Solid Versus Liquid Calories: Current Scientific Understandings

Abstract

Food form influences food choice, energy intake, and possibly body weight. Expectations and sensory properties related to food form alter behavioral and physiological responses in consumers. Beverages hold weaker appetitive effects and elicit compensatory dietary responses than solid foods. Thirst sensations are stronger and more consistent over the day than hunger sensations. Not all foods high in water content elicit comparable appetitive and compensatory responses; clear beverages are most problematic for promoting positive energy balance and weight gain. Energy-yielding beverage intake increased markedly between the late 1970s and early 2000s then moderated, albeit at a high level. Beverage consumption adds energy to the diet, but it is also associated with increased energy intake from solid foods; causality has yet to be established. The association between beverage and food energy holds across sexes, age, and ethnic groups. The epidemiological data, short-term appetite and feeding studies, randomized controlled trials, and mechanistic findings strongly suggest, but do not confirm, that energy-yielding beverage consumption is directly related to risk of weight gain.