Capsule SummaryFour groups of men eating different carbohydrate levels and different levels of saturated fat were followed for changes in blood lipids (cholesterol and triglycerides). First, they all ate the same diet, then they were divided into the different diet groups -- first without weight loss, then with reduced calories.
- The low-carb groups improved on most of the parameters of cholesterol and triglycerides, even without weight loss.
- With weight loss, there was further (but smaller) improvement in the low-carb groups, and the high carb group partially caught up, but not all the way.
- These trends included LDL particle size, with the low-carb groups going in the “good” direction. Additionally, the group that was higher in saturated fat had the greatest increase in particle size. More Information about Cholesterol and Low-Carb Diets, including particle size
- Most of the changes with the “medium carb” diet were intermediate between the higher and lower carb diets.
- On a calorie intake designed to keep weight stable, the low-carb groups still lost weight.
More Details About the Study178 men participated in this 13-week study.
Phase 1 (Baseline): During Week 1, everyone ate the same diet. which was 54% carbohydrate, 16% protein, and 30% fat, similar to standard recommendations such as the Food Pyramid.
Phase 2 (Diet Changed, Weight Same): During the next 3 weeks, the participants were each assigned to one of four diet groups:
- same diet as first week
- 39% carbohydrate with low (7% to 9%) saturated fat (essentially the Zone Diet)
- 26% carbohydrate with low saturated fat (perhaps similar to Phase Two of the South Beach Diet, depending on the individual)
- 26% carbohydrate with 15% saturated fat (perhaps similar to Atkins Ongoing Weight Loss Phase, again depending on the individual)
- Phase 2 Results: Except, oops, despite the researcher’s best efforts to keep the calories up, the 26% carb groups lost weight anyway –- a little over 2 pounds for the low-saturated fat group and about a pound for the higher sat fat group (and no, it wasn’t all water weight, as the body fat percentages of the people in the low-carb groups also decreased). Even taking weight loss into account, the 26% carb groups had improvements in triglycerides, HDL, total cholesterol, apolipoprotein B, and the ratio of total:HDL cholesterol not accounted for by the weight loss. Also, increases in LDL particle size, particularly in the higher saturated fat group.
- Phase 3 Results: The lower-carb groups made further, but smaller, improvements. The high-carb group also improved, but not as much as the low-carb groups. The 39% carb group was intermediate on most measures.
Interesting Insights From This Study
Krauss, Ronald, et al. “Carbohydrate, Weight Loss, and Atherogenic Dyslipidemia.” American Journal of Clinical Nutrition 2006 May;83(5):1025-31.