The low-fat diet for the six-month study consisted of 100-500 calories below the daily requirements with only 30% coming from fat and only a total of 30 mg of cholesterol. The low-fat diet of the twelve-month study was defined as 500 calories below the daily requirements with only 30% coming from fat. The low-carb diets consisted of 20 g of carbohydrates a day and nutritional supplements for the six-month study and 30 g of carbohydrates for the twelve-month study. All participants received nutritional counseling. Results

The Nurses' Health Study showed a positive correlation between diet and relative risk of CVD. However, it did not address what aspect of diet contributed to CVD risk. The next three studies attempted to answer this question by measuring LDL or "bad" cholesterol and HDL or "good" cholesterol levels. The Framingham Study showed that high LDL levels and low HDL levels were positively correlated with an increased risk for CVD. The six-month diet study showed that both a low-fat and a low-carb diet caused weight loss. However, the low-fat diet caused decreases in bad cholesterol with only a small decrease in healthy cholesterol, whereas the low-carb diet caused bad cholesterol to increase...

In the twelve-month study participants lost weight on the low-fat diet, whereas participants in the low-carb diet first lost weight then gained some back. The same LDL and HDL results were seen as in the six-month diet study.
Discussion

The low-fat diet is healthier. Both groups exhibited weight loss. However, in the low-carb diet weight was gained back in the longer term study. In the low-fat diet weight loss was slow but steady, which is healthy.

Also, the low-fat diet caused decreases in bad cholesterol with only a small decrease in healthy cholesterol, whereas the low-carb diet increased bad cholesterol and decreased good cholesterol. Although CVD risk was not lessened with the low-fat diet within one year, it is possible that with slow and steady changes in weight and cholesterol levels that it would over a greater time period. Further studies would be needed to test this hypothesis. The low-carb diet did lower CVD risk in a short-term study, but had no effect on CVD in the one-year study. This potential yo-yo effect in weight loss and CVD risk caused by the low-carb diet is unhealthy.

References

Mayo…