Like most online diet sites, Diet.com has a free diet profile that includes a personality quiz from Dr. Robert Kushner, a board certified physician in internal medicine and nutrition. Based on the results of the diagnostic quiz, Diet.com is able to create a weight loss program targeted to the member's wants and needs.

Based on the personality quiz, dieters are broken down into seven types of eaters.

- Meal Skipper - Eating without focusing on what or when you are eating.
- Nighttime Nibbler - Eating most of your daily food at night.
- Convenient Diner - Eating convenience foods rather than fresh foods.
- Fruitless Feaster - Enjoying a meat and potato diet without veggies and fruit.
- Steady Snacker - Hungry or not, Snacking throughout the day.
- Hearty Portioner - Enjoying portions that are too big for your needs.
- Swing Eater - Eating "good" in public and "bad" alone.