Losing weight without dieting. Use of commercial foods as meal replacements for lunch produces an extended energy deficit

High-protein liquid meal replacements have proven to be effective in reducing caloric intake and body weight. Recently, substituting high fiber breakfast cereals for the more expensive high-protein drinks has been found to be equally effective to reduce weight. The following study tested the hypothesis that the mechanism responsible for the reduced intake was not the dietary composition of the meal replacement, but the controlled portion sized meals. Seventeen volunteers ate all of their meals and snacks from foods provided by the research unit from Monday to Friday for five consecutive weeks. For the first week, all participants selected their food from a buffet where each food was weighed before and after eating. For the next two weeks, half of the group selected their lunch by choosing one food from a selection of six commercially available portion controlled foods. They could eat as much as they wished at other meals or snacks. For final weeks four and five, the conditions were reversed for the two groups. Consuming the portion controlled lunches resulted in about a 250 kcal reduction in energy intake. More importantly, no sign of caloric compensation was evident across the 10 days of testing, an observation substantiated by a significant loss of body weight. The results suggest that the mere substitution of one smaller portioned meal each day is sufficient to cause reduction in daily energy intake and a significant amount of weight.

► Small portion, commercial foods were substituted for regular lunches for 2 weeks.
► The substitution caused a 250 kcal deficit in total daily intake and a weight loss.
► No sign of a compensatory increase in intake was found throughout the test period.
► Results confirm that humans do not regulate energy intake with any precision.
► Small portioned, commercial foods can successfully be used to control body weight.