A unique head-to-head trial of low-carbohydrate and low-fat diets in people with chronic diseases such as hypertension revealed that while both regimens helped people lose weight, only the people who restricted their daily intake of carbs saw significant reductions in their blood pressure.

The study, reported in the Jan. 25 Archives of Internal Medicine, involved 146 obese, middle-aged patients at the Durham, N.C., Veterans Affairs Medical Center. Half of the patients followed a diet that delivered less than 30 percent of daily calories from fat and also took doses of the prescription fat-blocker Xenical. Alli is the nonprescription-strength version of Xenical; both drugs contain orlistat.

The other half of the patients followed a ketogenic diet. This diet, which is similar to the popular high-protein Atkins Diet, allows patients to consume as much fat as they want but keeps carbohydrate intakes to as low as 15 grams per day-about a single slice of white bread.

Patients in both treatment groups met weekly for education and support, and by the end of the 48-week trial, patients in both groups had lost an average of around 9 percent of their initial body mass. However, patients folowing the low-fat diet had slight increases in blood pressure, on average. Low-carb patients had average reductions in blood pressure of 5.9/4.5 mm Hg.

Study leader William S. Yancy Jr. summed up the findings for Reuters by saying that both “fairly powerful weight loss treatments were equally effective, and one of them was more effective for lowering high blood pressure.”

The study involved too few patients to mandate wholesale changes in the treatment of obesity or weight-related hypertension. Also, as an analysis from the UK National Health Services notes, patients kept on strict high-fat, low-carb diets for long periods can experience nutritional and metabolic problems.

Nonetheless, the evidence that low-carb diets produce greater benefits for patients who need to lose weight and lower their blood pressure suggests that patients and their health care providers should be open to trying a variety of treatments.

Ed Lamb
Norfolk Health Care Examiner