This paper had received a bit of attention on a number of health blogs around the web a few years back, because it provides a theoretical model of how protein intake can both aggravate and alleviate obesity.

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Summary
The obesity epidemic is among the greatest public health challenges facing the modern world. Regarding dietary causes, most emphasis has been on changing patterns of fat and carbohydrate consumption. In contrast, the role of protein has largely been ignored, because (i) it typically comprises only ∼15% of dietary energy, and (ii) protein intake has remained near constant within and across populations throughout the development of the obesity epidemic. We show that, paradoxically, these are precisely the two conditions that potentially provide protein with the leverage both to drive the obesity epidemic through its effects on food intake, and perhaps to assuage it. We formalize this hypothesis in a mathematical model. Some supporting epidemiological, experimental and animal data are presented, and predictions are made for future testing.
Full paper here: http://insects.tamu.edu/reu/articles...hypothesis.pdf

It seems that when animals are able to naturally eat their desired amount of protein intake, their overall self-selected calorie consumption decreases. Conversely, when they cant get enough protein, their over caloric consumption increases in compensation, making them fatter.

However, this isnt a justification per se for a high protein diet, because in nearly all studies of self-selected protein intake among a wide variety of creatures, inc. humans, protein intake fairly reliably comes out at around only the 15% of calories level. There are a number of theories about why self-selected protein intakes are quite low, one being that many creatures instinctively know that high protein intakes reduce longevity Mangan's: The Protein Leverage Hypothesis of Obesity

Another interesting observation on the data in the review paper was that although increased protein intake seems to control calorie consumption in the short term, over the long term the trend drops off, indicating that the appetite-suppressing effects of high protein diets aren't very effective in the long run. ts theorised this is simply because metabolic homeostasis is regained after a while Perfect Health Diet » Protein, Satiety, and Body Composition