With fall just around the corner, you may already be daydreaming about cozy cashmere sweaters and curling up to a hot and hearty bowl of oatmeal to fend off the morning chill.And chances are, you’d give yourself a big pat on the back for choosing a healthy breakfast option like oatmeal rather than grabbing a fat-filled muffin or buttery bagel. After all, oatmeal has been on a health pedestal for years—and for a good reason. Oatmeal is packed with soluble fiber, which reduces your low-density lipoprotein (LDL), the “bad” cholesterol. In fact, having 1 1/2 cups of cooked oatmeal provides six grams of fiber. It’s also good for diabetics since oatmeal takes a while to digest, preventing unwelcome spikes in blood sugar, and is often recommended by nutritionists for weight loss because it helps keep you feeling full.MORE: Eating Habits to Overcome ObesityThe problem is that some people don’t like the taste of oatmeal but make themselves eat it because they know it’s good for them. And that can backfire. To make it more palatable, they often pile on sugar—or worse, pick up oatmeal at fast food chains like McDonald’s even though they’re full of sugar and additives—knocking the breakfast staple right off its health pedestal.In one study, 1,000 people were asked to follow three small behavior changes, including eating oatmeal for breakfast, every day for three months. Surprisingly, the oatmeal eaters gained weight. So study author Brian Wansink, Ph.D., author of Mindless Eating: Why We Eat More Than We Think wanted to find out why. Turns out, the oatmeal eaters put on extra pounds because they were loading their morning oatmeal with sugar, eating well beyond the recommended portion size of a half cup, or were rewarding themselves with additional calories in the form of a mid-morning snack.In other words, they managed to undo the health benefits of eating oatmeal faster than you can say “instant oatmeal.”QUIZ: What is Your Eating Style?“Oatmeal has a health halo,” says Wansink. “As a result, people think it’s a lot healthier for them than it actually is. Eating it with too much sugar jacks up the calories. So does eating too much.”Adds Wansink, “If you don’t really like the taste of oatmeal, it defeats the purpose of eating it because you’re going to find some other way to compensate, such as putting in a lot of brown sugar to make it a little more palatable. But you can also do that by varying the texture of oatmeal by putting good stuff in it.”RESEARCH: Skipping Breakfast is Associated with Health RisksThe solution: Transform boring oatmeal by adding a touch of sweetness or texture the healthy way—with a small handful of dried fruit, sliced almonds or walnuts, or with flavorful spices such as cinnamon.Or skip it all together. There are plenty of other healthy breakfast options out there.MORE: Heart Healthy Tunisian Egg Scramble