If you're an adult in the Mediterranean region and eat nuts at least twice a week, you're less likely to gain 5 kilograms or more over about two years compared to people who hardly ever eat nuts—even when accounting for things like how active you are or whether you smoke.

What we've found so far is that eating nuts at least twice a week may be linked to less weight gain in Mediterranean adults. The evidence we've reviewed leans toward this pattern. Our analysis of the available research shows that adults in the Mediterranean region who eat nuts at least twice a week are less likely to gain 5 kilograms or more over about two years, compared to those who rarely eat nuts [1]. This observation held even when accounting for factors like physical activity levels and smoking status [1]. We based this on 52 supporting assertions, with no studies or data points in our review indicating the opposite effect [1]. It’s important to note that our current analysis only includes evidence specific to Mediterranean adults. We cannot say whether this applies to other populations, or whether the same results would occur in shorter or longer time frames. Also, while the evidence consistently supports this link across the assertions we reviewed, we are not concluding that eating nuts directly leads to less weight gain—we are only reporting what the data we analyzed shows. We don’t yet know which types of nuts may play a role, how portion sizes might matter, or whether other diet and lifestyle habits interact with nut consumption in these results. Since all the assertions we reviewed support this link and none refute it, the evidence we've examined so far points in one direction—but that doesn’t rule out complexity we haven’t captured. Practical takeaway: If you're an adult in the Mediterranean region, regularly eating nuts as part of your diet might be associated with a lower chance of gaining a noticeable amount of weight over two years.