Both Skipping Meals and Eating Frequently Linked to a Higher Risk of Death

According to a large new prospective study examining both meal frequency and the intervals between meals in adults aged 40 and older, intervals of 4.5 hours or less between meals were associated with a higher risk of death from all causes than longer intervals.

The study also showed that eating one meal a day was associated with higher mortality rates from both cardiovascular disease (CVD) and all causes compared with eating three meals. However, statistical significance disappeared when participants diagnosed with CVD or cancer at baseline were excluded from the analysis.

In brief, the study emphasizes that eating without being hungry is unhealthy and suggests that the recently popular practice of eating 1 meal a day may not be as healthy as people think.

“Eat Small, Frequent Meals” and “One Meal Is Enough for Me”: Sayings Worth Rethinking

Dr. Yangbo Sun of the University of Tennessee Health Science Center, the study's lead author, said these findings would raise new questions about the health benefits of restricting the number of daily meals and the intervals between them.

“intermittent fasting is widely promoted as a solution for weight loss, metabolic health and disease prevention. This study is important for adults, a large proportion of whom eat fewer than three meals each day,” Dr. Sun said at a press conference. “Our research showed that individuals who eat only one meal a day have a higher risk of death than those who eat more meals a day.”

Dr. Sun said, “Compared with those who eat 3 meals a day, participants who skip breakfast are more likely to develop cardiovascular disease, while those who skip lunch or dinner have a higher risk of death from all causes.”

“Based on these findings, we recommend eating at least two to three meals spread throughout the day,” Dr. Sun said.

The findings of this study of adults in the United States were published in Journal of the Academy of Nutrition and Dietetics. Among people who eat three meals a day, an average interval of 4.5 hours or less between two meals is associated with the risk of death from all causes. The authors believe this is the first study to demonstrate this association.

Is It When We Eat or What We Eat?

However, Dr. Courtney Peterson of the Department of Nutrition Sciences at the University of Alabama has reservations about the study.

Dr. Peterson pointed out that “the devil is in the details” and that the researchers needed to properly account for and discuss calorie intake and, most importantly, medical conditions and diseases diagnosed at the start of the study.

“However you analyze it, they got great results basically showing that skipping a meal is bad for you, right? Unfortunately, when they removed everyone who had cancer or heart disease at baseline, almost nothing was statistically significant anymore.”

Dr. David Unwin, who studies diabetes control using low-carbohydrate diets, noted that as an epidemiological study (based on population observation), this study suggests association rather than causation.

“A much better study seems to contradict this,” Dr. Unwin noted. A meta-analysis of randomized controlled trials published in the BMJ in 2019 found that participants who skipped breakfast lost more weight in trials relating breakfast consumption to weight change and energy intake.

Dr. Unwin added, “For me, the quality of what we eat is much more important than when we eat, especially avoiding ultra-processed junk food,” citing studies showing that consuming ultra-processed foods increases the risk of death from all causes.

He specifically noted that “sugar content accounts for the largest part of the association between junk food and death. My motto is to eat only real food, such as plenty of green vegetables, meat, nuts, eggs, milk and dairy products, and fruit.”

How Do Eating Frequency and Meal Intervals Affect Health?

According to the 2009-2010 United States National Health and Nutrition Examination Survey (NHANES), 40% of Americans skip meals, and at least one in five people skip breakfast or lunch.

Dr. Sun also said, “We already know that skipping breakfast is not a good idea for cardiovascular health, but we were curious about other meals during the day, such as lunch and dinner. We also wanted to learn whether the intervals between meals were associated with mortality.”

The researchers also felt a need to address the health outcomes associated with meal frequency, skipping meals and meal intervals because recommendations on these issues were not included in the 2020-2025 Dietary Guidelines for Americans owing to a lack of evidence.

A total of 24011 adults aged 40 and older from NHANES (between 1999-2014) participated. Dr. Sun said, “We based our study on a nationally representative sample of adults in the United States whose findings can be translated directly to the general population.”

Eating behaviors, including 24-hour food and beverage recall surveys and eating times, were collected between 1999-2014. Using mortality data through December 31, 2015, potential associations between eating behaviors and mortality were calculated, including deaths specifically due to CVD and deaths from all causes.

Shorter Intervals Between Meals—Frequent Eating—Show Worse Outcomes

The results show an association between mortality and eating frequency, the time between two meals and skipping meals.

When meal frequency throughout the day (1 to 4 meals) was related to cardiovascular and all-cause mortality, the results showed that fewer meals were associated with higher mortality.

Sun and colleagues point to several possible reasons why skipping meals could be a risk factor for disease and death. First, they highlight food insecurity, which has been shown to be associated with a higher risk of cardiovascular disease, and add that skipping breakfast in particular may be a behavioral marker of an unhealthy diet and adverse lifestyle habits. However, when participants diagnosed with cardiovascular disease or cancer at baseline were excluded from the analysis, the results for meal frequency were no longer significant.

Regarding the relative effect of skipping any meal compared with skipping none, the researchers found, after adjusting for the factors listed earlier, that missing breakfast had a nonsignificant hazard ratio of 1.1 for all-cause mortality, but a ratio of 1.4 for cardiovascular disease (CVD) mortality.

Skipping lunch was associated with a significant hazard ratio of 1.12 for all-cause mortality and a nonsignificant hazard ratio of 1.15 for CVD mortality. Similarly, skipping dinner was associated with a significant hazard ratio of 1.16 for all-cause mortality and a nonsignificant hazard ratio of 1.19 for CVD mortality.

When the researchers examined meal intervals, they found results that may seem a little confusing but make sense on reflection. Compared with the group whose meal intervals were 4.6-5.5 hours, the groups with intervals of 4.5 hours or less and more than 5.5 hours showed a significant association with all-cause mortality, but a nonsignificant association with CVD mortality. In other words, both frequent eating and skipping a main meal appeared unfavorable.

Frequent Eating or Skipping Meals Overloads Metabolism

Dr. Sun and the other study authors point to several possible reasons why skipping meals could be a risk factor for disease and death. First, they highlight food insecurity, which has been shown to be associated with a higher CVD risk, and add that skipping breakfast in particular may be a behavioral marker of unhealthy dietary and lifestyle habits.

“However, the results remained significant after adjustment for food insecurity or lack of access to quality food and various dietary and lifestyle factors, including smoking, alcohol use, physical activity levels, total energy intake and overall diet quality. This makes them less likely explanations for the observed association between skipping meals and death.” they write.

They also emphasize that skipping meals generally means eating meals with a larger energy load, which may increase the burden of regulating glucose metabolism and lead to metabolic dysfunction.

“This may also explain the association between a shorter meal interval and death, because a shorter wait between meals also means a larger energy load within a given period.”

The senior investigator, Dr. Wei Bao, an epidemiologist at the University of Iowa, said, “Our findings are based on observations from publicly available data and do not imply causation. Nevertheless, what we observed makes sense from a metabolic perspective.”