Public obesity campaigns fail basic science test
Fundamentally, what most people believe, and what most people have been told about losing weight is wrong— at least to a substantial and material degree.
So, is there little doubt why obesity rates for adults near 30% in America? Most people are trying to address the problem with bad information.
At least that is the conclusion of researchers in Australia, which faces similar rates of obesity increases.
“Public health weight-loss interventions seem to be based on an outdated understanding of the science. Their continued failure to achieve any meaningful, long-term results reflects the need to develop intervention science that is integrated with knowledge from basic science. Instead of asking why people persist in eating too much and exercising too little, the key questions of obesity research should address those factors (environmental, behavioral or otherwise) that lead to dysregulation of the homeostatic mechanism of energy regulation. There is a need for a multidisciplinary approach in the design of future weight-loss interventions in order to improve long-term weight-loss success.”
“Despite the increasing understanding of the mechanisms relating to weight loss and maintenance, there are currently no validated public health interventions that are able to achieve sustained long-term weight loss or to stem the increasing prevalence of obesity in the population. We aimed to examine the models of energy balance underpinning current research about weight-loss intervention from the field of public health, and to determine whether they are consistent with the model provided by basic science. EMBASE was searched for papers published in 2011 on weight-loss interventions. We extracted details of the population, nature of the intervention, and key findings for 27 articles.”
“Most public health interventions identified were based on a simple model of energy balance, and thus attempted to reduce caloric consumption and/or increase physical activity in order to create a negative energy balance. There appeared to be little consideration of homeostatic feedback mechanisms and their effect on weight-loss success. It seems that there has been a lack of translation between recent advances in understanding of the basic science behind weight loss, and the concepts underpinning the increasingly urgent efforts to reduce excess weight in the population.”
“Public health research, recommendations, and interventions relating to the treatment and prevention of overweight and obesity are often based on a simple model of energy balance. This model suggests that change in body weight is equal to energy intake minus energy expenditure, and is often used to show how reductions in caloric intake and/or increases in physical activity will result in successful weight loss that can be maintained over the long term. A common assumption is that energy intake and energy expenditure can be independently modified, through changes in caloric consumption and physical activity, to effect changes in energy balance. For instance, a person could achieve a negative energy balance and thus weight loss, by either reducing their caloric intake or increasing their level of physical activity, or both. This is based on the faulty assumption that each component of energy intake and expenditure can be modified without compensatory changes in other components. However, as is known from much research in the fields of biochemistry and physiology, energy input and expenditure are interdependent and regulated at several levels. This body of research details a far more intricate and complex model of how multiple feedback mechanisms operate to homeostatically regulate energy balance and thus maintain body weight within a relatively narrow range . For instance, when caloric intake is cut the body naturally responds by both stimulating hunger and reducing basal energy expenditure so that less energy is expended. Similarly, a period of increased physical activity can be followed by a period of both increased hunger and increased fatigue, resulting in reduced energy expenditure at other times during the day.
“However, despite this knowledge, public health interventions and dietary guidelines largely neglect this evidence, instead persisting with interventions and recommendations based on an unmodified view of the energy-balance model. As noted by Sorensen, ignoring dependencies that regulate energy intake and expenditure leads to a misunderstanding of the causes of weight gain and thus design of inappropriate interventions that are often unsuccessful in the long term. Using the simple energy-balance model leads researchers to ask the basic question, why do people eat too much, exercise too little and thus gain weight? However, a more nuanced understanding of energy regulation would lead to posing the question, what personal, genetic, environmental, and other factors cause dysregulation of energy balance?
“A number of environmental factors that are potentially problematic for control of body weight, and therefore have implications for intervention design, have also been identified. For example, the hedonistic qualities or hyperpalatability of high-sugar or high-fat products have been suggested to encourage reward driven eating and may over-ride biological controls. The unique metabolic and hormonal effects of chronic and high consumption of carbohydrates, particularly refined carbohydrates, fructose, and sugar-sweetened beverages, have been linked with low satiation, poor appetite control, and a lack of compensation for calories consumed over the short and long term. These factors, which have an increasing role in diet over recent decades, may contribute to excess weight gain and interrupt weight loss and weight maintenance. The role of dietary quality in body-weight control is emphasized by Mozaffarian and colleagues who state that, ‘specific dietary and lifestyle factors are independently associated with long-term weight gain…’ and ‘Individual and population-based strategies to help people consume fewer calories may be most effective when particular foods or beverages are targeted for decreased (or increased) consumption’ . In addition, Bray illustrated differences in weight loss and gain with differences in the macronutrient composition of the diet.
“Although we were unable to identify any public health interventions using more biologically plausible models of energy regulation, more recently there is evidence to suggest a shift towards more complex models of energy balance underpinning interventions in the field of public health. For example, a recent series published in the New England Journal of Medicine examined the role of sugar-sweetened beverages on weight change. It seems the authors investigated these interventions because of their belief that sugars consumed in liquid form may bypass the homeostatic regulation of satiety and reduce the insulin response. The biological model underpinning these interventions remains underdeveloped, addressing only a small component of dietary carbohydrate restriction. However, it is a positive sign to see some consideration of models that are not based on restriction of caloric intake.
“In general, dietary carbohydrate restriction offers an alternative to the energy-balance principle and has shown good results in comparison to low-fat diets particularly in people with metabolic syndrome. The effects are attributed not only to spontaneous reduction in consumption but also to energy inefficiency, popularly known as ‘metabolic advantage’. Researchers in this field have demonstrated the fallacies in the thermodynamic analysis that is supposed to provide support for the energy-balance model. Perhaps because this concept explicitly challenges the ‘calories in, calories out’ model, we were unable to find any public health interventions based on carbohydrate restriction meeting our search criteria and published in 2011.
“The results of this review show the discord between the significant body of research describing the metabolic and physiologic underpinnings of weight gain and loss, and the most recent population-based interventions designed to address the obesity epidemic. We found little evidence of multidisciplinary collaborations and much evidence of a lack of translation between advances in understanding of the basic science and the basis of these interventions.
“As noted by Bray, ‘obesity is a chronic, relapsing, neurochemical disease’. This concept, based on a biological understanding of homeostatic mechanisms, should have led to a change in the framing of key questions of obesity research to address those factors (environmental, behavioral or otherwise) that lead to dysregulation of the homeostatic mechanism of energy regulation. Currently, most research seems to address the question of what factors lead people to eat too much and exercise too little. There is an evident need for a multidisciplinary approach in the design of future weight-loss interventions in order to frame the research questions appropriately. Developing and testing interventions that are based on biologically plausible mechanisms is an important step forward in developing effective interventions to combat obesity and its associated metabolic diseases.”