For people who want to eat and drink more healthfully, keeping a food journal can be extremely effective. For instance, one study showed that dieters who kept a food journal six or seven days a week lost twice as much weight as people who did so once a week or not at all. Although keeping a food journal sounds straightforward, I braced myself for a challenge when I decided to try it. No one ever mentions how hard it is to keep a food journal, but I'd already tried and failed three times.