The weight of evidence indicates that the primary driver of the obesity epidemic in recent decades has been increased intake, rather than decreased energy expenditure. Not surprisingly, much research has focused on the source of these extra calories, with vigorous debate over whether fats or carbohydrates (especially refined sugar) are the main culprits.
But this approach misses a fundamental point. The obesity problem is best understood not as the result of the overconsumption of a single macronutrient, but from a skewing of the proportion of each macronutrient in our diet — notably the dwindling quantity of protein in processed food products. The paucity of protein relative to fats and carbohydrates in processed foods drives the overconsumption of total energy as our bodies seek to maintain a target level of protein intake.