Scientists found that using MRI scans to estimate how much energy your body uses at rest is a bit better than just using your weight or body scan data—but it doesn’t help much more in spotting when your metabolism slows down in response to dieting.

We analyzed the available evidence and found that MRI-based models appear to offer a slight edge over body weight or DXA models when estimating resting metabolic rate, but the improvement is small. The evidence we’ve reviewed so far suggests MRI scans provide a more detailed look at body composition—like muscle and fat distribution—which may help refine how much energy the body uses while at rest [1]. However, when it comes to detecting metabolic adaptation—the slowdown in calorie burning that can happen during weight loss—MRI models don’t seem to add meaningful insight beyond simpler methods like weight or DXA scans [1]. This doesn’t mean MRI is useless, but the added complexity and cost don’t clearly translate to better predictions about how metabolism responds to dieting. We’ve seen no studies that contradict this pattern, but the number of assertions reviewed is very limited—only one was analyzed in detail [1]. Because of this, we can’t say whether MRI would perform differently in larger or more diverse groups. The current evidence leans toward MRI offering a marginal benefit for estimating resting energy use, but not for tracking changes during weight loss. For someone trying to understand their metabolism, this means that while advanced imaging might give a slightly more precise number at rest, it likely won’t help you predict or explain why your body burns fewer calories after losing weight. Simple measures like weight and body composition scans still hold strong value.