As it turns out, you can eat the right foods, but if you aren’t eating the right portion sizes, you won’t lose weight. A journalism professor weighed in on how to lose weight and keep it off with one simple step.

According to NBC News, Michael Easter, a journalism professor, complained that his knees hurt after running. He wasn’t overweight as he was just over six foot tall and topped the scales at 185 at his heaviest. The Las Vegas resident believed that if he shed a little weight, his pain wouldn’t be as severe after working out.

Easter’s nutritionist advised him to weigh all his food for at least a week, just to make sure his portion sizes are accurate. Michael was shocked when he discovered he was consuming about four times as many calories as he initially believed.

He revealed that he had the same lunch every day. He believed it was a healthy meal, but he discovered that he was eating three servings instead of one. So instead of eating 200 calories, he was actually eating just over 600 calories.

Easter decided to buy a small kitchen scale he found at his local Target for $14 and began weighing all his foods and drinks, including his morning coffee. He downloaded the MyFitnessPal app on his phone and calculated how many calories he should consume.

Don’t be afraid to weigh your food. It’s so easy to overestimate a portion and eat too much… & it makes all the difference #food #portion

— Stripped Fitness (@strippedfitness) January 31, 2017

He thought he was eating, at the most 2700 calories per day. After a week logging and weighing his foods, he learned that he actually was consuming over 3,500 calories.

Michael explained that dieters make assumptions on portion sizes. For example, filling your bowl with cereal and milk, instead of using a measuring cup.

Easter added that he has a bad habit of grabbing a handful of nuts and just assuming it was one serving. After weighing his foods, he realizes he was off by 100-200 calories when he didn’t accurately weigh his foods.

You gotta weigh, weigh, weigh, weigh… Honestly, weigh your food to best understand how m…

— Ryan Bretag ⚓ (@ryanbretag) July 5, 2016

The 30-year-old found that if he stuck to meats, vegetables, potatoes, and nuts helped him stay full in between meals and less likely to binge. He felt that eating potatoes helped keep him satisfied and less hungry in general.

After weighing all his foods and finding the right amount of calories to consume, he lost 10 pounds in three months.

Do you weigh your foods? Does it help you shed weight versus just eating a healthy diet? Share your opinion in the comments section below.