There's even more evidence a 'high-fat Mediterranean diet' can boost your heart health, new research suggests

• Low-carb, high-fat diets may be less risky for heart health than previously thought.
• A new study found people who ate low carbs with plenty of unsaturated fat had improved insulin resistance as well as cholesterol levels.
• It's not clear whether more restrictive low-carb diets may have health risks.

Some low-carb diets may actually be heart-healthy, new research suggests, contrary to old fears about the health risks of eating too much fat.

According to a study published September 28 in The American Journal of Clinical Nutrition, diets rich in unsaturated fats like fatty fish, olive oil and nuts may help lower cholesterol and stabilize blood sugar.

Researchers from the Boston Children's Hospital, Framingham State University, and Harvard Medical school conducted a randomized controlled feeding trial to see how low-carb diets might affect markers of insulin resistance and heart health.

The researchers looked at 164 overweight and obese participants, without diabetes or heart disease, who had completed a calorie-restricted weight loss diet. Following the weight loss, they were assigned one of three different weight maintenance diets for five months: a low-carb diet (no more than 20% of daily calories from carbs), moderate carb (40%), or high carb (60%).

The researchers found that lowering carbs was linked to significant improvements to measures of insulin resistance, the body's ability to respond to the hormone insulin to manage blood sugar levels, a key factor in type 2 diabetes risk.

The low-carb dieters also didn't show any signs of side effects from the high-fat diet. In fact, measures of heart health such as their cholesterol levels, blood pressure, and triglycerides remained stable or improved.

These results suggest that a low-carb, high-fat diet may have promising benefits for overall health, and less risky than previously believed.

Previously, experts have warned that low carb and keto diets high in saturated fat may be risky for health

Low carb and keto diets have been controversial as they've grown in popularity in recent years, as dietitians and doctors have voiced concerns about the health risks of eating too much fat. Saturated fat, in foods like butter, bacon, eggs, full-fat dairy, and red meat has been linked to higher levels of LDL or "bad" cholesterol and a higher risk of heart disease.

Still, growing evidence has found low-carb diets can be effective for weight loss and diabetes control.

The researchers wanted to test whether the benefits of low-carb came at the cost of higher risk of heart problems, potentially because of the high fat content of the diet.

Participants on the low-carb diet consumed 21% of their daily calories from saturated fat, and still saw improvements in heart health, suggesting that the benefits of low-carb may outweigh the proposed risks, at least in some cases.

However, researchers noted that it's not clear from the study whether more restrictive low-carb diets, such as those with 10% or less of daily calories from carbs, may be risky for heart health. The study also didn't examine how a low-carb diet may affect some high-risk populations, since participants were relatively healthy and had low cholesterol from the start.

Unsaturated fat sources like fish and olive oil are linked to health benefits in eating styles like the Mediterranean diet

Part of the benefits of low-carb, in this and other studies, may be due to unsaturated fat found in foods like nuts, seeds, avocado, olive oil, and fatty fish like salmon.

Participants in this study ate about two-thirds of their dietary fat in the form of unsaturated fat sources.

Other research has found diets high unsaturated fats, like the Mediterranean diet, are linked to health benefits including lower risk of chronic diseases like diabetes.