A one-year study of obese children examined the impact of a low-fat, high-carbohydrate diet fed ad libitum on body weight; insulin sensitivity and hormones involved in hunger, metabolism, and insulin resistance (such as ghrelin, adiponectin, and leptin levels). Ghrelin is known as the “hunger hormone,” and short-term studies on calorie-restricted diets have shown it increases with weight loss, which predictably would be associated with increased hunger, making calorie restriction more difficult to sustain over time. However, the results of this study showed that in the 16 kids who lost a significant amount of weight over a year that their ghrelin levels did not increase. The authors “…speculate that the missing compensatory increase in ghrelin levels in reduction of overweight allows the weight loss to be sustained.”1
Higher ghrelin is usually associated with greater hunger, so the fact that ghrelin did not increase despite significant loss of body weight suggests this may be one reason a lower-fat, higher-carbohydrate diet often produces substantial weight loss even when calorie intake is not consciously restricted. It would appear the kids in this study, like adults in other studies, did not get hungrier and eat more as they lost body fat. This study also showed increased insulin sensitivity, increased adiponectin (associated with reduced insulin resistance) and lower leptin levels (seen with loss of body fat).Bottom Line: There are many possible reasons reducing the percent of fat while increasing the percent of carbohydrate in the diet may be beneficial for long-term sustained weight loss. Data from the National Weight Control Registry suggests that the vast majority of Americans who are successful at losing a lot of weight and keeping it off eat a diet substantially lower in fat and higher in carbohydrate than most other Americans. This study suggests weight loss on such a diet can be achieved without a substantial increase in hunger that undermines efforts to keep weight off with a higher-fat diet.By James Kenney, PhD, RD, LD, FACN.1. Internat’l J. of Obesity. 2005;29:362-8.