How NOT to Approach the Obesity Problem

Abstract

FLATT, JP. How NOT to approach the obesity problem. Obes Res. 1997;5:632433. The emphasis given to the energy balance equation has fostered the widespread belief that obesity is a problem of energy balance. This mistaken view has led to many unjustified and unfortunate interpretations, because obesity is, rather, a problem of the interaction between body composition and food intake regulation. Key words: energy balance, energy expenditure, energy intake, bodyweight regulation, obesityIn addressing the issues of bodyweight regulation and obesity, there seems to be an almost universal habit to first restate the energy balance equation, i.e.:Energy Balance = Energy Intake-Energy Expenditure.The conclusion derived from this consideration is invariably that obesity is due to excessive energy intake andor insufficient energy expenditure. Logically, this leads next to an examination of the various factors influencing energy intake and energy expenditure, . . . and a big mistake has been made in approaching the obesity problem, because the critical issue is not intake or expenditure taken separately, but the adjustment of one to the other under ad libitum food intake conditions.To some extent, this mistake has been provoked by the fact that the variables influencing energy expenditure are more readily studied in humans, whereas food intake regulation is more amenable to study in animals. The reasons for this are that the human subjects volunteering for such studies are willing to submit to the required experimental procedures at the whim of the investigator, i.e., to lie still when resting metabolic rates are to be determined, to consume specified test meals so that the thermic effect of food may be studied, or to exercise at prescribed intensities. Energy expenditure is usually determined by indirect calorimetry, the results of which provide data on carbohydrate, fat, and protein oxidation. Such data are appealing because they offer far more interesting information than merely overall expenditure. Substrate balances can also be obtained, provided that nutrient intake is known accurately, which is most readily accomplished by presetting the amounts of foods to be consumed. It is well nigh impossible, unfortunately, to measure food consumption and its regulation under natural conditions in human subjects, because the amounts and variety of foods consumed under free-living conditions vary greatly from meal to meal and from day to day (l), depending on a multitude of circumstances. Additional complications are caused by the fact that intakes are influenced by individual food preferences and eating patterns, which include weekly and seasonal cycles (6). In animals, on the other hand, food consumption under ad libitum conditions can be readily measured, as can the effects of changes in its composition. In animals, however, 24-hour energy expenditure and substrate oxidation, as well as the factors causing metabolic rates to vary, are not readily established, because activity or inactivity and food consumption at spec...

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