Is Obesity a Healthy Active Response to an Expected Future Lack of Energy rather than a Passive Storage of Surplus Energy?

The thermodynamic laws provide an exact quantitative description of obesity as a reflection of a cumulative surplus of energy intake relative to energy expenditure [1] . The prevailing interpretation of this physical truth is that the process of accumulation of fat is a passive storage of the surplus of energy caused by an energy intake that exceeds the expenditure [2, 3] . This is a core assumption in the conventional concept of the obesogenic environment as being responsible for the obesity epidemic; the increasing exposure to energydense, palatable and cheap foods and drinks together with a variety of practical tools minimising demands of physical activity is assumed to make individuals gain weight, and most so those who suffer from genetically or environmentally programmed susceptibility [3, 4] . Although experimental manipulation can enforce a positive and negative energy balance and, not surprisingly, can induce the predicted change in energy stores, including fat stores [2] , naive extrapolation of this evidence to the understanding of the causes of obesity may turn out to be a serious mistake [3] . This may be the reason why we generally have failed in both preventing and treating obesity effectively. There are several reasons why the naive interpretation of the cumulative positive energy balance is inadequate in the understanding of the development of obesity [2] . The quantity of fat accumulated per day is on average so small that measurement of it is beyond any available technique. Measurement while the accumulation is on-going would, had it been possible, just confirm the physical truth, from which we learn nothing new. A distinction between increase in intake and/or decline in expenditure as the initiating process would in theory be possible; however, in practice it would be impossible, also because of uncertainty about the timing of the initiation. Accumulation of fat could easily take place without an Received: May 3, 2012 Accepted: May 4, 2012 Published online: June 27, 2012