A study in mice found that weight loss restored healthy metabolism in both young and middle-aged animals[1]. In middle-aged animals, however, weight loss increased inflammation in parts of the brain associated with appetite and energy balance[1]. This increased brain inflammation eventually subsided, but was associated with a decline in cognitive function in middle-aged mice[1]. The authors note that inflammation in these brain regions is also associated with neurodegenerative diseases[1]. Thus, the results suggest that the effects of weight loss on the brain may vary by age and that weight loss in middle age may not only confer metabolic benefits[1]. Therefore, the main finding of the study is that although weight loss improves metabolism in middle age, at the same time it may temporarily worsen brain inflammation and cognitive function in middle-aged individuals[1].