How many people were part of the study? 

If the study is based on other studies, how big were the groups studied in those. 

Was the information collected reliable? Often studies need people to reliably recall how much they ate, what foods they ate and when they ate. 

Is the study saying X causes Y. Or that we noticed that whenever X is there, Y is also sometimes there. U,V and W also matter. But we can’t tell how it all ties together yet. Or how much much each seems to matter. 

If it’s saying X causes Y, do they know how X causes Y. Or are they saying people with X inevitably get Y. We don’t know how yet. 

Are the people in the study representative of how people normally behave? 

Do things like the portion sizes, food chosen and habits studied approximate real world behaviour? 

Is it a study on humans? 

Are the people being studied kind of like you? Not always relevant. But when the effects of exercise is being studied. Age, height, sex, training experience all matter. 

Did the person giving you advice based on the paper read the full paper? 

Who paid for the study? This sometimes affects the takeaway. But not always. 

Have you picked a study that justifies/suits your agenda, bias, practice or habits ?