Eating food based on the glycemic index helps reduce your risk of chronic health conditions which include type 2 diabetes, heart disease, high blood pressure, allergies...
and more.
Eating mostly low glycemic, high quality carbohydrates will help control your hunger and therefore help you with weight loss.
Usually protein and fat do not increase your blood sugar levels...
but be careful here as maybe they will increase your weight.
The glycemic index rates carbohydrate foods according to how quickly blood sugar levels increase in the two to three hour period after eating carbohydrates.
Low GI foods are rated 0 through 55 on the glycemic index scale.
The scale goes from 0 all the way to 100 although some foods can be higher than 100.
The glycemic index scale is only for carbohydrate foods.
Low GI foods are foods such as:

• vegetables such as celery, tomatoes, spinach, lettuce, artichokes, broccoli, cauliflower, cabbage, radishes, onions, garlic, string beans, okra, carrots and other nonstarchy vegetables
• nuts that don't have any carbohydrates in them such as walnuts, pine nuts, macadamia nuts
• nuts that do have carbohydrates in them, such as cashews and peanuts
• fats such as olive oil which comes from unrefined vegetable sources, safflower, corn and soy oil, and coconut oil
• fruits that are not usually super sweet such as cherries, apples, oranges, berries, and some melons

Even eggs (raw) are classed as a low GI food, as are fish (fresh or frozen), low-fat tofu, skinless turkey breast, veal, skinless chicken breast The reason why these foods can curb your hunger is:

• they do not cause a rapid rise in your blood sugar levels.
  When blood sugar levels rise too fast, insulin comes to the rescue and brings these levels down quickly...
  to the point where you could be in the low blood sugar zone.
  Once you're in this zone, you will get symptoms such as hunger and food cravings.
  

High fiber foods curb hunger by another mechanism: High fiber foods would be foods such as:

• whole grain breads and rolls
• whole grain breakfast cereals such as millet, quinoa, buckwheat, brown rice, and rye

The fiber in these foods prevents a quick release of the sugars in the carbohydrates these foods contain.
The fiber in high fiber foods may also bind up some of the sugar in their chemical composition, making it unavailable to enter your bloodstream.
That's how it works to control your hunger and your blood sugar levels.