A "concept map" is a diagram that helps visualize the relationship between concepts or topics.  The image above shows what topics are related to the subject of dieting.

Quite helpfully, the concept map on dieting lays out various common diets that you will encounter when you research weight loss diets, such as: low-carbohydrate diet or low-carb diet, very low-calorie diet, Atkins diet, Western pattern diet, Mediterranean diet, Ketogenic diet, South Beach Diet, Okinawa diet, Zone diet, Weight Watchers (diet), low-fat diet, diabetic diet, and Montignac diet.

You can also see that there are typical diseased and medical conditions listed in topics related to dieting: Obesity, diabetes, and weight gain.

Many diet and nutrition related topics are shown, which you'd have to familiarize yourself with in your research: glycemic index, glycemic load, energy homeostasis, saturated fat, and basal metabolic rate.

Interesting to note are some fasting options, protein-sparing modified fast, and intermittent fasting.

Sometimes, a concept map, such as this one for dieting, is very useful to get a big picture view of the knowledge landscape of that topic.  It can be useful in navigating unfamiliar or complex topics to start with.