A new study revealed a surprising link between your eating habits and your health and weight: It's not what you eat, but when you eat it, according to research published in the Proceedings of the Nutrition Society.

The study found that people who ate at irregular times weighed more, had larger waistlines, and higher body-mass indices — a measure of obesity — than those who stuck to regular mealtimes.

The study also found that eating irregularly could hurt your overall health and increase your risk of metabolic syndrome, a cluster of bad health conditions that are linked with heart disease and other illnesses.

It's something to think about if you find yourself eating only when you have a moment out of your busy day, stuffing your face with whatever sandwiched item is within reach.

Chronodisruption

You've all heard the advice not to eat after bedtime, though you may not know exactly why. What horror will befall you? Is it like saying "Bloody Mary" into a mirror three times?

It's more like eating irregularly disrupts your internal body clock or circadian rhythm.

"Irregular meal patterns are defined here as food eaten in varying amounts through the day and at different times from one day to the next," the study said. Shift workers suffer the most from irregular eating, especially those working on a night shift, researchers found.

"The evidence for the relationship between shift work and increased disease risk is strongest for cancer," the study reported. Those who work these less-than-ideal hours also have to deal with disrupted sleep patterns. Researchers refer to this as "chronodisruption."

Metabolic syndrome

Researchers grouped men and women from Sweden, around 60 years of age, into two categories based on their answers to surveys about eating habits: "regular eaters" and "irregular eaters."

They then tested the subjects' glucose, insulin, cholesterol, and triacylglycerol levels to see if they were at risk for metabolic syndrome. Metabolic syndrome is what occurs when you've got high blood pressure, high blood sugar, excess body fat around the waist — basically your classic signs of poor health and factors that could lead to diabetes, heart disease, and the like.

Increased risk

The researchers found that irregular eaters had significantly greater weight, waist circumferences, and BMI overall, compared to the regular eaters.

Adults at the ages of 36, 43, and 53 were also asked to keep a five-day food diary, which included pre-defined meal slots for breakfast, lunch, evening meal, and between meal snacks. Researchers then scored the adults on the irregularity of their meal-eating. Their results?

"We found that individuals with a more irregular intake, especially at breakfast, lunch, and between meals, had an increased risk of the metabolic syndrome," the study found.

A surprising suggestion

Buried in the study is the most surprising info of all: Your choice of dining companions may also affect your health.

"An even further step after studying the impact of what and when we eat is to study where we eat and with whom we eat. A recent meta-analysis showed that family meal frequency contributes to more healthy eating among children and adolescents, with positive associations between family meals and adolescent dietary intake including fruit and vegetables consumption, dairy consumption and less consumption of sugar-sweetened beverages."

That makes sense. Perhaps you've noticed that your own eating habits differ depending on whether you're grabbing pizza with your friends or cooking for your own family at home.

So what should you do?

No one is suggesting that you quit your job so that you can eat regularly timed meals (sorry). "Overall, this narrative review showed that it is important to further advance research about not only what people eat but also when they eat," the study said.

If you've been having trouble losing weight, you may want to follow science and start a food diary, noting when you eat along with what you eat, and see if there's a pattern.