Blood and Urine Tests Expose Junk Food Habits, Link to Health Risks

Scientists have cracked the code on spotting junk food junkies with a simple blood or urine test. A groundbreaking study from the National Institutes of Health (NIH) reveals that these tests can pinpoint just how much ultraprocessed food—think Twinkies, soda, and frozen pizzas—someone’s been scarfing down. Using machine learning, researchers identified hundreds of metabolites, those tiny molecular footprints left by metabolism, that scream, "I ate chips!"

The team, led by Erikka Loftfield, Ph.D., from the National Cancer Institute, developed a biomarker score to track ultraprocessed food intake. They analyzed samples from 718 older adults who spilled the beans (and maybe some ketchup) about their diets over a year. Then, in a smaller trial, 20 adults alternated between two weeks of junk food feasts and two weeks of cleaner eating. The results? Blood and urine don’t lie, even if your food diary does.

Published in PLOS Medicine, the findings show these metabolites tie directly to ultraprocessed food consumption, which is often loaded with calories but skimpy on nutrients. This matters because diets heavy in these foods are linked to obesity, chronic diseases, and even cancer. Unlike self-reported food logs, which can be as reliable as a politician’s promise, these tests offer hard evidence. But hold the fries—the method needs more tweaking before it’s ready for prime time, especially across different ages and diets.

Loftfield suggests checking Nutrition Facts labels to dodge foods high in sugar, fat, or sodium—a solid step toward healthier eating. This discovery could revolutionize how we study diet’s role in disease, shining a spotlight on the sneaky impact of processed snacks.