Your Blood Betrays Your Junk Food Habits, NIH Study Finds

Your blood might be spilling the beans on your snack habits. New research from the National Institutes of Health (NIH) shows that blood and urine tests can pinpoint how much ultraprocessed food (UPF) you’re eating, thanks to a clever biomarker score developed by scientists. Using machine learning, researchers identified hundreds of metabolites—those tiny molecules produced during metabolism—that scream, "You ate a Twinkie!" or whatever processed treat you’re sneaking.

The study, led by Erikka Loftfield, Ph.D., M.P.H., from the National Cancer Institute, analyzed data from 718 older adults who shared their dietary habits and provided samples over a year. Then, in a smaller trial, 20 adults alternated between two weeks of chowing down on UPFs and two weeks of avoiding them. The results? Hundreds of metabolites in blood and urine were tied to UPF intake, revealing just how deeply these foods mess with your body’s chemistry.

Published in PLOS Medicine, the findings highlight how these tests could replace self-reported food diaries, which are often as reliable as a politician’s promise. UPFs—think ready-to-eat, calorie-packed, nutrient-poor snacks—are linked to obesity, chronic diseases, and even cancer. But the researchers warn that this method needs more testing across diverse diets and age groups before it’s ready for prime time.

Loftfield’s advice? Check those nutrition labels and steer clear of foods loaded with added sugars, saturated fats, and sodium. It’s a simple way to cut back on UPFs and keep your blood from tattling on you.