Low Carb Diet

Can a Low-Carb Diet Be Heart Healthy?

Low-carb diets have been a popular weight-loss tool for years. They’ve also been shown to help with diabetes management. But are these high-fat, low-carb meal plans safe for your heart?

Recent research on low-carb diets and heart health

A recently published, well-designed study in The American Journal of Clinical Nutrition found that a high-fat, low-carb diet may improve heart health in people who are overweight or obese, at least in the short term.

Study participants were divided into three groups:

  • 20% carbohydrate intake
  • 40% carbohydrate intake
  • 60% carbohydrate intake

All three groups consumed 20% of their daily calories from protein. The remaining percentage of their diets were comprised of fat. (For reference, most Americans eat about 50% carbohydrates on a daily basis, mostly the highly processed variety.)

Study participants decreased refined, processed or sugary carbs such as:

  • Baked goods
  • Candy
  • Cake
  • White bread
  • White rice
  • White pasta
  • Sugary beverages

All participants increased their intake of fiber-rich foods like:

  • Vegetables
  • Fruits
  • Nuts
  • Seeds
  • Lentils
  • Beans

No one was placed on a ketogenic (“keto”) diet. The keto diet restricts carbohydrate intake to 10% or less each day.

After five months, participants on the low-carb, high-fat plan didn’t have any negative changes in their cholesterol levels, which might normally be expected. Their LDL (“bad”) cholesterol levels stayed the same as those in the high-carb group. However, those on the low-carb, high-fat plan:

  • Had an average 15% decrease in lipoprotein(a) levels. High levels of lipoprotein(a) are strongly linked to heart disease and stroke.
  • Had an average 15% decrease in lipoprotein insulin resistance (LPIR) scores. Lower scores are associated with lower diabetes risk. Participants in the high-carb group experienced a 10% increase in their LPIR scores.

We might have expected that people eating the high-fat, low-carb plans would have higher unhealthy cholesterol levels, but that wasn’t the case with these participants—at least in the short term. The participants were only required to follow these plans for five months. We need more research to understand the long-term effects of low-carb, high-fat diets.  

Are carbs unhealthy?

Carbohydrates are an essential macronutrient and part of a healthy diet. Carbs are found in many non-starchy, unprocessed, fiber-rich foods like:

  • Vegetables
  • Fruit
  • Nuts
  • Seeds
  • Beans
  • Lentils

And for most people, it’s safe to eat a moderate amount of starchy carbs that are minimally processed or unprocessed, like:

  • Sweet potatoes
  • Oatmeal
  • Brown rice
  • Quinoa

The biggest takeaway I want you to remember is that it’s always a good idea to cut back on highly processed, refined starchy carbs like:

  • Baked goods
  • Juice
  • Soda
  • White bread, pasta and rice
  • Chips
  • Candy
  • Pizza
  • Crackers

When you limit or avoid processed, refined carbs and fill your plate with vegetables, healthy fats, lean protein and fiber, you’ll avoid blood sugar spikes and crashes. This will help you:

The healthiest sources of fat

If you choose to replace some carbohydrates with fat, choosing healthy fat sources is essential. While study participants consumed some saturated fat (like red meat, butter and cheese), they mostly ate unsaturated fat. Unsaturated fat has well-documented heart health benefits. It’s found in foods like:

  • Fish
  • Olive oil
  • Avocados
  • Eggs
  • Nuts
  • Seeds

If eating healthy fat, moderate carbohydrates, lean protein, plenty of fiber and lots of plant-based foods sounds familiar, it should: The Mediterranean diet has a vast body of evidence showing its heart health benefits.

So, while it’s OK for most people to eat saturated fat in moderation, a substantial body of research shows it’s best to avoid high amounts of it.   

Talk to your health care provider about your diet

Nutrition research is ever-evolving. And it’s important that we look at the long-term effects of certain meal plans.

I encourage you to talk to your primary care provider or dietitian about what meal plan is best for you. We’re all different and have varying nutritional needs. Consulting with your health care provider is especially important if you have a chronic condition like:

Listen to your body and choose foods that help you feel your best mentally and physically. And if you have questions, talk to your medical provider. Find a provider near you

Ryane Greene

Ryane Greene, MHS, RD, LDN

Licensed and Registered Dietitian
Pardee UNC Health Care
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