Healthy Fats: Eating Fat Isn't Wrong, and Understanding HDL and LDL

Many of my patients are so afraid of fat that they cut out anything oily, yet keep eating white rice, bread and sweet drinks as before, so their blood results don't improve. The truth is that the body needs fat, to make hormones, absorb vitamins and nourish the brain. What matters is which "type" we choose and what we eat it "instead of".

Blood fats made simple

LDL

"Bad" cholesterol

• Builds up in artery walls
• Lowering it = fewer heart attacks and strokes

HDL

"Good" cholesterol

• Carries cholesterol back to the liver
• A signal, not a number to push up

Triglycerides

• Raised by sugar, refined starch
• Alcohol, excess weight

Total cholesterol

• A summary figure for context
• Can't be judged alone

A misunderstanding to correct: high HDL doesn't always mean safe

We used to believe that the more you raised HDL, the better for your heart. But large studies of drugs that raise HDL a lot, such as niacin and the CETP inhibitors, did not reduce heart disease, and population studies have found that abnormally high HDL doesn't protect either. HDL is therefore a signal of overall health, not a number to chase upwards.

What has the clearest evidence is lowering LDL, through diet, exercise and medicine when needed, which genuinely reduces the chance of heart attack and stroke.

Where healthy fats come from

1. Oily sea and freshwater fish such as salmon, sardines, mackerel, snakeskin gourami (pla salid) and snakehead fish. Eat fish at least 2 meals a week for omega-3s, which help lower triglycerides.
2. Nuts and seeds: almonds, walnuts, peanuts, pumpkin seeds, sesame; a small handful a day (about 30 g).
3. Vegetable oils high in unsaturated fats: olive oil, canola oil, rice bran oil, soybean oil.
4. Avocado, if you can find it and like it.
5. Soluble fiber: oats, dried beans and apples lower LDL a little, but steadily.

Fats to cut down

• Saturated fat: lard, chicken skin, butter, large amounts of cheese, coconut milk, palm oil and coconut oil can raise LDL. You don't need to cut them to zero, but keep them under 10% of your calories.
• Trans fats from partially hydrogenated oils. Thailand banned their production and import in 2019, but still be careful of food fried repeatedly in old oil.
• Deep-fried food: not just fat, but very high in calories.
• Sugar and refined starch: not fats, but they raise triglycerides and lower HDL.

Choose instead

• Fish, at least 2 meals/week
• A small handful (~30 g) of nuts or seeds daily
• Olive, canola, rice bran, soybean oil
• Soluble fiber: oats, beans

Cut down

• Saturated fat: pork fat, chicken skin, coconut milk
• Trans fat: reused frying oil
• Deep-fried food
• Sugar, refined starch

vs

The principle is to swap, not add, because all fats are high in energy.

Lifestyle changes that help blood fats

• Aerobic exercise of at least 150 minutes a week lowers triglycerides and raises HDL a little.
• Losing 5–10% of body weight improves several blood fats; see Weight-loss pens (GLP-1) for people with a medical indication.
• Quit smoking, which directly damages blood vessels, including those needed for erections; see Vascular causes of ED.
• Limit alcohol, which raises triglycerides.

A Mediterranean-style diet focused on vegetables, fish, nuts and olive oil has evidence from the PREDIMED study that it reduces cardiovascular disease, and it adapts easily to Thai food, such as steamed fish, clear tom yum, gaeng som (sour curry) and stir-fried vegetables with little oil. Read more in Nutrition after 50.

When to test cholesterol, and when you need medicine

Adults should have their blood fats checked from age 20 and then repeat according to risk. These days most people don't need to fast before the test, unless triglycerides are very high or the doctor advises it. See the other recommended tests in Health checkups for working-age adults.

Deciding whether you need cholesterol-lowering medicine isn't based on LDL alone, but on your total risk: age, sex, blood pressure, diabetes, smoking, kidney disease and a family history of early heart disease. If LDL is very high (for example over 190 mg/dL), think about inherited high cholesterol and test family members too.

At Dr. Kris Clinic I help interpret your cholesterol results, assess your cardiovascular risk and plan meals that work in daily life. If you have chest pain or tightness, breathlessness, sudden weakness in an arm or leg or a drooping face, call 1669 (Thailand's medical emergency number) immediately.