Adding fuel to the latest debate in the nutrition community, a study published November 1, 2003 in the International Journal of Obesity shows that in two groups eating two different diets containing the same number of daily calories over six months, one group lost more weight than the other.
In the study, 65 overweight and obese adults -- 70 percent of whom had type 2 diabetes -- were put on one of two diets designed for weight loss. The first group ate a liquid formula-based, low-calorie diet containing moderate fat from almonds (39 percent total fat, 25 percent monounsaturated fat, 35 percent carbohydrate as percent of energy). The second group ate a liquid formula-based, low-fat, low-calorie diet including self-selected complex carbohydrates (18 percent total fat, 5 percent monounsaturated fat, 53 percent carbohydrates as percent of energy). The two diets' calorie count and protein levels were equivalent.
After 24 weeks, patients on the moderate-fat diet containing almonds had achieved a greater reduction in weight/BMI (-18 percent vs. -11 percent), waist circumference (-14 percent vs. -9 percent), fat mass (-30 percent vs. - 20 percent) and systolic blood pressure (-11 percent vs. 0 percent).
Both groups experienced lower glucose and insulin levels. But medication requirements for individuals with type 2 diabetes decreased more steadily in the low-calorie almond diet than the low-calorie complex carbohydrate diet.
The study comes at a time when the nutrition community is beginning to wonder, based on other recent studies, whether all calories are really created equal. One of the most hallowed nutrition beliefs has always been that losing weight hinges solely on the number of calories consumed versus the calories burned through resting energy expenditure and physical activity.
One possible explanation for the effects observed in Dr. Wien's study is that the fat in almonds may not have been completely absorbed. This is consistent with a study published in 2001 that concluded that the cell walls of almonds act as a physical barrier to the absorption of fat. The fat is then excreted from the body, thereby failing to contribute calories (Ren et al., 2001). This has led some to question whether all of the calories in almonds as determined by the bomb calorimeter are actually absorbed by the human body.
This study's findings regarding diabetes were consistent with previous research on almonds' role in controlling glucose levels in people with type 2 diabetes. For example, in a previous a two-phase study involving 20 healthy, free-living individuals, researchers first examined the effect of 100 grams of almonds a day on insulin levels and fasting glucose levels. Almonds did not cause an increase or decrease in insulin levels or glucose. In phase two, participants with type 2 diabetes enrolled in one of 4 diets, and after a two- week break, they switched to another diet. The four diets were high-fat with almonds, low-fat with almonds, high-fat control and low-fat control.