Sometimes, a meta-analysis (quantitative study of studies) is just what the doctor ordered to inoculate us against the shortcomings of our own cognition. When a topic has been studied extensively and it has produced many studies of varying quality, this lends itself to incorrect conclusions because we can find studies to support almost any belief. This is problematic because we naturally tend to gravitate toward evidence that reinforces pre-existing beliefs, and away from evidence that challenges beliefs. Called confirmation bias, this phenomenon afflicts all of us and has to be actively managed if we want to arrive at reliable knowledge. Systematically examining a body of evidence and integrating it mathematically is a useful tool for combating this bias. A new meta-analysis examines the effect of carbohydrate vs. fat calories on energy expenditure and body fatness, giving us the most objective view of this question to date.