Low carb or low fat, which one is the winner?

If weight loss were a sprint, low-carb dieting would win hands down. It is not completely certain why people lose weight faster on low-carb diets, although one of the most likely explanations is that they are better at suppressing appetite for a time, making it easier to achieve the ultimate goal of all diets, cutting calories. However, results from two studies summarized in the August issue of the Harvard Health Letter show that with regards to weight loss, low carb and low fat diets end up in a statistical tie after a year.


In the first study, published last year, low-carb dieters spurted ahead of their low-fat counterparts during the first six months, only to regain pounds in the next six. In the second study, published earlier this year, the low-carb group kept off the pounds, but the low-fat group caught up with them by continuing to lose weight.


However, because obesity can be a lifelong issue for many people, the August issue advises that longer studies are needed to examine long-term weight loss progress of both diets, not just results for a year.


As for the health effects, chief objections to low-carb dieting have been that they can increase levels of "bad" LDL cholesterol. But both year-long studies found that low-carb and low-fat diets had the same effect on LDL levels. And low-carb diets outdid low-fat diets with respect to other blood fats related to heart disease.


The August issue of the Harvard Health Letter imparts three other important messages:


-- Low-carb dieting can be improved by sticking with polyunsaturated and monounsaturated fats and choosing whole grains as your carbs.


-- Diets have differing effects on cholesterol levels and metabolic factors. If you're considering losing weight, talk to your doctor about getting a cholesterol test. The results can help you choose the best diet.


-- Because of taste, upbringing, genetics, and other factors, the individual response to diets varies tremendously. Experiment to see what works for you.


The Harvard Health Letter is available from Harvard Health Publications, the publishing division of Harvard Medical School for $28 per year. Subscribe at health.harvard/health or by calling 1-877-649-9457.