Faulty. Flawed. Messy. Untrustworthy. The science behind most experts’ advice on diet and health is a popular target these days (thanks, in part, to the food industry). One frequent attack: The advice is based on weak “observational” studies that can’t prove cause and effect. Wrong and wrong. Those types of studies are not necessarily weak, and most advice is also based on randomized clinical trials, the gold standard of scientific research. Here are five game changers.