Late-Night eating disadvantages
A study in Nature Communications looked at how changes in eating and fasting affect the number of people getting heart disease.
Introduction
Human bodies have a 24-hour physiological cycle called circadian cycles. These cycles include fasting/eating cycles that set peripheral clocks in different tissues. These clocks help regulate the heart and blood vessels. A new study wants to learn more about how changes in eating and fasting times affect the risk of CVD. CVD is the main cause of disease and death worldwide. What we eat significantly affects our cardiovascular risk. A faulty diet has been linked to almost 8 million CVD-related deaths. In recent years, society has become less focused on traditional meal times. Irregular meal timings have become common. Studying the link between cardiovascular health and the eating/fasting cycle is part of the new field of chrono nutrition. This field aims to understand how meal timings affect our health.
Research shows that eating breakfast is important for normal metabolism and cardiovascular health. But eating late at night can lead to arteriosclerosis, obesity, and abnormal lipid profiles. In women, it can also cause metabolic syndrome. However, there is confusion about when each meal should be eaten and what counts as late-night eating. Time-restricted eating (TRE) may help improve heart and metabolic health. It means fasting for at least 12 hours at night. Studies in humans have shown that this can lead to weight loss, lower blood pressure, and reduced inflammation. This study was done because there isn’t much information on how fasting at night and meal timing affect the risk of cardiovascular disease (CVD). The study, published in Nature Communications, looked at data from the NutriNet-Sante study with over 100,000 adults. The researchers used their food records to make a database on how often they ate and when they ate.
What did the study find?
Younger, single people who smoked regularly, were more active, better educated, had lower incomes, and ate later breakfasts and late-night meals were more likely to have a family history of CVD. Eating later meals increased the risk of variable meal timings, binge drinking, higher alcohol consumption, and later bedtimes. The follow-up period was 7 years, covering almost 700,000 person-years. During this time, there were just over 2,000 new cases of CVD, with an equal distribution between cerebrovascular diseases (including strokes and transient ischemic attacks) and coronary heart diseases (including heart attacks, angioplasty, acute coronary syndrome, and angina). The risk of CVD increased as the first meal was eaten later, but there was no such trend with the timing of the last meal. However, eating after 9 pm increased the risk by 13% compared to before 8 pm. The risk of cerebrovascular disease increased by 8% for each hour of delay in the last meal, with a 28% higher risk after 9 pm compared to before 8 pm.
If you wait longer between your last meal at night and your first meal in the morning, you can reduce your risk of cerebrovascular disease by 7%. However, this decrease in risk does not apply to cardiovascular disease overall or coronary heart disease. Specifically, if you eat your first meal after 9 am instead of before 8 am, and if you have your last meal after 9 pm instead of before 8 pm, your risk of cardiovascular problems increases. This increase is more significant for women than for men. Women also experience more benefits from extending the fasting period at night. Rather than skipping breakfast or delaying your first meal, you can gain the most benefits by increasing the time between meals at night. This is because our bodies are most responsive to insulin and glucose levels in the morning, and this sensitivity decreases throughout the day. Animal studies consistently show that delaying breakfast by four hours leads to weight gain, increased fat, fat accumulation in the liver, and disruption of genes responsible for lipid metabolism.
Research on humans shows that when evening meals are delayed, it can cause problems with glucose regulation, insulin sensitivity, abnormal levels of lipids in the blood, and excessive weight gain. This could be due to eating during the body’s rest period when melatonin levels are highest, which can result in prolonged high levels of glucose in the blood after a meal.
What are the implications?
Cardio metabolic health is best improved by early time-restricted eating (TRE). This is supported by an earlier study from the same group that found people who ate breakfast before 8 am and fasted for more than 13 hours overnight had a lower risk of type 2 diabetes. The findings also show that eating later meals is linked to a higher risk of cardiovascular disease (CVD). Earlier studies have shown that eating breakfast and last meals earlier can improve cardio metabolic risk factors. Timely meals help with food metabolism, which regulates blood pressure by setting peripheral circadian rhythms. Although these findings are suggestive, we need to consider other factors that could affect the results. For example, some people who eat later meals may have night shift work, which is known to be associated with cerebrovascular disease and impaired sleep. However, none of the participants in this study ate meals exceptionally early or late to rule out the effects of night shift work.
This study did not control for factors like exposure to light at night, waking up during the night, timing of exercise or other activities, drinking, and substance abuse. These factors could potentially disrupt our sleep-wake cycle.
