How Much Fat Is Safe for the Heart?

City of Hope
Friday, 5 March 2004

Study Shows a Moderate-Fat Almond Diet Results in Greater Weight Loss and Blood Pressure Reduction than a Low-Fat Diet

A study presented today at the American Heart Association's Annual Conference on Cardiovascular Disease Epidemiology and Prevention showed that in two groups eating two different diets containing the same number of daily calories over six months, one group of patients lost more weight and further reduced their blood pressure than the other group.

Timely News

The study comes at a time when the nutrition community is debating the heart-health effects and long-term effectiveness of high- or moderate-fat, low-carbohydrate diets. While popular low-carbohydrate diet plans are sweeping the nation, research is not yet definitive on these factors.

Also timely, the almond study shows that all calories may not be 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. In this study, even though the daily caloric intake of the two groups was equal, the almond group lost more weight than the other.

Heart-Health Implications

"This research suggests that a moderate-fat, lower-carb diet indeed can have a beneficial effect on the heart – at least when the fat is the heart-healthy monounsaturated type," said Michelle Wien, Dr.P.H., R.D., C.D.E., the study's lead researcher at City of Hope National Medical Center in Duarte, Calif.

Weight Loss Implications

"For years, people have associated almonds with gaining weight, but this study demonstrates that almonds can be an effective part of a weight-loss diet," Wien said. "There may be qualities in almonds that helped the first group lose more weight."

One possible explanation for the effects observed in the 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 not contributing calories (Ren et al., 2001). This has led some to question whether all of the calories in almonds as determined by the bomb calorimeter, which measures calories, are actually absorbed by the human body.

And, almonds are convenient and satiating. "After hearing the results of this study, one of my patients has begun carrying a one-ounce handful of almonds in a little tin that previously contained mints," she said. "This is a satisfying on-the-go snack – she eats it, she feels full, and the tin helps her control the portion size."

Diabetes Implications The study's findings regarding diabetes were consistent with previous research on almonds' role in controlling glucose levels in people with type 2 diabetes (Lovejoy et al., 2002).

Study Format 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.

The study was originally published in the November issue of the International Journal of Obesity.

REFERENCES:

Ren Y., Waldron K.W., Pacy J.F., Ellis P.R. Chemical and histochemical characterization of cell wall polysaccharides in almond seeds in relation to lipid bioavailability. Biologically active phytochemicals in food. (ed) W. Pfannhauser, G.R. Fenwick & S. Khokhar, Royal Soc. of Chemc., Cambridge, UK, 2001: 448-52.

Lovejoy J.C., Most M.M., Lefevre M., Greenway F.L., Rood J.C. Effects of diets enriched in almonds on insulin action and serum lipids in adults with normal glucose tolerance in type 2 diabetes. Am J Clin Nutr 2002; 76:1000-6.

City of Hope is one of the world's leading research and treatment centers for cancer, diabetes, HIV/AIDS and other life-threatening diseases. Named by U.S. News and World Report as one of America's best medical centers for cancer treatment, City of Hope is a pioneer in the fields of bone marrow transplantation and genetics. Founded in 1913, City of Hope is a Comprehensive Cancer Center, the highest designation of the National Cancer Institute, and is a founding member of the National Comprehensive Cancer Network. For more information, visit www.cityofhope.org.

The Almond Board of California administers a grower-enacted Federal Marketing Order under the supervision of the United States Department of Agriculture. Established in 1950, the Board's charge is to promote the best quality almonds, California's largest tree nut crop. For more information on the Almond Board of California or almonds, visit www.AlmondBoard.com.

For more information, or to contact City of Hope, see their website at: www.cityofhope.org