The current paradigm suggests that fat people are lazy and greedy and this is why they gain weight. This ‘eat-too-much, do-too-little’ theory of weight gain states that a positive energy balance, caused by too much food or too much little exercise, results in adipose tissue accumulation. However, evidence from the literature does not support this contention. For example, researchers1 have measured the energy intakes of obese women and compared them to the energy intakes of lean controls. The results showed that the obese women had a mean energy intake of 2419 kcal per day, whereas the energy intake of the lean women was 2123 kcal per day. It could be assumed from this that the obese women were overeating because there was an association between energy intake and body weight. However, when the researchers analysed the energy expenditure of the women, they found that the obese women had significantly higher resting metabolic rates (RMR).
The researchers concluded that the energy balance of the obese and lean women was close to zero. This suggests that the obese women were eating more calories because their RMR was higher and therefore required more energy to maintain body weight. This does not fit with the ‘eat-too-much, do-too-little’ theory of obesity and weight gain. The higher energy utilisation by the obese women is explainable by the higher levels of lean mass present in these individuals. The lean mass of the non-obese women was 44.7 kg, whereas that of the obese women was 51.9 kg. Therefore the obese women had 79 % more fat mass, but 21 % more lean mass, compared to the non-obese women. The higher lean mass of the obese women was reflected in greater creatinine excretion, which could not be accounted for by increased meat intake. Therefore the higher RMR of the obese women negated any excess energy intake from the diet and resulted in zero energy balance.
When taken out of context, and ignoring higher energy expenditures, the association between higher energy intakes and body weight appears to support the ‘eat-too-much, do-too-little’ theory of obesity. However, in this study the energy balance was close to zero for both groups. Therefore, that obese individuals have positive energy balances is contentious and not supported by the observable data. The weight gain experienced by the study participants was therefore likely driven by factors other than greed or laziness. That a positive energy balance is not the cause of weight gain is also supported by the almost total failure of forced calories restriction to cause weight loss in obese individuals over the long-term. Simple logic sugest that if a calorie excess is the cause of obesity, restriction should reverse the gain. However, that this does not occur is proof enough that other factors are the cause of obesity, with overconsumption of fructose and refined carbohydrates likely candidates.
RdB
