- A weight tracking site like FitDay. People enter some information about themselves, what they eat every day, and how much they weight. The site lets them track the number of calories they eat along with their weight. Currently, these sites don't make recommendations about what to eat.
- Data mining algorithms.
Once you have over 5 million users on your weight tracking site, perform statistics to find out what actually makes people lose weight – e.g., “by eating one more cup of yogurt every day, you can lose 1lb per month.” As opposed to other diets that are pulled out of somebody’s behind, this one will be based on millions of data points.
Start recommending what to eat.
Alternative (Advanced) Preparation Instructions:
Use collaborative filtering to determine what is the best diet for each individual. By looking at people who have similar profiles to each other (they weight the same, like to eat the same things, etc.), it may be possible to design a diet that works for you personally: “that person who is very similar to you lost weight by doing X.”