What’s the Connection Between Cholesterol and a Weight-Loss Diet?

In the United States, overweight and obesity are becoming increasingly prevalent. Often riding in tandem with it is high cholesterol. But what's the link between weight and cholesterol? And will losing weight lower your cholesterol, or could it even raise it?

​Read more:​ The Truth About How Your Diet Affects Your Cholesterol

According to the Centers for Disease Control and Prevention (CDC), obesity-related diseases, including heart disease, Type 2 diabetes and certain cancers, are some of the leading causes of death.

Just over 11 percent of Americans have high cholesterol, according to the CDC, and more than 42 percent of adults are living with obesity, based on the latest CDC data. Each is a leading risk factor for heart disease, the top cause of death in the country, states the CDC. Like high blood pressure, high cholesterol is a sneaky condition. There are no warning signs as it first starts to build up along blood vessel walls.

But the good news is that a loss of just 5 to 10 percent of your total body weight is likely to result in improved blood pressure, sugars and cholesterol, adds the CDC.

"Most of the time when a person loses weight, the levels of LDL, the bad cholesterol, go down," says Roger Blumenthal, MD, a professor of cardiology at Johns Hopkins and director of its Ciccarone Center for the Prevention of Cardiovascular Disease. "This is especially true for people whose triglyceride levels are above average. A good rule of thumb is that if triglyceride levels are high, there's a bigger impact from dietary changes on LDL."

But which diet yields the best results when it comes to improving your cholesterol levels? A study published in September 2014 in the ​Annals of Internal Medicine​ compared the effects of a low-carbohydrate diet and a low-fat diet on body weight and cardiovascular risk factors in nearly 150 people. The results? Participants in the low-carbohydrate diet lost more weight and showed improved cholesterol levels.

More extreme weight-loss measures produced even better results. A September 2019 study published in ​The Lancet​ looked at the effects of a 25 percent calorie-restricted diet over two years on more than 200 healthy adults not living with obesity.

As well as showing mean weight loss of more than 16 pounds in people who followed the low-calorie diet, the results showed a significant reduction in all cardiometabolic risk factors, including improved scores for LDL and HDL cholesterol and blood pressure.

But Dr. Blumenthal warns that a diet high in saturated fats can raise LDL levels regardless of how much weight you lose. "That can be a problem with diets like the Atkins or paleo diet," he says. "Most people who lose weight also improve their dietary choices, eating more fruits and vegetables, for example. But theoretically, if you lose weight on a diet of cheeseburgers and fries, you could raise your LDL." Yes, you can be a skinny person with high cholesterol.

And while Dr. Blumenthal says there are smart people on both sides of the debate between advocates of low-carb and low-fat diets, it's important to keep in mind that all carbohydrates aren't equal. "You have to differentiate between simple and complex carbs," he says. "A healthy diet cuts back on simple carbs like plain pasta, sugar, cakes, pies and white rice. But complex carbs like fruit, vegetables and whole grain can improve cholesterol levels and lower blood pressure."

Dr. Blumenthal also cautions that the link between weight loss and cholesterol is very person- dependent. "Sometimes levels of HDL, the good cholesterol, can go down when a person cuts down on saturated fat," he says. "It's probably genetic."

Even as Dr. Blumenthal recommends a diet rich in fruits, vegetables, fibers and whole grains and low in saturated fats, he concedes that "there are a lot of things we don't know or can't predict about the effect of diet — the science of diet has lagged behind the science of medications."

​Read more:​ How to Find the Best Weight Loss Diet for You