The Effects of a Low-Carb Diet on Cholesterol and Lipids Robert Rynfield Journal of the American Center for Nutrition, vol. 1, no. 1. Published 2022-08-31; Updated: 2023-01-30

Can a Low-Carb Diet Lower Cholesterol?

Consumers consistently search for new ways to reduce body weight, whether for health reasons or to improve self-esteem. Recent diet fads like the keto diet have proven effective for losing weight, but many health professionals have raised concerns regarding the safety of these high-fat, carbohydrate-restricted diets and their impacts on blood lipids and cholesterol.

Although further studies remain necessary, many medical professionals and researchers have investigated the effects of a low-carb diet on lipids. The consensus supports the finding that low-carb diets are effective at improving cardiovascular risk factors. Specifically, cholesterol and lipid levels seem to improve under low-carbohydrate diet conditions.

What Does Science Say About Low Carb and Blood Lipids?

According to several studies and meta-analyses, low-carb diets do not generally lower cholesterol levels. Some studies do report lower levels of low-density lipoprotein (LDL) “bad” cholesterol, but these decreases tend to level out over time or only reduce at nominal rates [1,2]. Although LDL may not decrease, low-carb diets do see a reduction in the size of LDL particles, which may reduce the risk of cardiovascular disease (CVD) [1].

However, studies show that a low-carb diet may successfully lower levels of lipids in the body, most significantly triglycerides. Low-carb diets may also increase high-density lipoprotein (HDL) levels, also known as “good” cholesterol [2].

What Is Considered a Low-Carb Diet?

The definition of a low-carb diet varies depending on the study. One study used a diet consisting of about 60% fat [3]. The keto diet, a trendy low-carb diet, typically recommends the consumption of 70% fat, 20% protein, and 10% carbohydrate. Anything under 50 grams of carbohydrates per day is generally accepted as “low carb”.

is whey or plant protein better

Low-carb diets prioritize fat and protein, so participants often eat a lot of meat and other fatty proteins. Participants in the 60% fat study mainly consumed:

  • Beef
  • Fish
  • Poultry
  • Nuts and peanut butter
  • Seeds

Participants in this study also consumed moderate amounts of eggs, cheese, and protein powder while avoiding high-carb foods, including:

  • Bread
  • Rice
  • Beans
  • Cereal
  • Sweets [3]

In contrast, a low-fat diet may recommend 55% carbohydrate, 30% fat, and 15% protein with a priority of avoiding excessive fat consumption [4]. Researchers have conducted many studies comparing the health effects of low-fat diets to the effects of low-carb diets.

The Difference Between Good and Bad Cholesterol

Most people hear the word “cholesterol” and assume the context must be negative, but the human body needs cholesterol to maintain cell integrity, synthesize hormones, create bile acids, and protect nerve cells. Health issues occur when blood concentrations of cholesterol reach unbalanced levels, increasing the risk of CVDs. 

Not all cholesterol harms the body when levels increase. High levels of HDL have beneficial effects by transporting excess cholesterol to the liver for removal from the body [5].

Low-density Lipoprotein (LDL)

When discussing the effects of a low-carb diet on cholesterol and lipids, many doctors and dieticians focus on LDL or “bad” cholesterol. Low-density lipoprotein particles contain more cholesterol than they do protein, which causes them to stick to arterial walls and create plaque buildup. 

LDL moves throughout the body via the bloodstream. When levels become too high, the person’s risk of cardiovascular disease increases due to the buildup of atherosclerotic plaques. While raising HDL levels may decrease this risk, medical professionals focus on lowering LDL to help prevent heart attacks, strokes, and other cardiovascular outcomes [5].

High-density Lipoprotein (HDL)

While doctors want to see low LDL levels in patients, they want to see high levels of HDL. High-density lipoproteins contain higher amounts of protein than cholesterol, the opposite of LDL. 

Research shows that this “good” cholesterol helps remove bad cholesterol from the body by transporting excess cholesterol to the liver. A higher HDL level seems to support a lower risk of CVDs [5].  

How To Raise HDL (Good) Cholesterol on a Low-Carb Diet

While participants’ LDL levels remained relatively unchanged after six months in one study, HDL levels consistently increased [3]. Many studies illustrate this increased HDL trend when monitoring people on low-carb diets.

Compared to low-fat diets, low-carb eating results in even more significant increases in HDL. However, researchers point out that the HDL to total cholesterol ratio remains relatively similar in low-fat and low-carb diets [2]. 

How To Lower LDL (Bad) Cholesterol on a Low-Carb Diet

While a low-carb diet may not provide the best option for lowering LDL levels, people can take specific steps to reduce CVD risks while limiting carbohydrate intake. These steps include:

  • Decreasing sugar consumption. Studies indicate that a higher intake of sugars results in increased LDL and triglycerides [6]. To lower sugar intake, avoid sweet drinks, bottled sauces, packaged sweets, and other foods with added sugars. 
  • Maintaining oatmeal and barley intake. Although low-carb diets encourage people to avoid grains, barley and oatmeal contain too many benefits to eliminate them from one’s diet completely. Studies show that consuming beta-glucan fiber can help lower lipid and LDL concentrations in the body [7].
  • Exercising. Most people know they should exercise at least five days per week to encourage cardiovascular health, but working out on a regular basis can also reduce LDL and triglyceride levels [8]. 

Although professionals have encouraged aerobic exercise for improved cardiovascular health for a long time, research also encourages resistance training for heart and vascular health. One study explicitly suggests a combination of moderate-intensity aerobic and moderate- to high-intensity resistance exercise to lower LDL and raise HDL [9]. 

The Impact of Cholesterol Levels on Overall Health Needs More Study

Experts agree that the effects of a low-carb diet on cholesterol and lipids require further study, especially concerning the long-term effects of fad diets like keto. However, studies and analyses in the medical community indicate that low-carb diets may provide therapeutic value to reduce the risk of cardiovascular disease. Many health professionals are considering the value of low-carb vs. low-fat diets. 

Many studies note that cholesterol levels may not accurately predict cardiovascular disease when considered independently. Researchers encourage medical professionals to test for many risk factors to determine a patient’s risk of heart disease, stroke, or another cardiovascular disease.