Managing weight is about more than energy balance or ‘bad foods’, warn experts
The report – produced by a group of international experts and published in the American Journal of Clinical Nutrition – reviews the components of energy balance, considering the interactions between components of metabolism and the ways in which the body regulates energy imbalances.
Professor John Speakman of the University of Aberdeen, Scotland, explained that the task of the expert committee put together to write the consensus report was to explore the complexities of weight management, “and highlight some of the myths surrounding the energy balance concept."
"Most people are aware of calories and that an imbalance between intake and expenditure of calories leads to weight gain,” said Speakman – who co-authored the consensus statement.
“However, this rather simple concept of energy balance hides within it an extremely complex association between different elements of intake and expenditure."
The consensus statement, put together by the American Society for Nutrition (ASN) and the International Life Sciences Institute (ILSI), is said to have major implications for how we understand the obesity epidemic and how to approach potential solutions.
Complex relationship
The fundamental principle of nutrition and metabolism is that body weight is associated with calories ingested (through food and beverages) and energy expended (through exercise and daily life).
The authors reveal that one key message is that all components of energy balance – including energy intake and expenditure – interact with each other to impact body weight. As a result, they note that a change to any one aspect will correspond to “profound changes in the other side of the equation.”
Speakman and his colleagues said the complexity of this energy balance equation could help to explain why it has been difficult to reverse the current global ‘epidemic’ of obesity.
“That complexity also strongly refutes the popular belief that the obesity epidemic is a result of a few ‘bad foods,’” says Speakman.
Myth busters
The consensus statement also tackled other ‘popular’ myths and beliefs about energy balance and weight management.
Speakman and colleagues said the notion that a reduction of 3500 kcal of energy intake will result in the loss of one pound of body weight is simply false.
“The origin of the ‘3500 kcal per pound’ rule is based on the calculated energy content of body weight change and is often misapplied to predict the weight-change time course after a given intervention,” said the experts. “The impression is given that even a temporary intervention will therefore result in a permanent body weight change.”
“This is a fundamental error because no time period is specified for that intervention.”
The experts added that lifestyle or dietary interventions based on the premise that small changes can amount to a large change over time should be treated with caution.
“It is important not to have unreasonable expectations about the impact of such interventions on body weight,” they said, noting that “because the 3500 kcal per pound rule has often been used to model the effects of such interventions, unrealistic predictions are frequently made about the likely weight-loss benefits of exercise and dietary interventions that make only minor adjustments.”
The panel also dispelled the popular, yet false, belief that the six to eight month ‘plateau’ seen when trying to lose weight is due to a slowed metabolism.
Source: American Journal of Clinical Nutrition
Volume 95, Issue 4, Pages 989-94, doi: 10.3945/ajcn.112.036350
"Energy balance and its components: implications for body weight regulation"
Authors: Hall KD, Heymsfield SB, Kemnitz JW, Klein S, Schoeller DA, Speakman JR.
