Changes in LDL ('bad') cholesterol levels were not significant. In both studies, at six months, the low-carb group had lost more weight than the low-fat group, but at the end of the 12-month study, both the low-carb and low-fat groups had lost about the same amount of weight.
For one year, researchers at the Veterans Affairs Medical Center in Philadelphia followed 132 obese adults randomized into two groups. One restricted carbohydrate intake to less than 30 grams per day (low-carbohydrate diet); the other restricted caloric intake by 500 calories, with 30 percent of calories from fat (conventional diet). Eighty-three percent of the study group had diabetes or other risk factors for heart disease.
In the low-carb group, triglyceride levels decreased more and HDL ('good') cholesterol levels decreased less than in the low-fat group. (High levels of trigylcerides, a fat in the blood, are associated with heart disease.) People with diabetes on the low-carb diet had better control of blood sugar.
At the six-month mark, the low-carb group had lost more weight than the low-fat group, as reported in a previously published article. However, by the 12-month point, both groups had lost about the same amount of weight (11 to 19 pounds for the low-carb group and 7 to 19 pounds for the low-fat group). The low fat group continued to lose weight from 6 to 12 months, whereas the average weight in the low-carb group remained steady after 6 months.
This twelve-month study is the longest study comparing low-carb vs. low-fat diets using subjects who have a high prevalence of diabetes.