Many things can raise your cholesterol, from the foods you eat to conditions you may not even know you have. Some causes are within your control, like diet and exercise habits, while others involve genetics, hormones, or medications you need for other health problems. Understanding what drives cholesterol up helps you figure out where to focus.
Saturated Fat and Trans Fat
Saturated fat is the single most well-known dietary driver of high cholesterol. It works by slowing down your liver’s ability to pull LDL (“bad” cholesterol) out of your bloodstream. Normally, your liver has receptors that grab LDL particles and clear them. Saturated fat dials down the activity of those receptors, so LDL accumulates in your blood instead. Major sources include red meat, butter, cheese, full-fat dairy, and coconut oil.
Trans fats are even worse because they hit cholesterol from both directions. In a landmark study published in the New England Journal of Medicine, people eating trans fats saw their LDL rise by about 14 mg/dL while their HDL (“good” cholesterol) dropped by about 7 mg/dL compared to a diet with healthier fats. That simultaneous shift, higher LDL and lower HDL, is an especially risky combination. Trans fats have been largely banned from processed foods in many countries, but they still show up in some imported products, fried foods, and anything listing “partially hydrogenated oil” on the label.
Sugar and Refined Carbohydrates
Most people associate cholesterol with fatty foods, but sugar plays a significant and underappreciated role. When you consume a lot of fructose (from table sugar, high-fructose corn syrup, or sweetened drinks), your liver converts it into fat through a process called de novo lipogenesis. The first breakdown product of fructose in the liver acts as a signaling molecule that ramps up fat production. Once the liver’s storage capacity is full, it packages those fats into particles called VLDL and ships them into your bloodstream, raising both triglycerides and LDL cholesterol.
This effect is amplified when fructose and glucose are consumed together, which is exactly what happens with regular sugar and most sweetened foods. The combination accelerates the liver’s fat-making machinery beyond what either sugar would trigger alone. Sodas, fruit juices, pastries, and candy are common culprits.
Being Sedentary
Physical inactivity doesn’t just contribute to weight gain. It directly impairs how your body processes fats. Your skeletal muscles produce an enzyme called lipoprotein lipase that helps break down triglycerides and supports healthy HDL levels. When you sit for long stretches and rarely exercise, your muscles produce less of this enzyme, and lipid metabolism slows down. The result is lower HDL and higher circulating triglycerides. This effect kicks in quickly with inactivity, not just after months of a sedentary lifestyle.
Excess Weight and Fatty Liver
Carrying extra weight, especially around the midsection, tends to push cholesterol numbers in the wrong direction. One major reason is its connection to fatty liver disease. Nonalcoholic fatty liver disease (NAFLD) is now one of the most common liver conditions worldwide, and its hallmark lipid pattern is high triglycerides, high LDL, and low HDL. A fatty liver also produces more oxidized LDL, a particularly harmful form that accelerates artery damage. Over time, the excess fat in liver cells ramps up the production of cholesterol and triglyceride-rich particles, creating a self-reinforcing cycle of worsening blood lipids.
Chronic Stress
Stress raises cholesterol through a less obvious pathway. When you’re chronically stressed, your body produces more cortisol, the primary stress hormone. Cortisol is actually built from cholesterol, so your body increases cholesterol production to keep up with demand. At the cellular level, chronic inflammation triggered by stress activates a signaling pathway (NF-κB) that removes the normal brakes on cholesterol synthesis in the liver. This leads to increased production of a key enzyme in cholesterol manufacturing, essentially leaving the factory running with no off switch. People under prolonged psychological stress consistently show worse lipid profiles than those who aren’t, even when diet and exercise are similar.
Menopause and Hormonal Shifts
Estrogen helps keep LDL in check and HDL levels healthy. When estrogen declines during menopause, that protection fades. Postmenopausal women typically see their LDL cholesterol rise by 10 to 15%, with triglycerides climbing and HDL dropping at the same time. This shift happens relatively quickly during the menopausal transition and is one reason cardiovascular risk rises sharply for women after menopause, even in those who previously had excellent cholesterol numbers.
Underactive Thyroid
Hypothyroidism is one of the most common medical causes of high cholesterol, and it’s frequently overlooked. Thyroid hormones help regulate how quickly your liver clears LDL from the blood. When thyroid function drops, even modestly, LDL receptor activity slows down and your liver simultaneously produces more cholesterol. The result can be a significant jump in total and LDL cholesterol. Both full-blown and mild (subclinical) hypothyroidism can cause this. If your cholesterol is newly elevated and doesn’t respond well to diet changes, a simple thyroid blood test can rule this out.
Certain Medications
Several commonly prescribed medications raise cholesterol as a side effect. The most notable include:
- Corticosteroids (prednisone and similar drugs): High doses tend to increase LDL, triglycerides, and HDL. Low doses often have minimal effects on lipids.
- Thiazide diuretics: Often prescribed for high blood pressure, high doses can raise LDL by about 10% and triglycerides by 5 to 15%.
- Loop diuretics: Similar to thiazides, these can increase LDL and triglycerides, though sometimes to a lesser degree.
- Retinoids (isotretinoin): Used for severe acne, these can raise LDL by around 15% and triglycerides by 35 to 100%, which is why regular blood work is required during treatment.
If you’re taking any of these and notice your cholesterol climbing, it’s worth discussing with the prescribing doctor. In many cases, the benefit of the medication outweighs the lipid changes, but monitoring matters.
Alcohol
Moderate alcohol consumption is sometimes framed as heart-friendly, but its effect on lipids is more complicated. Even moderate amounts of alcohol can raise triglyceride levels in fasting individuals. Higher intake, generally above two to three drinks per day, reliably pushes triglycerides up further. For people who already have elevated triglycerides, even small amounts of alcohol can make the problem significantly worse. Alcohol is processed by the liver, and the metabolic burden competes with normal fat processing, leading to increased VLDL output.
Genetics and Family History
Some people do everything right and still have high cholesterol. Familial hypercholesterolemia is the most well-known genetic cause, affecting roughly 1 in 313 people worldwide, which translates to over 30 million people. The inherited form involves a defective gene for LDL receptors, meaning the liver can’t efficiently clear LDL from the blood no matter how clean the diet. People with this condition often have LDL levels above 190 mg/dL from a young age. Beyond this specific condition, many common genetic variants can modestly influence cholesterol levels, which is why family history remains one of the strongest predictors of your own lipid profile.