Low-carb or low-fat: which is better for weight loss?

Time to lighten up on the pasta. Oh.

What to cut, what to cut? Well, if you’re trying to lose weight, the answer's carbs.

It turns out that reducing your carb intake is more effective at spurring weight loss than reining in the fat, according to new research published in the Annals of Internal Medicine.

For the study, researchers from Tulane University randomly assigned 148 obese men and women without heart disease or diabetes to follow a low-carbohydrate or low-fat diet. After one year, participants who had been eating low-carb had lost nearly 3.5kg more than those who had been eating less fat. Plus, they had greater decreases in fat mass and other cardiovascular risk factors.

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But before you start raiding your kitchen looking for carbs to trash, it's important to note that, as far as this study is concerned, low-carb really isn't all that low.

In the study, researchers suggested dieters only limit their intake of digestible carbs to 40 grams per day (about as much as in four slices of whole wheat bread) and told them they could eat as many grams of indigestible carbohydrates, or fibre, as they wanted.

And in the end, most of the low-carb-eating participants in the study still ate more: they put away 75 to 85 grams of digestible carbs and about 15 grams of indigestible carbs a day.

Not sure how many grams you're getting of each? Look on the nutrition label. Then just subtract the number of grams of fibre from the total carbohydrate count. That's how many grams of digestible carbs the food packs.

Easier than counting carbs, though, is just paying attention to where your carbs are coming from. "Carefully choosing your carbohydrate sources is key," says lead study author, Lydia A. Bazzano, M.D., Ph.D., a professor and nutrition researcher at Tulane University.

"If most of your carbohydrates are coming from whole vegetables and whole fruits rather than white rice, potatoes, refined grains, and beverages, then improved cardiovascular health and even weight loss is likely to follow."

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And while cutting your numbers of digestible carbs is helpful, this study also shows that fat can actually aid in weight loss, says Bazzano.

Not only did the low-fat dieters lose less weight, but low-carb study participants were actually encouraged to replace digestible carbs with healthy fats - primarily from unsaturated sources - and protein, both of which are known to reduce heart disease risk factors like lipid profile and blood pressure.