Some people have a lot of difficulty sticking to a diet, but they must eat the right foods to stay strong and reach their goals. Foods that have lots of protein and fat work great for dieters. The body needs both of these nutrients, but they also leave those who eat them feeling full. That means snacking less and maintaining body weight better by eating the proper foods.BeansBeans have very little fat but have a lot of protein. Black beans, kidney beans and lima beans all have similar nutritional values, containing 15 grams of fiber and 15 grams of protein per-serving. Dieters should mix some of these with their rice to fill up fast. Lentils have similar properties to beans, but have even more fiber and protein.Dieters should consider adding beans or lentils to their soup, omelet or wrap. They have lots of fiber and protein and can help dieters feel full faster. Great whole grainsQuinoa is a South American grain that contains five grams of fiber and eight grams of protein per cup. Oatmeal is also a great choice as it contains both soluble and insoluble fiber, which makes it great for lowering cholesterol and promoting a healthy weight. Dieters also cook oatmeal in water. Cooking in water makes the oatmeal even more filling.Make good choices overallTo diet healthily, dieters have to make all of their choices good ones. Eating oatmeal and beans for every meal is impossible, but dieters can easily choose between the available foods that have the most fiber and protein. To stay healthy, dieters should look for whole grain items, especially when choosing bread, crackers and cereals.When dieters never feel full, they cannot lose weight. Including these high protein, high fiber foods in one's diet can help address this issue and speed up their weight loss.