If you’re trying to lose weight, counting calories matters, but they’re hard to understand. A nutrition professor tries to clear up some of the confusion behind caloric intake and weight gain.

Where They Come From

Marion Nestle, a professor of food studies at New York University, shares her theories on calorie counting. She explains that where your calories come from play a huge part in maintaining your weight and overall health. Whole grains, veggies, and fruits have calories, but they also offer nutrition. You’re also more apt to feel fuller faster, so you’ll eat less.

Calories from sugar are the most harmful to your body. They are also the largest source of “empty” calories. That is, they hold zero nutritional value. There are no vitamins, protein, or fiber. A large cup of soda contains a wealth of sugar and calories, yet it doesn’t “feed” your body. It persuades your body to eat more. When we eat something sweet, we want more of it.

Less is Better

Clearly, the fewer calories you ingest, the more possibility of weight loss—especially if you’re exercising regularly. Nestle warns, however, that even though Chipotle offers more nutritious food, we think we can eat more of it. McDonald’s, she adds, (although unhealthy) they do offer portion control. So, even if you’re eating nutritious foods, some calories you consume still count.

Nestle believes that obesity in America wouldn’t be so rampant if we understood the basic principle of calories. “Larger portions have more calories.” A 20-ounce soft drink can contain up to 300 calories. Think of how much exercise you need to do to work off those empty calories. And you still haven’t even eaten anything.

Best Calories

Enjoying a diet of fresh, unprocessed foods will be your healthiest source of calories. Nestle does not advocate cutting sugar completely out of your food repertoire. Just keep it limited. According to this expert, it’s portion size that will determine your ability to maintain or lose weight.

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