Surprising Causes of High Triglycerides. If youâve recently found out that your triglyceride levels (trigs) are elevated, and your healthy diet hasnât helped lower them, read on to find out why. Trigs are lipids (fats) that, in excess, can increase your risk of heart attack or stroke. Eating foods high in sugar, starch or fat can dramatically raise trig levels in your blood. If your trig levels are elevated (a simple blood test can tell), you'll want to cut back on sweet and starchy foods.