Food diary

A food diary is a simple record of what you eat and drink – and one of the best-studied tools for losing weight. Not because writing things down burns calories, but because it sharpens your self-awareness. Many people significantly underestimate how much they eat; the little bites in between, the splash of cream, the second glass of juice vanish from memory – but not from the energy balance.

In a large US study with almost 1,700 participants (Hollis and colleagues, 2008), people who kept a daily food record lost about twice as much weight as those who kept none at all. A review (Burke and colleagues, 2011) confirms it: regular self-monitoring is consistently linked to greater weight-loss success. The main reason is attention – when you write things down, you reach for food less automatically.

Here's how to make it work: write things down straight after eating, not in the evening from memory. Besides the what, note the when, the where and – the most important column – how you're feeling. After two weeks you'll spot patterns: the 4 pm craving, nibbling while cooking, the big portions on stressful days. Whether you use paper, a notes app or a photo of your plate doesn't matter; the best method is the one you stick with. And remember: it's a tool for two to four weeks, not a lifelong obligation.

One important limit: if keeping the diary becomes compulsive, if you weigh every bite or dread making an entry, it's time to stop and talk to someone – your GP, for example, or anonymously via the telephone advice line of the German Federal Institute for Public Health (BIÖG, formerly BZgA) on 0221 892031. Calorie diaries aren't suitable for children and teenagers because they shift the focus to numbers instead of hunger and enjoyment. A family-friendly alternative is a feel-good diary: what colourful foods did we eat today, how much did we move, how well did we sleep?