Studying a nutrition label can quickly get confusing. If there’s saturated fat, does that automatically mean it’s bad for you? How much fiber do you need? And protein? It’s easy to get overwhelmed—but according to Beth Czerwony, MS, RD, CSOWM, LD, registered dietitian at the Cleveland Clinic, there’s one detail you need to pay attention to above all else.

“The biggest thing is looking at the portion size,” Czerwony says. The other numerical figures will just snowball if you don’t portion your plate according to the product’s suggested serving size.

Other helpful guides are carbohydrates, specifically fiber, along protein and fat. Czerwony says when it comes to fiber, “the more, the better,” and that we all should avoid trans or saturated fats as much as possible.

People with certain health concerns should also pay attention to specific figures on nutrition labels. For those with diabetes, Czerwony says the added sugars and carbohydrate fields are important. For anyone trying to shed weight, calorie intake can be a helpful guide. Based on your health, it may be helpful to establish whichever parameters are appropriate, based on conversations with your doctor.

“Sometimes you have to make compromises, sometimes you have to make the best decision based on what that food is and what’s available,” Czerwony says. “But, over time as you become more proficient in it, and you have a better idea of certain brands and certain stores, it’s going to be a little easier. In the very beginning, it does take a little bit of time and a little bit of investigation to know what you’re looking for.”

And lately, if you’ve noticed that more groceries appear with two sets of nutrition facts, Czerwony doesn’t blame you if it’s caused a double-take. “Food labels have morphed over time, so you may see two food labels on the back of a package,” she says, breaking it down: “One is for the entire package, and one is for that actual serving.”

If you’re unsure about which numbers on a nutritional label are most pertinent to your needs, Czerwony recommends speaking with a dietitian who can help you develop a nutrition plan. What’s the difference between a dietitian and a nutritionist? The Cleveland Clinic explains that dietitians tend to go through more extensive and specialized training than a nutritionist. While many nutritionists are highly trained, the requirements for dietitians are usually based on a higher standard. It takes months of clinical practicum training and a degree to gain dietetics accreditation.

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