Hebrew U research: Swing with your hormones

Eating complex carbs in the evening helps to lose weight, feeling full and lowers risk for heart disease and diabetes.

November 9, 2012 04:09
3 minute read.

Pasta 370. (photo credit: Marc Israel Sellem)


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If you want to feel more satiated, lose weight and reduce your risk for heart disease and diabetes, the solution is a meal of mostly complex carbohydrates, but only in the evening, new Hebrew University research says.

Doctoral student Sigal Sofer randomly assigned 78 police officers to either the experimental diet of carbohydrates at dinner and other foods during the day – or a control weightloss diet of carbohydrates and other foods throughout the day.

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Sixty-three participants finished the six-month program. Those who saved their carbohydrates for a meal three hours before bedtime did significantly better than those who ate them throughout the day.

The experimental diet influenced the secretion patterns – in the evening – of hormones responsible for hunger and satiety, as well as those associated with pre-diabetes metabolic syndrome.

The researchers examined the experimental diet’s effect on the secretion of leptin, ghrelin and adiponectin. Leptin is considered the satiety hormone – whose level in the blood is usually low during the day and high at night; ghrelin is considered the hunger hormone – whose level in the blood is usually high in the day and low during the night; and adiponectin is considered the link between obesity, insulin resistance and the metabolic syndrome – whose curve is low and flat in people who suffer from obesity.

Sofer carried out the study under the auspices of Prof. Zecharia Madar, chief Education Ministry scientist, at the Institute of Biochemistry, Food Science and Nutrition at HU’s Robert H. Smith Faculty of Agriculture, Food and Environment.

The study has just been published in the Obesity Journal of the Nature Publishing Group. A connected paper was published in Nutrition, Metabolism & Cardiovascular Diseases.

Sofer told The Jerusalem Post that she got the idea from Ramadan, during which nothing is eaten during the day, but meals made up largely of carbohydrates are eaten after sundown for 30 days.

Madar said that when Muslims fast during the day and eat high-carbohydrate meals in the evening, their blood shows that the secretion curve of leptin changes.

The policemen in the experiment, most of them Jewish, were put into two groups – who did not fast – those who consumed their carbohydrates in the evening, and those who did so at any time they chose.

Sofer said that both groups received a balanced diet, including complex carbohydrates – whole-wheat bread, rice and pasta – with the study group concentrating their carbs in the evening.

The policemen observed their evening regimen at home, but spent one day at a police facility where blood samples were taken from them.

The researchers found that the innovative dietary manipulation led to changes in daylight hormonal profiles in favor of the dieters: The leptin curve became convex during daylight hours, with a nadir in the late day; the ghrelin curve became concave, peaking only in the evening hours; and the adiponectin curve, considered the link among obesity, insulin resistance and the metabolic syndrome, was elevated.

At the same time this dietary pattern led to lower hunger scores and better anthropometric (weight, abdominal circumference and body fat), biochemical (blood sugar, blood lipids) and inflammatory outcomes, compared to the control group.

The findings suggest there is an advantage in concentrating carbohydrate intake in the evening, especially for people at risk of developing diabetes or cardiovascular disease due to obesity. “The findings lay the basis for a more appropriate dietary alternative for those people who have difficulty persisting in diets over time,” said Madar. “The next step is to understand the mechanisms that led to the results obtained.”

“It’s an evolutionary mechanism. People in ancient times had to search for food, which wasn’t possible at night, but today, they just go to the refrigerator,” Sofer explained.

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