"The Big Three" properties of food that drive intake.

Much of the interest in studying human eating behavior stems from a desire to characterize properties of foods that affect consumption, with the goal of leveraging influential properties to moderate energy intake. We propose that established determinants of intake include "The Big Three": portion size, energy density, and variety. Over the past several decades, multiple studies have demonstrated a causal relationship between portion size and intake across different participants, settings, and contexts. The robust effect of portion size can be leveraged to moderate intake by increasing the proportion of low-energy-dense dietary components available. Among "The Big Three", energy density likely plays the most dominant role. Even small reductions in energy density, such as increasing the water content of foods, can lead to reductions in energy intake, and, over time, body weight. In addition, increased food variety can delay satiation by countering the relative hedonic decline of a food as it is consumed (sensory-specific satiety). As a result, exposure to a greater variety of foods increases intake, especially when the sensory properties of the foods served differ from one another. "The Big Three" characterize the current food environment, which is filled with a wide variety of food options, many of which are energy-dense and large in portion size. This review covers early studies assessing the effects of these three food properties on satiation, introduces recent studies, and discusses how this understanding can be applied to moderating energy intake.