The experimental diet was inspired by the religious festival of Ramadan, whereby Muslims fast during the day and consume a carbohydrate-rich meal after sundown. Published in the Nutrition in the Prevention and Treatment of Abdominal Obesity journal, the researchers said findings revealed a link between evening carbohydrate consumption and the diurnal pattern of leptin the 'satiety hormone', ghrelin the 'hunger hormone', and adiponectin—the link between abdominal obesity, insulin resistance and metabolic syndrome.
"Lower hunger scores and greater improvements in anthropometric, biochemical, and inflammatory parameters were observed compared to controls," they wrote.
"We propose that a simple dietary manipulation that can modify hormonal profiles, induce weight loss, and break the vicious metabolic cycle of abdominal obesity has numerous advantages over pharmaceutical and surgical interventions and should be used as a first line of treatment," they added.
The Israeli research involved 78 Tel Aviv police officers aged 25-55 with an average BMI of 30, screened to exclude those with cardiovascular diseases, hypertension, diabetes mellitus, or individuals that had followed any type of diet regime within the previous year or were pregnant. A total of 63 participants completed the study.
After height, weight, abdominal circumference and body fat percentage was recorded, the participants were assigned randomly to either the control or experiment group. The experimental group received a standard low-calorie diet (20% protein, 30–35% fat, 45–50% carbohydrates, 1300–1500 kcal) with carbohydrates at dinner time only, while the control group was given a standard low-calorie diet (20% protein, 30–35% fat, 45–50% carbohydrates, 1300–1500 kcal) with carbohydrates throughout the day.
Fasting blood samples were taken at eight in the morning, and then at four-hour intervals, with participants also filling out hunger/satiety questionnaires every four hours on the first day of the study. This was repeated after one week, three months and six months.
Significant weight loss and reductions in abdominal circumference, BMI, and percentage body fat were found in both experimental and control groups, with this being much greater on average in the experimental group by the end of the study.
Hunger-satiety scores were 13.7% higher after 180 days on the experimental diet compared to the first week of the diet. In contrast, the control group reported a 5.9% lower score compared to this starting point.
The researchers said they had expected to see an overall increase in feelings of hunger in the experimental group, rising with the hunger hormone ghrelin. However the hunger-satiety scores showed this was not the case.
"We propose that the change in ghrelin’s curve to lower relative concentrations in the afternoon may contribute to the enhanced daytime satiety experienced by the experimental diet group. We believe that the alteration in the timing of ghrelin’s peak from daylight hours to the evening just before dinner was another cause for the elevated daylight hour satiety, improved persistence in the weight loss process, and better anthropometric outcomes that were measured," they said.
Source: Nutrition in the Prevention and Treatment of Abdominal Obesity
Published online ahead of print, doi:10.1016/B978-0-12-407869-7.00035-0
"Chapter 35. A Diet with Carbohydrates Eaten Primarily at Dinner: an Innovative, Nutritional Approach to End the Vicious Cycle of Abdominal Obesity”
Authors: S. Sofer, A. Stark, G. Fink and Z. Madar