Think carbs are the enemy!? Don’t be so sure! An experimental diet with carbohydrates consumed at dinner might actually benefit people suffering from severe and morbid obesity, according to new research at the Hebrew University of Jerusalem.
The carbs-for-dinner diet influences secretion patterns of hormones responsible for hunger and satiety (the desire to limit further food intake, like after a satisfying meal) as well as hormones associated with metabolic syndrome. The research shows that the diet is easier to stick to in the long run and reduces risk factors related to diabetes and cardiovascular disease.
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The research was carried out by research student Sigal Sofer under the guidance of Professor Zecharia Madar. Sofer randomly assigned 78 people to either the experimental diet (carbohydrates at dinner) or a control weight loss diet (carbohydrates throughout the day). Sixty-three subjects finished the six-month program.
The researchers examined the experimental diet’s effect on the secretion of three hormones: leptin, considered to be the satiety hormone, whose level in the blood is usually low during the day and high during the night; ghrelin, considered the hunger hormone, whose level in the blood is usually high during the day and low during the night; and adiponectin, considered the link between obesity, insulin resistance and the metabolic syndrome, whose curve is low and flat in obese people.
The Ramadan connection
“The idea came about from studies on Muslims during Ramadan, when they fast during the day and eat high-carbohydrate meals in the evening, that showed the secretion curve of leptin was changed,” explained Prof. Madar.
The researchers found that the innovative dietary manipulation led to changes in daylight hormonal profiles in favor of the dieters: the satiety hormone leptin’s secretion curve became curved during daylight hours with a low point late in the day; the hunger hormone ghrelin’s secretion curve became concave, peaking only in the evening hours; and the curve of adiponectin, considered the link between 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.
A diet for diet-haters
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 Professor Madar. “The next step is to understand the mechanisms that led to the results obtained.”
The study was published in two continuous papers: “Greater weight loss and hormonal changes after six-month diet with carbohydrates eaten mostly at dinner” (published in Obesity) and “Changes in daily leptin, ghrelin and adiponectin profiles following a diet with carbohydrates eaten at dinner in obese subjects” (published in Nutrition, Metabolism & Cardiovascular Diseases).
The study was conducted at the Institute of Biochemistry, Food Science and Nutrition at the Hebrew University’s Robert H. Smith Faculty of Agriculture, Food and Environment. (Prof. Madar is now Chief Scientist at Israel’s Ministry of Education).