
  • Who participated: 19 adults, mostly women, with an average age of 43 years. Some had a healthy weight while others were overweight or had obesity
  • Key finding: The study found that eating different amounts of protein, fat, and carbs appeared to connect with how active certain clock genes were, but these connections were different for people at healthy weights versus those who were overweight. The timing of when blood was tested also mattered
  • What it means for you: This suggests that when and what you eat might help your body’s internal clock work better, but much more research is needed before doctors can give specific eating advice based on this idea. Don’t change your diet based on this small study alone

The Research Details

This was a small exploratory study that looked at 19 adults divided into two groups: those with a healthy weight and those who were overweight or had obesity. Each person kept a detailed food diary for three days, writing down everything they ate and drank. Scientists then took blood samples from each person between 8 a.m. and 4 p.m. and tested how active four specific clock genes were in their blood cells. They looked for patterns between what people ate and how their clock genes behaved.

The researchers compared the two weight groups to see if they had different patterns. They also looked for connections between how much protein, fat, and carbs each person ate and how active their clock genes were. Because blood was collected at different times of day, they could also see if the time of day mattered for these connections.

Understanding how food affects your body’s internal clock is important because this clock controls many things—like when you feel hungry, how you burn calories, and how your body handles sugar. If we can learn how to eat in ways that support a healthy clock, it might help people maintain a healthy weight and prevent diseases. However, most research on this topic has only been done in animals, so studying real people is a necessary step

This study is very small (only 19 people), which means the results might not apply to everyone. Most participants were women, so we don’t know if the same patterns would show up in men. The study only looked at three days of eating, which might not represent someone’s normal diet. The researchers found some interesting patterns, but they weren’t strong enough to be completely certain they’re real. This is why scientists call it a ‘brief report’—it’s meant to share early findings that need more testing, not to give final answers

What the Results Show

When comparing the two weight groups, the researchers didn’t find major differences in how active the clock genes were overall. However, they did notice some trends, especially with two genes called PER2 and CRY that seemed to behave slightly differently between groups.

The most interesting finding was about protein. People in the overweight and obesity group ate a noticeably higher percentage of their daily calories from protein compared to the healthy-weight group.

When looking at connections between specific foods and genes, the patterns were different depending on weight and time of day. In people with healthy weights, eating more fat and protein seemed connected to higher activity of two genes (BMAL1 and CRY). In people who were overweight or had obesity, eating more fat and carbs seemed connected to higher activity of a gene called CLOCK.

The timing of when blood was collected appeared to matter for these connections. This makes sense because your body’s clock changes throughout the day, so the same food might affect your genes differently depending on when you eat it. The study suggests that the relationship between food and your body’s clock is complex and depends on multiple factors working together—your weight, what you eat, and when you eat it

Animal studies have shown for years that diet can affect clock genes, but very few human studies have looked at this. This research adds to the small amount of human evidence we have. It confirms that diet might matter for clock genes in people, but the patterns are more complicated than what we see in animals. The findings suggest we need more research to understand how these connections work in real life

The biggest limitation is the very small number of people studied—19 is too small to be confident the results apply to everyone. The study only included three days of food tracking, which might not show someone’s typical eating habits. Most participants were women, so we don’t know if men would show the same patterns. The researchers only measured genes in blood cells, not in other parts of the body where clock genes might behave differently. Finally, the study was designed to explore patterns, not to prove cause-and-effect, so we can’t say that changing your diet will definitely change your clock genes

The Bottom Line

Based on this early-stage research, there are no specific dietary recommendations to make yet. The findings are interesting but too preliminary to guide eating choices. If you’re interested in supporting your body’s internal clock, stick with general healthy eating advice: eat balanced meals with protein, healthy fats, and whole grains, and try to eat at consistent times each day. Talk to a doctor or dietitian before making major diet changes

This research is most relevant to scientists studying how diet affects metabolism and body rhythms. People interested in nutrition science and how their bodies work might find it interesting. However, people looking for specific dietary advice to lose weight or improve health should wait for larger, more definitive studies. This is not yet ready to guide personal health decisions

Because this is very early research, there’s no realistic timeline for practical benefits. Scientists will need to conduct much larger studies in diverse groups of people before we know if changing your diet based on these findings would actually help. This process typically takes several years of additional research

Want to Apply This Research?

  • Track your meal timing and macronutrient breakdown (protein, fat, carbs percentage) for one week, noting the time of day for each meal. Also track your energy levels and sleep quality at the same times to look for personal patterns
  • Try eating meals at consistent times each day for two weeks and note any changes in hunger, energy, or sleep. This supports your body’s natural clock rhythm while you wait for more research on specific macronutrient timing
  • Create a simple log of meal times, general food types, and how you feel (energy level, hunger, sleep quality) at the same times each day. Look for your own personal patterns rather than trying to match the research findings. Share patterns with a healthcare provider if you notice significant changes

This research is preliminary and based on a very small study of only 19 people. The findings should not be used to make changes to your diet or health routine. Always consult with a doctor, registered dietitian, or qualified healthcare provider before making significant dietary changes, especially if you have any medical conditions, take medications, or have concerns about your weight or metabolism. This article is for educational purposes only and does not constitute medical advice.