I actually read the entire thing, and I am posting a summary for those who are too impatient (it's a rather long article) or those who are having problems understanding it.
This study involved a group of 84 women (there were more, but some dropped out before finishing the study). Of those 84, 7 had bulimia nervosa, and 11 had BED. The rest were control subjects. The women kept track of their intake and their binges for one week (called the baseline week). During that week, the average number of OBEs (objective bulimic episodes, i.e. "technical" binges) was about 3, and the average number of SBEs (smaller binges or meals/snacks that the women called binges) was 4-5.
Then, the women got 2 weeks of high-protein liquid supplements followed by 2 weeks of high-carbohydrate liquid supplements, which they consumed before meals. The two-week periods were separated by a "washout" week. Both supplements were 280 calories each. The protein supplements contained 53 grams of protein and 8 grams of carbohydrates. The carbohydrate supplements contained no protein at all and 68 grams of carbohydrates.
The women ate fewer calories at dinner after eating "protein lunches" that were 943 kcal and after eating mixed lunches (both protein and carbs) that were 1,034 kcal than they did after they ate "carbohydrate lunches" that were 1,239 kcal. So, protein has an effect of making you feel full even when mixed with carbs.
At the end of each two-week period, the women were given another supplement (of whatever type they had been getting that week) and then three hours later were taken into a room that had a buffet of all kinds of food. They were told to eat whatever they wanted, however much they wanted, and to take all the time they needed. The participants ate less food after having the protein supplement (their buffet meals ranged from about 200 calories to 1100) than after having the carbohydrate supplement (where their meals ranged from 300 calories to 1400 calories).
The study noted that people with bulimia (or BED) either have a "skewed perception" of being full, or their bodies really don't feel full like normal people's do, because patients with bulimia reported feeling less full than the control subjects did when asked both 5 and 45 min after eating.
One reason that people binge could be that their daily diets are significantly lower in protein. The article said that "the proportion of total energy from protein intake has been shown to be lower for women with BN than for controls." Binges are typically very high in carbohydrates and very low in protein. Also, the bulimic women in this study were found to begin binge episodes AND meals by starting with desserts and snack foods before eating their fish and meat, whereas the control subjects started their meals off by eating their meat.
The women with BED ate more protein on non-binge days than during binge episodes. The article also suggests that individuals with bulimia or BED may not eat enough protein daily, or they may need even more protein than the average person in order for the binge-preventing "protein effect" to occur.
The women had 62% fewer binges during the 2-week period of protein supplementation than during the 2-week period of carbohydrate supplementation. Only the protein supplements were found to be effective in reducing binge frequency. During the two weeks of carb supplements, the average amount of OBEs was still around 3 per week, and the average amount of SBEs per week was 4. Both of those numbers are the same as the number of binges during the baseline week.
Another interesting point was that (I think this part may have come from another study, but I'm not sure) a 1,200-kcal diet that contained 45 g of protein daily led patients to report being a whole lot hungrier and a lot more worried about eating than did a 500-kcal diet that contained between 60 and 75 g of protein daily. So you can actually feel FULLER by eating a lower-calorie diet that is higher in protein than by eating more calories but less protein. It sounds so backwards, but the key element is protein.
If you are curious about the "how your body works" logic behind this, protein is one of the most potent stimulants of cholecystokinin, which is a chemical found to reduce food intake in humans. Also, the level of pancreatic glucagon, which is a hormone shown to help you feel full, increases dramatically in your blood after you eat a protein meal, but actually decreases after a carbohydrate meal. So, carbohydrates could actually make you hungrier!
OK, I know the summary was about as long as the article! Whoops! But hopefully my summary is a lot easier to understand.