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Higher percentages of saturated fat in low-carb diets may not harm cholesterol levels, new analysis suggests

A secondary analysis of a diet study showed that low-carbohydrate dieters who consumed the most saturated fats had better levels of lipids in their blood.

In the debate of low-fat versus low-carb diets, both can help you shed unwanted weight equally, as long as you’re choosing healthy options. But it turns out a diet composed of fewer carbs and higher percentages of saturated fat might actually have health benefits outside of weight loss — better blood cholesterol levels.

This finding came from a follow up analysis of the DIETFITS study, which set out to contrast the effects of low-carb versus low-fat dieting and determine which was better for losing weight. In a subgroup of 210 low-carb dieters, those who consumed a higher percent of saturated fats as part of their overall diet had better levels of blood lipids, including both higher HDLs (good cholesterol) and lower triglycerides, which are the main type of fat in the blood and in body fat storage.

That's not to say that saturated fats are suddenly exonerated — there's a bit of a catch, said Christopher Gardner, PhD, nutrition expert and senior author of the analysis. Those with the best lipid levels and highest percent of saturated fat intake also ate fewer carbohydrates, particularly added sugars and refined grains.

So the lesson here isn't that saturated fats are good for you, it's that they're not going to topple a good dieting effort that's low in carbs and refined sugars and high in whole foods and vegetables.

A secondary analysis paper detailing the findings appears in The American Journal of Clinical Nutrition. Cindy Shih, former research assistant at Stanford, is the first author.

"The people who were assigned to the low-carb group did a great job at cutting carbs, particularly from added sugars and refined grains. They didn’t get specific guidance about how much fat to eat, and according to their diet records, they didn't eat very differently in terms of the amount of fat intake," said Gardner.

The national guideline for saturated fat consumption is 10 percent of your diet, but since these folks consumed fewer calories from carbohydrates, the percent of fat, including saturated fat, technically increased, since it accounted for a higher proportion of their diet.

"So if one of these people were to go to their doctor the doctor might see an increase in saturated fat percent from 10 to 15 and be concerned. But if you look more closely, you see that the grams of fat they're eating didn't change much, and you see that they have higher HDL levels, stable LDL levels and lower levels of triglycerides."

This, Gardner says, is the punchline: Low-carb dieters with the highest saturated fat percentage had modestly better, not worse, blood lipid levels. But the actual amount of saturated fat they ate wasn’t much different — the high percentage was primarily due to the fact that these folks cut back the most on their carbohydrate intake.

"I want this finding to put people who are on a low-carb diet, and their doctors, more at ease about the percent of saturated fat consumption," said Gardner. "An increase to 15 percent exceeds the guidelines, but what matters most is the grams of fat and carbs, and the weight loss. If you or your patient is more successful at losing weight with a low-carb diet, you might not have to worry so much about the percent of saturated fat."

Photo by sheri silver

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