The First Year Of GLP-1 Use Comes With This Hard-To-Detect Side Effect

GLP-1 medications have become one of the most talked-about tools in metabolic health. They curb appetite, help regulate blood sugar, and have shown real results for weight management, so much so that GLP-1 medications just got WHO backing for obesity treatment.

But as more people start these medications, some side effects are coming into light. A recent study published in The Journal of Nutrition1 found that people in their first year on GLP-1s may be falling short on several key nutrients, and most people don't see it coming.

GLP-1s, appetite & nutrition

GLP-1 receptor agonists work by slowing digestion and reducing appetite, which leads to lower overall food intake. For this study, researchers wanted to understand whether that reduction in eating was also affecting nutritional quality, and whether it mattered how long someone had been on the medication.

Using NHANES data collected between 2007 and 2020, they looked at adults with type 2 diabetes and divided them into three groups:

They then compared each group's likelihood of meeting recommended daily intake levels for key nutrients.

Because this was a cross-sectional study (meaning it captured a single point in time rather than tracking people over months or years), the findings show an association between short-term GLP-1 use and lower nutrient intake, not a direct cause-and-effect relationship.

Short-term users were significantly less likely to hit daily targets for five nutrients

Compared to non-users, short-term GLP-1 users were significantly less likely to be meeting recommended daily intake levels for folate, iron, niacin, potassium, and vitamin B6. Long-term users, on the other hand, showed eating patterns that looked much more similar to people not on the medication at all, suggesting that over time, many people naturally adjust how they eat.

Why the first year carries the biggest risk

Why is the first year of using these medications so different? GLP-1 medications reduce appetite significantly, which means people eat less overall. And when you eat less overall, you tend to eat less of everything, including the foods that supply key vitamins and minerals. GLP-1s are unique in how quickly and dramatically appetite can decrease, often faster than a person's ability to consciously shift toward more nutrient-dense foods.

Long-term users appeared to develop eating habits that more closely resembled people not on the medication, suggesting that many people naturally recalibrate over time, gravitating toward more nutrient-dense foods or settling into new meal rhythms. But that adaptation takes time, and the first year is when the gap is most pronounced.

It's also worth knowing that nutrition isn't the only thing to monitor in year one. Research suggests unexpected bone health effects from GLP-1 medications, and reduced movement on GLP-1s is another underreported concern. Staying on top of your nutrition fits into a broader picture of proactive care during this period.

How to close the nutrient gap in your first year on GLP-1s

If you're in your first year on a GLP-1 medication, a few proactive steps can make a real difference.

The takeaway

This recent study found that short-term GLP-1 users are significantly less likely to be getting enough folate, iron, niacin, potassium, and vitamin B6, with the risk concentrated in the first year of use. The study was cross-sectional and the short-term user group was small, so more research is needed, but the signal is clear enough to act on.

Proactive monitoring, a focus on nutrient-dense eating, and a conversation with your doctor can go a long way toward closing that gap.