A pair of new papers in the Journal of the American Heart Association serves up a fundamental challenge to assumptions about nutritional guidance in obesity. The science is complex, involving metabolomics and dietary quality. But the concept is simple. Obesity is not just a simple problem of excess body fat. Rather, it is a complex disease state. In obesity, metabolic function and the biological response to nutrition can be profoundly altered.

Thus, a single fixed approach to dietary recommendations for persons living with obesity is inadequate. In one of these two new papers, Rajeev Gupta and Anshul Yadav point to the differences in how different persons with obesity respond to what they eat and say:

“Recognizing this heterogeneity calls for precision nutrition strategies tailored to individuals’ unique metabolic phenotypes.”

The Metabolomic Analysis

Autumn Hullings and colleagues conducted a metabolomic analysis of data from the CARDIA cohort. They found that people with obesity differ in the biochemical pathways that link what they eat to disease outcomes.

Even though two people may have the same body-mass index, their internal “metabolic wiring” can be quite different. In some, lipids, amino acids, or other small molecules respond more strongly (or weakly) to certain foods. That means when both eat, say, a high-fat or high-sugar diet, their blood chemistry changes in distinct ways—and those differences influence disease risk (e.g., heart disease or diabetes).
AHA Journals

In plain terms: obesity is not the same metabolic state for everyone. This research implies that diet effects are filtered through each person’s unique metabolome. Two people with obesity might eat the same food and yet one develops harmful changes in blood lipids or inflammation, while the other does not—or does so more slowly. That variability helps explain why one diet may work well for one person but not for another.

Better Guidance Needed

With this in mind, Gupta and Yadav suggest that current nutrition guidance for persons living with obesity reflects a measure of certainty about how to eat healthy that is not warranted.

“Obesity must be reframed, not as a simple behavioral failing, but as a complex, metabolically distinct state requiring tailored interventions.

“Adopting these biologically nuanced frameworks can enhance cardiovascular outcomes, mitigate stigma as a significant barrier to dietary adherence, and align nutritional science with the complexity of human metabolism.”

To be clear, this is an aspiration. Today, what we can say is that we need guidance that fits the unique needs of each person living with obesity. Not that we have all the answers. Instead, professionals must rely on their clinical judgment and skill for listening to the unique needs of each patient.

This is a work in progress.

Click here for the study by Hullings et al and here for the editorial by Gupta and Yadav.

Healthy Food, photograph by the National Cancer Institute / Wikimedia Commons