For weight loss, popular diets advocate everything from eating according to your blood type to nearly fasting for 2 days a week. Now, one popular instruction - to eat small but frequent meals throughout the day - has been called out by researchers, who say it does not boost metabolism or encourage weight loss.

In fact, the research - presented today at the Society for Endocrinology annual BES conference - suggests counting calories is all that really matters when it comes to losing weight.

Obesity has become a growing public health concern in recent decades. According to the Centers for Disease Control and Prevention (CDC), the percentage of adults over the age of 20 who were overweight or obese in the US as of 2010 was nearly 70%.

The researchers of this latest study, led by Dr. Milan Kumar Piya of the University of Warwick in the UK, note that previous research has suggested eating a single high-fat meal increases low-level inflammation in the body when bits of gut bacteria - known as endotoxins - enter the blood stream.

Since this kind of inflammation has been linked to a future risk of developing cardiovascular disease and type-2 diabetes, the researchers wanted to investigate whether eating often would cause more damage that might increase these risks in obese individuals.

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Eating small, frequent meals does not encourage weight loss or boost metabolism, researchers say.

To conduct their study, the team analyzed 24 lean and obese women who were given two meals or five meals on separate days.

These women consumed the same number of calories on both days, and the researchers meanwhile measured their energy expenditure using whole body monitor calorimeters.

'Counting calories matters most'

Findings from the study revealed that whether the women ate two meals or five meals had no effect on how many calories were burned. Over a 24-hour period, the women burned the same number of calories when they ate both numbers of meals.

Additionally, the investigators observed that obese women who ate five meals had significantly higher endotoxin levels by the end of each day, compared with when they only ate two meals.

Dr. Piya says their research has yielded two main findings:

"Firstly, that the size or frequency of the meal doesn't affect the calories we burn in a day, but what matters most for losing weight is counting calories. Secondly, by carrying more weight, more endotoxin enters the circulation to cause inflammation, and eating more often will exacerbate this risk, which has been linked to metabolic diseases such as type-2 diabetes."

She says their future research will focus on the impact of diet, gut flora and calories burned in different people.

"By understanding how diet affects inflammatory risk and energy expenditure, we will further our understanding of how we can better target diet intervention on an individual basis," she adds.

In other recent nutrition news, Medical News Today reported on a study that questioned the link between saturated fat and heart disease. Researchers who published in the Annals of Internal Medicine said they found no evidence to support guidelines that suggest restricting saturated fat for lowering heart disease risks.