If you're overweight and have metabolic health issues, eating walnuts or cashews for 8 weeks might help your body, but if you don't lose weight, those benefits could be hidden.

What we've found so far suggests that eating walnuts or cashews for 8 weeks may offer metabolic benefits to obese adults with poor metabolic health, even if their weight stays the same [1]. However, those benefits might not be easily seen or measured if weight loss doesn’t occur [1]. Our analysis of the available research shows that maintaining body weight during a walnut or cashew diet could mask underlying improvements in how the body processes energy and manages blood sugar, insulin, or cholesterol levels [1]. In other words, the body might be responding positively to the nutrients in these nuts, but without weight change, those changes may go unnoticed in standard health checks [1]. The evidence we've reviewed leans toward the idea that metabolic health can improve independently of weight loss when walnuts or cashews are added to the diet for at least 8 weeks [1]. This doesn’t mean weight is unimportant—it just means that health changes can happen even when the scale doesn’t move [1]. Right now, we only have one analyzed assertion, supported by 48.0 studies, with no studies refuting it [1]. While the number of supporting studies appears high, we don’t have details on the quality, design, or populations of those studies, so we must be cautious in how far we extend these findings. Still, what we’ve seen so far points to a possible disconnect between visible weight change and internal metabolic progress. We don’t yet know how strong or lasting these hidden benefits are, or whether they lead to better long-term health outcomes. More data would help us understand whether these effects are consistent across different people and diets. Practical takeaway: If you're eating walnuts or cashews regularly and not losing weight, that doesn’t necessarily mean nothing good is happening inside your body—some benefits might just be invisible.