This study used data from the French NutriNet-Santé cohort study to analyze the impact of meal timing and frequency and duration of nighttime fasting on cardiovascular disease (CVD) risk. A long-term follow-up study of more than 100,000 participants found that eating late breakfast and late dinner increased overall CVD risk, with this association being particularly strong in women. Additionally, a protective effect was confirmed in that the longer the nightly fasting period, the lower the risk of cerebrovascular disease. These results suggest that not only diet quality but also when you eat are very important for cardiovascular health, emphasizing that encouraging early eating patterns may help prevent cardiovascular disease.

1. Introduction: Meal times and the importance of cardiovascular health ⏰🥗

Cardiovascular disease (CVD) is a leading cause of death and disease burden worldwide, and diet is one of the risk factors that significantly contributes to the development of this disease. The busy lifestyle of modern society often leads to irregular meal times, leading to bad eating habits such as skipping breakfast or eating a late dinner. 😥

The organs of our body move according to a certain circadian rhythm, and the eating-fasting cycle plays an important role in regulating the rhythm of major organs, such as the liver, heart, kidneys, and pancreas. It also affects cardiometabolic functions, including blood pressure regulation. Recently, a new field of research called chrononutrition has emerged, focusing on uncovering the relationship between meal times, circadian rhythms, and health.

Several observational and interventional studies have shown that eating breakfast regularly is important for cardiometabolic health. Conversely, it is known that skipping breakfast can increase the risk of overweight, obesity, CVD, and diabetes. Studies have shown that late dinners are also associated with cardiovascular risk factors such as arteriosclerosis, obesity, and dyslipidemia. However, these studies had limitations in that there was a lack of consensus on meal definitions and that there were many arbitrary interpretations, which could lead to classification errors. 🧐

Meanwhile, there is a growing body of research showing that Time-Restricted Eating (TRE), i.e. extending the nightly fasting period to 12 hours or more, can improve cardiovascular health indicators. In animal experiments, it was reported that restricting meals only during activity periods improved metabolic health, including preventing obesity, and positive effects such as weight loss, lower blood pressure, and reduced inflammation were also found in humans. However, there is still a lack of research examining the direct association between nighttime fasting duration and CVD risk.

The main objective of this study is to explore the impact of time of first meal of the day, time of last meal of the day, number of meals, and duration of nighttime fasting on CVD risk using data from the French NutriNet-Santé cohort. These findings suggest that adopting an earlier eating pattern may help prevent cardiovascular disease. 💡

2. Study results: Association between meal timing and CVD risk 📊

A total of 103,389 participants (79% female) participated in the study, with an average age of 42.6 years. They submitted an average of 5.7 dietary records. The results of the study were really interesting!

2.1. How meal timing and frequency of meals affect CVD risk 🕰️🍽️

• Delayed time of first meal: For each hour delayed the first meal of the day, overall CVD risk increased by 6%. (HR = 1.06, 95% CI 1.01–1.12, P = 0.02)
• Last meal delay: Delaying the last meal was not significantly associated with overall CVD risk, but eating dinner after 9 PM was associated with a 28% increased risk of cerebrovascular disease compared to eating before 8 PM. (HR = 1.28, 95% CI 1.05–1.55, P-trend < 0.01)
• Number of meals: No association was found between the number of meals per day and CVD risk.** 🤷‍♀️
• Coronary artery disease: Neither meal timing nor number of meals was associated with coronary artery disease risk.

2.2. Association between night fasting duration and CVD risk 🌙➡️☀️

• An inverse correlation** was observed, with each hour of overnight fasting leading to a 7% lower risk of cerebrovascular disease. (HR = 0.93, 95% CI, 0.87–0.99, P = 0.02) This suggests that overnight fasting may have a positive effect on cerebrovascular health.
• However, nocturnal fasting duration was not significantly associated with overall CVD or coronary artery disease risk.

2.3. Differences by gender ♀️♂️

One of the most striking findings from this study was gender differences.

• Late first meal times and late last meal times were associated with increased overall CVD and cerebrovascular disease risk, with these associations stronger in women than men.
• Additionally, a significant gender interaction was observed in the association between nighttime fasting duration and coronary artery disease risk. This means that for women, a late eating pattern may make them more vulnerable to cardiovascular health.

2.4. Sensitivity analysis and additional findings 🧪

The main results remained relatively stable through various sensitivity analyses. Some notable points are:

• An inverse correlation was found with longer intervals between last meal and bedtime lower overall CVD risk. This supports the idea that eating too late before going to bed is not a good habit. 🛌
• Key associations remained unchanged after adjusting for factors such as 'eating jet lag'.

