Low-Fat Diets Don’t Deliver on Heart Health

Unless you're living on another planet, you've heard this message: reduce your intake of fat and cholesterol to achieve a healthy weight and decrease the likelihood of developing heart disease. In fact, the terms “healthy" and “low fat" seem inextricably linked. But now we know that the rationale for a low-fat diet is based on two overly simplistic ideas that turn out to be wrong.

Wrong Idea #1
Fat contains 9 calories per gram; both protein and carbohydrate contain 4 calories per gram. Presumably then, reducing fat intake should allow you to eat a larger total volume of food, feel satisfied, and promote weight loss. Only one problem; it doesn't work. Just ask all the people who've cut their fat intake, but haven't lost body fat or have actually gained weight.

Why doesn't it work? The simple reason is that the amount of calories increases when carbs replace fat because fat is inherently more satisfying than carbs and you wind up eating more carbs as you seek satisfaction and a sense of fullness. Where's the proof that the low-fat approach has backfired? Just look at the skyrocketing rates of obesity (and diabetes) over the past 40 years. That's the same period in which we've been told to cut down on fat—and, as a nation, we have.

Wrong Idea #2
The major emphasis on reducing dietary fat (including saturated fat) was based on the assumption that consuming fatty foods increases blood cholesterol levels, which, in turn, which in turn, increases the incidence of heart disease. This assumption is called the “diet-heart hypothesis." However, despite decades of research funded by the government at a cost of billions of dollars, there's little evidence to support the premise.

A Look at the Research
The largest and most expensive study on the role of fat in the diet was called the Women's Health Initiative, which tracked almost 50,000 postmenopausal women for an average of eight years. The women were randomly assigned to one of two diets: one that reduced total fat intake and increased the intake of vegetables, fruits and grains and a control group that was allowed to eat whatever they wanted. Many different researchers published many scientific papers on this study. All came to the same conclusion: there was no significant benefit in terms of weight loss as a result of following a low-fat diet. Nor was there any impact on the incidence of heart disease (or diabetes or cancer).

It turns out that you are not what you eat, so much as what your body does with what you eat. That's where following the Atkins low-carb approach comes in. Once you eliminate added sugar, white flour and other “junk" carbs and reduce your total intake of carbs, you convert your body to a primarily fat-burning metabolism. The result is that your excess fat stores become a source of energy and your indicators for heart disease improve, as supported in a number of recent studies.

A Sweet Reversal
We're encouraged to see that based upon a recent study published in Circulation: the Journal of the American Heart Association, the association now takes the position that consuming added sugars may cause weight gain and raise triglycerides, both of which contribute to the risk of developing heart disease. It also offers specific guidelines for the upper limits of added sugar intake. In 2006, the American Heart Association (AHA) recommended reducing intake of added sugars, but set no limits. (The study classifies added sugars as any sugar or syrup added at the table or in the processing and preparation of a food, in contrast to naturally occurring sugars in fruit, for example.) The AHA now says that “a prudent upper limit of intake is half of the discretionary calorie allowance, which for most American women is no more than 100 calories per day and for most American men is no more than 150 calories per day from added sugars." Six teaspoons of sugar pack about 100 calories and a 12-ounce cola contains about 130 calories.

Most Americans eat far in excess of these amounts. A report from the 2001-04 National Health and Nutrition Examination Survey (NHANES) showed the average intake of added sugars by Americans was about 22 teaspoons a day. Lead author of the Circulation study Rachel K. Johnson says that sugar has no nutritional value other than to provide calories. We at Atkins couldn't agree more, which is why our posture is that one should strive to control carbohydrate intake and avoid all added sugars. We hope that in its next position statement, the AHA tackles the larger issue of overall carbohydrate intake and its association with heart health.

Selected references:
1. B. V. Howard, J. E. Manson, M. L. Stefanick, S. A. Beresford, G. Frank, B. Jones, et al., “Low-Fat Dietary Pattern and Weight Change over 7 Years: The Women's Health Initiative Dietary Modification Trial," The Journal of the American Medical Association 295 (2006), 39–49.
2. L. F. Tinker, D. E. Bonds, K. L. Margolis, J. E. Manson, B. V. Howard, J. Larson, et al., “Low-Fat Dietary Pattern and Risk of Treated Diabetes Mellitus in Postmenopausal Women: The Women's Health Initiative Randomized Controlled Dietary Modification Trial," Archives of Internal Medicine 168 (2008), 1500–1511.
3. S. A. Beresford, K. C. Johnson, C. Ritenbaugh, N. L. Lasser, L. G. Snetselaar, H. R. Black, et al., “Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial," The Journal of the American Medical Association 295 (2006), 643–654.
4. R. L. Prentice, C. A. Thomson, B. Caan, F. A. Hubbell, G. L. Anderson, S. A. Beresford, et al., “Low-Fat Dietary Pattern and Cancer Incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial," Journal of the National Cancer Institute 99 (2007), 1534–1543.
5. C. D. Gardner, A. Kiazand, S. Alhassan, S. Kim, R. S. Stafford, R. R. Balise, et al., “Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors among Overweight Premenopausal Women: The A TO Z Weight Loss Study: A Randomized Trial," The Journal of the American Medical Association 297 (2007), 969–977.
6. I. Shai, D. Schwarzfuchs, Y. Henkin, D. R. Shahar, S. Witkow, I. Greenberg, et al., “Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet," The New England Journal of Medicine 359 (2008), 229–241.
7. J. S. Volek, M. L. Fernandez, R. D. Feinman, and S. D. Phinney, “Dietary Carbohydrate Restriction Induces a Unique Metabolic State Positively Affecting Atherogenic Dyslipidemia, Fatty Acid Partitioning, and Metabolic Syndrome," Progress in Lipid Research 47 (2008), 307–318.
8. J. Nordmann, A. Nordmann, M. Briel, U. Keller, W. S. Yancy, Jr., B. J. Brehm, et al., “Effects of Low-Carbohydrate vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors: A Meta-analysis of Randomized Controlled Trials," Archives of Internal Medicine 166 (2006), 285–293.
9. M. Dashti, N. S. Al‑Zaid, T. C. Mathew, M. Al‑Mousawi, H. Talib, S. K. Asfar, et al., “Long Term Effects of Ketogenic Diet in Obese Subjects with High Cholesterol Level," Molecular and Cellular Biochemistry 286 (2006), 1–9.
10. G. Boden, K. Sargrad, C. Homko, M. Mozzoli, and T. P. Stein, “Effect of a Low-Carbohydrate Diet on Appetite, Blood Glucose Levels, and Insulin Resistance in Obese Patients with type 2 Diabetes," Annals of Internal Medicine 142 (2005), 403–411.
11. E. C. Westman, W. S. Yancy, Jr., J. C. Mavropoulos, M. Marquart, and J. R. McDuffie, “The Effect of a Low-Carbohydrate, Ketogenic Diet Versus a Low-Glycemic Index Diet on Glycemic Control in type 2 Diabetes Mellitus," Nutrition & Metabolism (London) 5 (2008), 36.
12. E. H. Kossoff, and J. M. Rho, “Ketogenic Diets: Evidence for Short- and Long-Term Efficacy," Neurotherapeutics 6 (2009), 406–414.
13. R. K. Johnson, L. J. Appel, M. Brands, et al., “Dietary Sugars Intake and Cardiovascular Health," Circulation 2009;120;1011-1020.