Health gurus give out many diet plans based on the proportion of carbohydrates, proteins, and fats one ingests as a method to promote weight loss, but the effectiveness of these diet charts have never been brought into light.
Now, a study, led by Dr. Karen Foster-Schubert of the University of Washington School of Medicine in Seattle, Washington, has shed light on potential mechanisms by which various diets promote weight loss.
The study examined the relative ability of different nutrient types to suppress ghrelin, which is secreted by the stomach and is the only known appetite-stimulating hormone.
Circulating ghrelin levels increase shortly before meals and then decrease promptly after ingestion of food.
"We found that when fat is consumed, levels of ghrelin remain relatively high, which could in turn stimulate hunger. Protein consumption resulted in the greatest suppression of ghrelin over a long period and, interestingly, consumption of carbohydrates resulted in a strong ghrelin suppression initially, although subsequent ghrelin levels rebounded well above baseline," Foster-Schubert said.
In the study, subjects were given three beverages with widely varying compositions of macronutrients (carbohydrates, fats, and proteins). Blood samples were taken before the first beverage was ingested and every 20 minutes for six hours thereafter.
Researchers then measured the ghrelin levels in each sample.
"These findings open the door to future research on the effectiveness of varying methods of dieting. Improving our understanding of the regulation of ghrelin by ingested macronutrients could facilitate rational design of weight-reducing diets," Foster-Schubert said.
The study is published in the Journal of Clinical Endocrinology & Metabolism (JCEM).