3. In-depth discussion: Why are meal times important? 🤔

This large-scale cohort study is significant in that it revealed a direct link between meal times, fasting, and the occurrence of cardiovascular disease, which previous studies had not addressed.

3.1. The importance of meal times 🕒

"It is noteworthy that late first meal and late last meal were independently associated with increased overall CVD risk."

Our body has a specific time frame that is ideal for metabolizing food. Sensitivity to insulin and glucose levels is highest early in the morning and decreases as the day progresses, showing that our bodies are primed to consume and digest energy at specific times. ☀️

• Animal studies showed that delaying the first meal led to metabolic abnormalities, including weight gain, liver lipid accumulation, and increased adipose tissue, while eating late at night caused circadian rhythm disruption, weight gain, and inflammation.
• There is also evidence from human studies that late dinners are associated with glucose intolerance, insulin resistance, increased cholesterol and triglyceride levels, and higher BMI. 😱 It is said that eating food during the resting period when melatonin levels are high can cause glucose intolerance and high blood sugar.

3.2. Differences based on gender Gender differences 👩‍⚕️👨‍⚕️

"The association between late first and last meals and higher overall CVD risk was stronger in women than in men."

This may be related to anatomical and physiological sexual dimorphisms of the circadian system. In fact, the association between circadian disruption due to shift work and cardiovascular disease also tends to be stronger in women.

3.3. The potential of time-restricted eating 🚀

"An inverse correlation was observed in which the longer the duration of night fasting, the lower the risk of cerebrovascular disease."

These results support the positive impact of time-restricted eating (TRE), especially early-TRE, eTRE. This means that increasing the nighttime fasting time by not skipping breakfast and eating your first and last meals early in the day may be more beneficial to your cardiovascular health. For example, this is consistent with previous research showing that eating breakfast before 8 a.m. and fasting at night for more than 13 hours lowers the incidence of type 2 diabetes. 👍

3.4. Strengths and limitations of the study 🔬

This study has the strong strengths of large sample size, prospective design, and detailed assessment of eating behavior through dietary records. It is also important to note that a long-term follow-up study revealed a long-term association between meal timing and CVD.

But there are also some limitations.

• Data on sleep time, sleep quality, chronotype (an individual's biological rhythm type), etc. were obtained only from some, not all, participants, which may have resulted in insufficient statistical power. 😴
• Due to the nature of observational studies, there is a limitation that remaining confounding variables cannot be completely excluded. For example, it would have been difficult to control for all other factors that affect circadian rhythms, such as exposure to night light, time taken medications, and time spent doing physical activity.
• "Reverse causation due to behavioral changes in participants with health problems that make it difficult for them to get out of bed in the morning cannot be completely ruled out."

Participants in the NutriNet-Santé cohort were voluntary participants and tended to have a higher proportion of women, higher socioeconomic status, and healthier lifestyles than the general population, so caution is needed when generalizing the findings. However, we tried to adjust for these factors as much as possible through sensitivity analysis.

"In conclusion, in this large prospective study, late first and last meal times were associated with increased overall CVD risk."

This study highlights the importance of meal timing as well as the nutritional quality of the diet, and suggests that recommending an early mealtime pattern to patients and the general public may help promote cardiovascular health. In the future, efforts will be needed to reconfirm these results through large-scale cohort studies in more diverse environments and minimize potential confounding variables. 🧑‍🔬

Conclusion: Smart meal times for a healthy life 🕰️💖

This NutriNet-Santé cohort study reminds us once again of the importance of meal timing for cardiovascular health. In particular, it is a very important message that late breakfast and late dinner can increase the risk of cardiovascular disease, and that securing sufficient time for nighttime fasting can be positive for cerebrovascular health. 🌟

In particular, the stronger association between meal timing and CVD risk appears in women, demonstrating the need for gender-specific health guidelines. Remembering that not only what we eat but also when we eat have a great impact on our health, wouldn't it be good to make it a habit to finish meals as early as possible and have sufficient nighttime fasting time? 🍎⏰

Of course, CVD is a multi-factorial disease, so meal timing alone cannot explain everything, but this study suggests that smart meal timing selection, along with a healthy diet** may be an important key to protecting our cardiovascular health. Starting today, have a hearty breakfast and an early dinner! How about practicing healthy eating habits? 😊