A great many more people, however, would benefit from having some protein at every meal, no matter what they combine it with. The reason for this is that protein helps balance blood sugar levels, which affect energy, mood and weight. Meals low in or devoid of protein and high in carbohydrates are more likely to leave your energy and mood in tatters, and over time are also likely to encourage weight gain. But ultimately, we are all very different, so it' s a matter of working out which diet is best for you.